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Do planning and design policies and procedures matter in microclimate management and urban heat mitigation?

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Title:
Do planning and design policies and procedures matter in microclimate management and urban heat mitigation?
Creator:
Heris, Mehdi Pourpeikari
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
Publication Date:
Language:
English

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Degree:
Doctorate ( Doctor of philosophy)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
College of Architecture and Planning, CU Denver
Degree Disciplines:
Design and planning
Committee Chair:
Troy, Austin
Committee Members:
Muller, Brian
Middel, Ariane
Chawla, Louise

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University of Colorado Denver
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Auraria Library
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Full Text
DO PLANNING AND DESIGN POLICIES AND PROCEDURES
MATTER IN MICROCLIMATE MANAGEMENT AND URBAN
HEAT MITIGATION?
By
Mehdi Pourpeikari Heris
B.S., University of Tehran, 2003 M.S., University of Tehran, 2006 MA., University of Sheffield, 2008
A dissertation submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Design and Planning Program
2018


Pourpeikari Heris, Mehdi
Title: Do Planning and Design Policies and Procedures Matter in Microclimate Management And Urban Heat Mitigation?
Dissertation Committee Chair: Austin Troy Dissertation Adviser: Brian Muller
Dissertation Committee:
1) Ariane Middel
2) Louise Chawla
i


ABSTRACT
In this research, I developed a method for analyzing how urban form affects urban microclimate and how planning and design policies shape urban form. I scrutinized the policies, contexts, and implementation procedures of urban redevelopment projects in two cities in the Denver metropolitan area. Both the Belmar (located in Lakewood, Colorado) and 29th Street Mall (located in Boulder, Colorado) projects were conventional indoor malls developed in the 1960s, that declined in the 1990s, and were redeveloped in the early 2000s to create mixed-use walkable urban centers. The zoning approaches (Belmar used Form-based code, 29th Street Mall used Euclidian), design guidelines, and local politics of these two projects were significantly different in ways that resulted in different built environments after redevelopment. My research aim is to explore how these differences can potentially impact urban climate systems with positive or negative influences on climate variables such as wind, ambient temperature and mean radiant temperature. My research answers two research questions: (1) to what extent are different zoning approaches (Euclidian and Form-based) capable of mitigating urban heat? (2) To what extent are planning contexts, including local politics, important in developing a climate responsive project? I found that a series of variables affected the process of planning and design in these sites. The findings show that the choices made in the development management affected the microclimate of both sites. The built form of Belmar is more effective in heat mitigation and creating a more comfortable temperature. Based on the results of both my microclimate simulations and the policy analysis, I identified five main themes in the development management of both sites that control microclimate outcomes and show why Belmar ultimately was a better project. These themes, which are also relevant for other environmental objectives, are: (1) urban vision, (2) land use and building form controls, (3) design guidelines, (4) public financing, and (5) condemnation/ownership factors. These five policy themes I have identified explain how a combination of context and choice variations affect the quality of built environments. Although many regulations did not intentionally address microclimate issues, elements that were considered for improving walkability contributed to heat mitigation as well. The simulation of policy and form variations showed that the built environment of Belmar has been more successful in mitigating urban heat. Conflicts and a complex planning history in Boulder led to a very slow and ineffective review process that created a less climate responsive built environment.
n


The findings of this dissertation show that the design strategies for improvement of urban microclimate are common strategies with creating a walkable city. In fact, the strategies that FBCs are offering for a good urban design, such as building frontage and landscaping standards, hand in hand with microclimate management. That being said, heat mitigation deserves to be one of the main principles of design and planning strategies. The more important question is how cities can manage development processes to achieve successful projects that address environmental and social values. Hoch (1996) argues that the pragmatic approach to defining the best planning choice can benefit from evaluation of successful projects or best practices to find the important factors. These lessons might be generalizable for other similar situations. The analysis of development management in relation to heat mitigation fits in this category. The themes I introduce in this paper show how planners can improve development management in relation to intended outcomes.
Connecting findings to theory and the literature, conflict in a major project like Belmar or 29th Street Mall is inevitable. Conflict arises in agreeing on visions and goals by developers, cities, citizens, and owners. As Campbell (1996) demonstrated, reaching sustainability goals requires managing different types of conflicts such as property, resources, and development. He raised the question of “whether planners are likely to be leaders or followers in resolving economic-environmental conflicts.” He encourages planners to play a more active role in managing the conflicts rather than mediating the controversy as an outsider. The findings here shed light onto how planners can approach these conflicts and what solutions or tools may be utilized to achieve the goals. What I found in these two projects was that in Belmar the city effectively managed the conflicts regarding financing of the project, ownership obstacles, and laying out the vision through new regulations. Whereas in Boulder, the conflict was not managed effectively and resulted in a long and controversial procedure that failed in addressing climate-related issues.
A big corporate mall developer may not have common values with planning staff in setting goals for environmental or social values. In such situations, I suggest using the five tools identified here to effectively reach the goals of good urban design (presented in the following Figure). Local politics, public participation, and local economics affect the development management procedures and ultimately have a strong control on project outcomes. The findings show that planners need to create an effective process but they also need to create strong visions, and improve regulatory tools such as zoning and design guidelines before starting a major project.
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/------------------N
Urban Vision
\__________________)
Five factors in the development management process that matter for microclimate
management
IV


ACKNOWLEDGEMENTS
I am very thankful for Brian Muller’s role as my adviser for these years of my PhD. He provided significant help as a mentor and as a friend. I also appreciate the profound help and support of Austin Troy. He provided intellectual support and funding that made this path possible. Ariane Middel helped me with providing technical support on microclimate modeling. Louise Chawla, my other committee member, provided detailed help in developing my manuscript.
Besides that, I am deeply grateful for the support that the College of Architecture and Planning at UC Denver and the Program in Environmental Design at CU Boulder provided including scholarships, funding, and a warm home in which to thrive. I would like to especially acknowledge the invaluable and kind helps and supports that Alana Wilson offered. The friendship and mentorship of Shawhin Roudbari irreplaceable. I am also thankful for the helps and supports of MMB in a significant part of my higher education life. Lastly, I would like to offer my deepest gratitude to my family who tolerated the hardships I created for them by studying and living abroad. They inspired and encouraged me with giving me unconditional love on this journey.
v


TABLE OF CONTENTS
I. CHAPTER 1: INTRODUCTION...................................................... 1
II. CHAPTER 2 LITERATURE REVIEW................................................6
Climate Change and Urban Microclimate...........................................6
Climate change Issues........................................................7
Heat waves (as a disaster)..................................................14
Adaptation and mitigation policies..........................................20
Vulnerability:.................................................................20
Urban Heat Islands..........................................................29
The earth’s energy balance at urban scale...................................38
Methods of measuring urban heat island......................................41
Modeling and simulation of the urban microclimate...........................48
Scales of Climate Study.....................................................48
Formulation of Urban Energy Balance.........................................50
Urban energy balance components and urban geometry (form):..................52
Urban heat island mitigation................................................62
Urban heat island mitigation in policy documents in Denver..................64
Conclusion of microclimate section..........................................66
A general literature review of planning and design codes and standards in urban development........................................................................69
Design theories.............................................................69
Urban Renewal Policies......................................................76
Downtown development policies...............................................78
vi


Codes and standards
82
Subdivision regulations........................................................86
Zoning.........................................................................88
Political economy of zoning...................................................101
Zoning: summary and criticism.................................................103
Design Guidelines.............................................................105
Planning procedures...........................................................108
Urban Heat Island Mitigation in Policy Documents..............................108
Conclusion of planning and design policy section:.............................122
III. CHAPTER 3: METHODS...................................................125
Research aim, objectives, and questions..........................................125
Research aim..................................................................125
Research objectives...........................................................125
Research questions............................................................126
Research Design..................................................................127
Case studies.....................................................................128
Belmar........................................................................128
29th Street Mall (Boulder, CO)................................................130
Component 1: Microclimate Simulation.............................................133
Data collection for the experimental phase:...................................133
Site models:..................................................................137
Weather data:.................................................................138
Soil Data:....................................................................141
Validation of simulated results:..............................................141
Urban microclimate simulations................................................143
vii


Policy Scenarios......................................................143
Component 2: Policy Evaluation..........................................147
Theory:...............................................................149
Data collection for the case study research:..........................149
Data analysis for policy evaluation...................................151
IV. CHAPTER FOUR: RESULTS...............................................154
Component one: Microclimate Simulation..................................154
Simulation Results....................................................155
Scenario results......................................................160
Component two: Policy Analysis..........................................168
The story of two sites................................................168
Land use and building form controls:..................................171
Land economy:.........................................................175
Planning contexts:....................................................178
Planning vision:......................................................179
V. CHAPTER FIVE: CONCLUSION............................................183
Final Take-Aways........................................................187
REFERENCES................................................................190
APPENDIX A: INTERVIEW QUESTIONS...........................................201
APPENDIX B: ANALYSIS OF REGIONS AND SCENARIOS.............................203
viii


LIST OF TABLES
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Table
Table
1 Emissivity of Some Materials at 300 K (Cengel & Turner, 2004).................. 35
2 Summary of Some Key Coefficient for Understanding Heat Transfer................37
3 Common Urban Heat Island Observations and Hypotheses (Arnfield, 2003, P:23)....43
4 Thermal Bands of ASTER Satellite Images (Votano et al., 2004)..................47
5 Emissivity of Some Materials (Infrared Thermography Website, Retrieved December
2014 & Erell et al., 2011)........................................................53
6: Thermal Properties of Typical Objects and Materials in Urban Areas (Erell et al., 2011)
......................................................................................60
7 Average annual anthropogenic heat flux (Erell et al., 2011)..........................61
8: Proposed mitigation strategies, maximum potential temperature reduction, and possible
energy savings (Memon et al., 2008)................................................... 64
9: Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of
Denver, 2014)..........................................................................66
10 Urban form elements and microclimate modeling................................67
11: Numbers and Categories of Denver Zoning Districts from 1023 to 1994 (Elliot, 2008:
P.12)..................................................................................92
12: Proposed mitigation strategies, maximum potential temperature reduction, and possible
energy savings.........................................................................110
13: Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of
Denver, 2014)..........................................................................112
14: Urban Heat Mitigation Policies Proposed in the Downtown Development Project (City of Phoenix, 2008).................................................................... 121
15 Case studies.......................................................................132
16 Technical specifications of Lab Jack TLH...........................................134
17 The initial values of the models...................................................141
18 Interview codes and themes.........................................................152
19 Summary of simulation results ( ^ = effective in heat mitigation).................167
IX


LIST OF FIGURES
Figure 1: Atmospheric CO2 at Mauna Loa Observatory (NOAA, Retrieved in November 2014). 7
Figure 2 Observed Change in Surface Temperature 1901-2012 (IPCC, 2013)....................8
Figure 3: Multiple Complementary Indicators of a Changing Global Climate (IPCC WGI, 2013).
..................................................................................10
Figure 4: The effect of changes in temperature distribution on extremes. Different changes in temperature distributions between present and future climate and their effects on extreme values of the distributions: (a) effects of a simple shift of the entire distribution toward a warmer climate; (b) effects of an increase in temperature variability with no shift in the mean (IPCC, 2012). (c) Effects of an altered shape of the distribution, in this example a
change in asymmetry toward the hotter part of the distribution....................12
Figure 5: US Billion-dollar Weather and Climate Disaster time series from 1980-2011 indicates the number of annual events exceeding $1 billion in direct damages, at the time of the event
and also adjusted to 2011 dollars using the Consumer Price Index (CPI)............13
Figure 6: Russia 2010 and US 2012 Heat Wave: temperature anomalies measured by satellites
(NASA Earth Observatory, 2012)....................................................15
Figure 7: Distribution of European Summer Temperatures since 1500 (Barriopedro et al. 2011)
...............................................................................16
Figure 8: Critical Points in Heat-Related Mortality Causalities (Kovats & Hajat, 2008). 18
Figure 9: New Yorkers Crossing Brooklyn Bridge during the 2003 Power Outage (Stone, 2012)
.................................................................................19
Figure 10: Annual Electric Grid Failures in the United States (Stone, 2012).............19
Figure 11: The Relationships between Vulnerability, Exposure, and Climate Events in the
Evaluation of Anthropogenic Risk Management (IPCC, 2014).........................21
Figure 12: Radiative forcing of climate between 1750 and 2011 (IPCC, 2013 WGI)..........24
Figure 13: Total U.S. Greenhouse Gas Emissions, 1990-2012 (EPA, 2014)...................25
Figure 14: Total U.S. Greenhouse Gas Emissions by Economic Sector in 2012...............26
Figure 15 Conceptual Relationships between Climate Change Adaptation and Mitigation Plans
and Public Health ressource McMichael, et al.(2006)..............................28
Figure 16: Daytime and Nighttime Temperature Anomalies Resulting in Urban Heat Island (EPA, 2008)................................................................................. 30
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Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
17: Heat Transfer through Conduction (£engel & Turner, 2004)....................... 34
18 Convection Heat Transfer: hot air has low density and rises; cool air has high density
and sinks (Cengel & Turner, 2004).................................................. 34
19 The Absorption of Radiation Incident on an Opaque Surface of Absorptivity (Cengel &
Turner , 2004)................................................................ 36
20: Incident Radiation May Be Reflected, Transmitted, or Absorbed (Pan, 2011)......37
21 The Global Annual Meant Earht's Energy Budget for the Mar 2000 to May 2004 (Wm"
2) (Trenberth et al., 2009)....................................................40
22 Contributions of Urban Landscape in Imbalance of the Earth's Energy Budget (EPA,
2008)..........................................................................41
23 Observation of Luke Howard: the annual temperature curves (1797 to 1816) for the city
(solid) and rural area (dashed) (Mills, 2008)......................................42
24 Portable Weather Stations That Log Temperature, Relative Humidity, Radiation,
Precipitation (Rain), Wind Speed/Direction.....................................45
25 Atmospheric Layers above Urban Areas (Erell, 2011).........................49
26: Conceptual Framework of Urban Energy Balance for Microclimate Modeling (Erell et al., 2011).....................................................................51
27 Shortwave (Direct and Diffused) and Longwave Radiation (Erell et al., 2011)....52
28 The Role of Street Ratio in Reflection of Solar Radiation (Erell et al., 2011).54
29 Sky View Factor Measurement Method (Erell et al., 2011)........................55
30 3D Sky View Factor Measurement Method (Erell et al., 2011).....................55
31 Long-wave Radiation Emitted from Surfaces..................................57
32 A Typology of Urban Design Projects (Lang, 2005)............................... 71
33 Yazd (Left) and Gonaabaad (Right) Climate Responding Organic Design in Iranian
Cities (Tavassoli, 2002 P:19)..................................................75
34 Shopping Mall in Chandler, Arizona, a product of neglecting the side effects of rules
(Talen, 2013; P: 2)............................................................85
35, Transect Zones: Rural to Urban Characters (FBCI, 2014).........................98
36 Proposed Building Massing (Phoenix, 2008)................................. 119
37 Building Frontage Regulations from the Design Guidelines of Downtown Belmar,
Lakewood, CO...................................................................122
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Figure
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Figure
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Figure
Figure
Figure
Figure
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Figure
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Figure
Figure
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Figure
Figure
Figure
38 Dissertation conceptual model and components................................128
39: Aerial Photo of Belmar before (left image, 1999) and after (right image 2014) (Captured from Google)...............................................................130
40 Belmar Site Plan of the redevelopment project...............................130
41 Aerial Photo of 29th Street Mall before (left image, 2002) and after (right image 2014)
(Captured from Google)............................................................131
42 Temperature/Light/Humidity (TLH) Data Logger Produced by LabJack.............135
43: Tagged data loggers ready to be located in the field.........................135
44 Location of data loggers in the site maps (red circles).......................136
45: Loction of data loggers.......................................................137
46 Temperature variations collected by a data logger in Belmar (sample period: June 20th
- July 5th).......................................................................139
47 Light variations collected by a data logger in Belmar (sample period: June 20th - July
5 th).............................................................................140
48 Relative humidity variations collected by a data logger in Belmar (sample period: June
20th - July 5th)..................................................................140
49 Site layouts for the existing condition scenario.............................144
50 Site layouts for the building scenario.......................................145
51 Site layouts for the street scenario.........................................145
52 Site layouts for the vegetation scenario.....................................146
53 Site layouts for the vegetation scenario.....................................147
54 Content analysis of interviews...............................................153
55 Distribution of Simulated Air Temperature at 2 meters above ground at 3pm on June
29th 2015 for Belmar (left) and 29th Street Mall (right).........................156
56 Distribution of Wind Speed (meter/second) at 2 meters above ground at 3pm on June
29th 2015 for Belmar (left) and 29th Street Mall (right)..........................156
57 Measurement regions and mean radiant temperature in Belmar (existing condition) 157
58 Measurement regions and mean radiant temperature in 29th Street Mall in Boulder
(existing condition)..............................................................157
59 Simulated versus observed air temperature in the data logger number 3 location of
Belmar............................................................................158
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Figure
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Figure
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Figure
Figure
Figure
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60 Simulated versus observed air temperature in the data logger number 4 location of
Belmar........................................................................158
61 Simulated versus observed air temperature in the data logger number 2 location of
Boulder........................................................................159
62 Simulated versus observed air temperature in the data logger number 3 location of
Boulder........................................................................159
63 Simulated air temperature of scenarios of Belmar in Lakewood...............161
64 Simulated air temperature of scenarios in 29th Street Mall in Boulder......162
65 Comparison of microclimate variables across all scenarios where H values are hours of
the day of simulation..........................................................163
66 Comparison of Mean Radiant Temperature (MRT) for the building height scenario
(shorter building height) and existing condition in region 7 of Belmar........165
67 Comparison of wind speed and air temperature for the street pattern scenario (linear
layout) and existing condition (grid layout) in region 9 of Belmar............166
68 Average housing value in Boulder and Lakewood (Zillow website, 2017).......169
69 Boulder valley design guideline............................................172
70 Design guideline of 29th Street Mall in Boulder...........................173
71 Design guideline of Belmar.................................................174
72 The site plan that Civitas proposed in 2002................................182
73 Dissertation conceptual model and components...............................183
74 Five factors in the development management process that matter for microclimate
management.....................................................................189
xm


I. CHAPTER 1: INTRODUCTION
This dissertation aims to explore how urban development and urban form policies and their implementation processes can mitigate or exacerbate heat in cities. I compare two urban redevelopment projects in the Denver metropolitan area: (a) Belmar project in Lakewood, CO and (b) 29th Street Mall project in Boulder, CO. To understand how form shapes urban microclimate, I simulated morphological factors including buildings, trees, and impervious/permeable surfaces, to generate microclimate variables (outcomes) such as air temperature, wind speed/direction, and mean radiant temperature. To explain how planning and design policies and procedures shaped urban form, and thereby the microclimate outcomes, I scrutinized the main planning and design policies of each site and their policy making and implementation procedures using qualitative methods.
Anthropogenic changes to climate have already raised the average temperature of our planet by about 0.8°C compared to its pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC) (2013) has projected that the average temperature of our planet will increase by 4-6°C by the end of this century. In addition, studies show that urban areas are warmer than their surroundings by 1-4°C (depending on variations of general climatic and spatial situations) (EPA,
2008) . Analyzing observed and simulated data shows that urban areas will be affected more intensely and frequently by extreme heat events, and in general by an increasingly warming climate (IPCC, 2013).
The mortality and morbidity of people due to urban heat when intensified by heat waves are remarkable. The past two decades marked a record in the number of extreme hot days (heat waves) around the world (Coumou & Rahmstorf, 2012). Examples of such events include the European heat wave of 2003 (Stott et al. 2004), the Greek heat wave of 2007 (Founda and Giannaopoulos
2009) , the Australian heat wave of 2009 (Karoly 2009), the Russian heat wave of 2010 (Barriopedro et al. 2011), the Texas heat wave of 2011 (NOAA, 2011; Rupp et al. 2012), and the U.S. heatwave of 2012 (NOAA, 2012; 2012b). The five hottest summers in Europe since 1500 all occurred after 2002, with 2003 and 2010 being exceptional outliers (Barriopedro et al. 2011). The number of mortalities attributed to the heat waves are shocking. According to Stone (2012) 70,000 people died in the heat wave of 2013 in Europe. Smenza et al (1996) identified 700 deaths related
1


to the heat wave of 1995 in Chicago. The urban heat issue is also an environmental justice issue because it does not affect all social groups evenly. Harlan et al (2006) explored heat-related health inequalities and found that lower income and minority groups are more likely to be exposed to higher temperatures. They argued that these groups also are more vulnerable as they have less capacity to cope with higher temperatures on summer days and nights.
Higher temperatures can also affect energy and water usage in urban areas. Studies show that electricity use can increase by about 10% for every 1°C increase in temperature (in the range of 35°C) (Akabri et al, 2005 and EPA, 2008). Studying the consequences of heat waves also shows that electricity grids might not have the capacity to meet high demands for power in extreme heat waves. This was experienced in the North-East region when the heat wave of 2003 caused significant and extensive power outages (Stone, 2012). Power outage in an extreme heat wave can then expose vulnerable populations to significant risks. Water use can also increase with higher temperatures. Aggarwal (2012) found that water consumption in single family residential housing units in Phoenix, Arizona increased by about 3% for every 1°C increase in outdoor temperature (in the rage of 37°C).
The literature suggests that urban built environments can potentially increase or decrease ambient and mean radiant temperatures. Form elements such as building shapes and orientation, surface and roof color, impervious surfaces, trees and vegetation quantity and distribution, and street form and directions are important for heat mitigation. As it is thoroughly discussed in the literature review chapter, urban microclimate is related to built environment configurations and elements. This means that different urban morphologies (as a general term for urban form and configuration) could produce different microclimates (1-3°C difference among neighborhoods of one city). Considering all consequences of urban heat in relation to public health, energy and water consumption, and social life of public spaces, it is an essential subject in the design of cities to understand how policy variations and form variables change microclimates and potentially mitigate urban heat. Adopting a design approach to mitigate urban heat will make cities more resilient in the changing climate.
Considering that primary design strategies for heat mitigation at the site scale concern building envelopes, trees, and landscaping qualities, this suggests that several policies and planning tools can be targeted to influence urban microclimates. For example, zoning regulates
2


building envelopes, location of building footprint within parcels, open spaces, and use. Subdivision codes regulate the ratio of building-height to street width, street patterns and orientation, and so on. Fundamentally, codes and standards are “the hidden language of place making”, and various standards, such as building fire codes and design guidelines, have influenced building forms, street forms, and land subdivisions (Ben-Joseph and Kiefer 2005). Not only are codes and regulations important, but the cross-effect of regulations also matters, as Talen (2013) highlights. For example, the combination of a poorly designed parking requirement regulation and poor landscaping standards may generate vast parking lots that exacerbate urban heat. Shaping and regulating urban form and landscaping with more details requires fine-scale design policies that have received attention through form-based codes. In this dissertation, I will discuss how policies need to be designed specifically to address issues such as microclimate.
Research on microclimate and urban morphology is particularly important at a time in which the urban form of U.S. cities is changing quickly (Estiri et al., 2014) and the urban core of many major metropolitan areas is becoming denser (Heris 2017). Urban morphological change of this kind tends to last a long time, and the current demand for densification offers an opportunity to consider how new morphologies can be optimized for climate-related values.
Although several U.S. cities have established heat-related policies (e.g. Tucson, AZ & Chicago, IL), few have embedded heat regulations in tools such as zoning. My dissertation illuminates a gap in both theory and the practice of planning and design in relation to prescribing fine-scale policies and design strategies to address heat mitigation effectively. To translate heat mitigation strategies to planning practices, we need to build a scientific knowledge of heat mitigation solutions. In addition, planning theory needs to readdress the importance of fine-scale regulations, such as form-based zoning, in redevelopment projects. Furthermore, planning theory needs to connect environmental values such as microclimate to social and environmental justice discourses. Without understanding how environmental values are consistent or inconsistent with justice values, addressing conflicts in the planning procedure cannot be comprehensive. Planners need to have solid knowledge of climate-related processes in parallel with justice issues to be able to mend the planning process for better outcomes. This dissertation connects the science of microclimate to urban planning and design policies and their implementation procedures. The findings of this research help planners to systematically embed form and landscaping regulations
3


in common tools such as zoning and design guidelines to address heat mitigation. Furthermore, I shed light on the planning process versus outcomes to show how different choices in the implementation phase affect urban microclimate.
Research Design:
To address these gaps, this dissertation has two main and one subsidiary research questions:
1. To what extent do planning policies improve or degrade urban microclimate?
• Comparing form-based codes and conventional zoning as two different approaches, which one can provide a better foundation for climate-responding design and adopting heat mitigation strategies?
2. In what ways do planning procedures (discretionary processes) influence the implementation (built environment outcomes) of policies with respect to microclimate outcomes of redevelopment projects?
To answer the research questions, I compare two urban redevelopment projects in the Denver metropolitan area: (a) Belmar proj ect in Lakewood, CO and (b) 29th Street Mall proj ect in Boulder, CO. Both the Belmar (located in Lakewood, Colorado) and 29th Street Mall (located in Boulder, Colorado) projects were conventional indoor malls developed in the 1960s, that declined in the 1990s, and were redeveloped in the early 2000s to create mixed-use walkable urban centers. Belmar uses a form-based code and PUD whereas 29th Street Mall of Boulder uses a conventional zoning. Both sites share a similar history and importance in their contexts and provide a unique opportunity to compare their policies and implementation procedures. I examine the different urban morphologies of these recently redeveloped urban centers in relation to their microclimates. There are several studies in which simulations of microclimate systems have been developed at a neighborhood scale for residential land uses. However, simulation-based research on microclimate systems and temperature effects has not been undertaken in urban centers and mixed-use developments such as downtown areas in relation to design policies. I attempt to answer the fundamental question of whether the current planning and design policy frameworks contribute to heat mitigation or not. Answering this question goes beyond the microclimate science because the overall impact of policies on other systems such as walkability needs to be addressed in the context of planning. Therefore, my dissertation bridges the science of microclimate to urban planning and
4


design policies. My main hypothesis is that some certain morphologies can mitigate urban heat through regulating radiation and wind circulation. Also, the existing policy frameworks matter in shaping urban form with such influences.
This dissertation looks how morphology affects climate and how policy affects morphology. To explore these relationships, the dissertation is divided into two main components. The first component concerns urban microclimate simulations using an empirical research design. I used ENVI-met to simulate urban microclimate variables based on the built form configurations of the two case study sites. This component explores the relationships between urban microclimate and urban form elements such as building height, tree density, permeable and impervious surfaces, etc. The simulation results are validated by temperature data loggers. The second component of the dissertation is built on the outcomes of the first one and uses a case study research design. Knowing how form elements affect microclimate, this component examines how microclimate outcomes at the sites are affected by planning choices and contexts. I examine the effects of regulatory systems including different types of zoning (form-based vs conventional), planned unit developments (PUDs), and design guidelines, as well as context variables such as ownership and vision conflicts.
The dissertation includes five chapters. After this introduction, in the second chapter I review the literature of climate change, urban heat islands, urban microclimate, and design and planning policies. The third chapter explains the research design, case studies, and analysis methods. Chapter four articulates the results and findings of the research including the outcomes of microclimate simulations and their validation results, policy analysis and interviews. Chapter five is the conclusion.
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II. CHAPTER 2 LITERATURE REVIEW
Climate Change and Urban Microclimate
All scientific studies about climate change and its drivers show that the earth will be in a great danger if humanity continues to influence Earth’s climate systems with the current pace. One of the most reliable resources in climate change studies are the reports published by IPCC1 (Intergovernmental Panel on Climate Change) which has integrated most relevant studies. These reports have informed scientific and political communities and promoted climate change research.
In recent decades, changes in climate have impacted natural and human systems. The evidence of climate change impact is strongest and most comprehensive and visible for natural systems. IPCC (2013) in the fifth assessment report (AR5) has warned that climate change is occurring and affecting the climate systems and weather patterns with a quicker pace than was expected. IPCC has projected that the average temperature of our planet will increase by 4 to 6 degrees Celsius by the end of this century. Several studies show that chances of extreme weather occurrences, including heat waves, will be higher. Evidence shows that ecosystems and human systems are vulnerable to climate-related extremes, such as heat waves, droughts, floods, and wildfires. The impact of such climate-related extremes includes alteration of ecosystems, damage to infrastructure and settlements, consequences for mental health and human well-being, morbidity, and mortality.
In this paper, first, I review the literature of climate change, its related evidence, trends, and consequences. Following this section, I review the literature of extreme weather events and related adaptation and mitigation policies. The following section discusses urban heat waves and their
1 IPCC is a scientific intergovernmental body sponsored by the United Nations, which has been set up by the request of member governments. IPCC was first established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP), and later endorsed by the United Nations General Assembly through Resolution 43/53. IPCC was established to gather together the world leading climate change scientist to provide unbiased and valid research on the evidence and trends of climate change and its drivers. They publish periodic assessment reports reviewing the progress made on climate change science including adaptation and mitigation policies.
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impacts on public health. The final section is dedicated to the urban heat island effect, its drivers, science, and mitigation policies.
Climate change Issues
Observed changes and trends
It is proven by many studies that the main driver of global warming and climate change is an increase in the concentration of CO2 in the atmosphere, causing greenhouse effect. Measuring CO2 changes in the atmosphere was started by Charles D. Keeling who made systematic measurements of atmospheric CO2 emissions in 1958 at the Mauna Loa Observatory, Hawaii which is a remote place and therefore, is uninfluenced by regular pollutions (Keeling et al. 1976). These observations have been continuing to today. Results (for the amount of CO2 in atmosphere) show (Figure 1) an increase from 316 ppm (parts per million) in March 1958 to 395,93 ppm in November 2014 (NO A A, 2014).
Atmospheric C02 at Mauna Loa Observatory
Figure 1: Atmospheric CO2 at Mauna Loa Observatory (NOAA, Retrieved in November 2014)
Recent studies estimate that the global average temperature is now 0.8°C above preindustrial levels. This increase in temperature is the globally averaged and combined land and ocean
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temperature data as calculated by a linear trend and shows a warming of 0.85 (0.65° to 1.06°C) over the period 1880-2012 (IPCC, 2013). Figure 2 shows the observed change in surface temperature since 1901. Independent studies using different resources found similar temperature increase on the land and in oceans. There are natural factors that impact the global average temperature variations such as solar radiation fluctuations, volcanic events, and El Nino/Southern Oscillation. In the mentioned studies, these natural variations have been considered. IPCC (2013) in the last assessment report (AR5) argue that without the anthropogenic climate change, natural factors could even decrease the global average temperature.
Observed change in surface temperature 1901-2012
-0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 1.25 15 1.75 25
CC)
Figure 2 Observed Change in Surface Temperature 1901-2012 (IPCC, 2013)
Increases in the concentration of CO2 in the atmosphere have resulted in similar trends in oceans. The dissolved CO2 in oceans has been increasing as well and has resulted in a significant change in the pH of water. This will make the water more acidic, which can impact on the ocean species specially corals.
IPCC in AR4 (2012) and AR5 (2013) argues that it is very likely that the observed increase in global temperature is due to increase in anthropogenic greenhouse gas concentration in the atmosphere (IPCC, 2013; IPCC, 2012). Several studies (i.e. Wigley & Santer, 2012; Santer et al., 1995; Stott et al., 2000) have explored natural factors that can influence temperature such as solar
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variations, volcanic aerosol effects, and El Nino. The results show that over the last 50 years the summary of these variations would likely have contributed to cooling, not warming of global temperature. The increase of global temperature has resulted in significant loss of ice from Greenland and Antarctica. The IPCC AR5 reported 0.41 ±0.4 mm per year as the rate of sea-level rise from the ice sheets for the period 1993-2003, while a more recent estimate by Church et al. in 2011 gives 1.3 ±0.4 mm per year for the period 2004-08. Measurements show that the pace of ice mass loss has risen over the last two decades as estimated from a combination of satellite gravity measurements, satellite sensors, and mass balance methods (Velicogna 2009; Rignot et al. 2011).
Figure 3 compares temperature anomalies of land surface, sea surface, and atmosphere. There is an evident trend in all temperature types presenting a significant increase. This trend also correlates with sea ice extent loss and sea level rise (IPCC, 2013). The scientific research and reports collected and presented by IPCC shows the depth climate change and its influence on natural and human systems. All evidence shows that the Earth’s climate is changing due to anthropogenic activities. Figure 3 summarizes the changes of some important weather parameters. In this figure, it is evident that there is a similar trend in these variables.
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Figure 3: Multiple Complementary Indicators of a Changing Global Climate (IPCC WGI, 2013).
Future global, regional, and local climate
Projection models suggest that changes of climate systems significantly impact extreme weather events (Karl et al., 2008). The increase of average global temperature by 4-6°C can trigger many events including heavy precipitation, long droughts, heat waves or extreme hot days, and storms (IPCC, 2013). For instance, in the recent decades most regions in North America have been experiencing more unusually hot days and nights, fewer uncommonly cold days and nights, and fewer frost days. Heavy precipitation has happened with more frequency and intensity (Handmer et al., 2012). According to Karl et al., droughts are becoming more severe in some regions. The
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Mats balance (101,GT) Extentanomaly (1(7W) Specific humlcJfty Ocean heat content Temperature
a nomaly (gfltg) anomaly (Iff22 J) anomaly fC)


intensity and frequency of Atlantic hurricanes have increased significantly in recent decades; however, there is not an observed significant trend in North America.
Large fraction of anthropogenic climate change resulting from C02 emissions is irreversible on a multi-century to millennial time scale, except in the case of a large net removal of C02 from the atmosphere over a sustained period (Cai et al., 2013). Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic C02 emissions (IPCC, 2013). Due to the long time scales of heat transfer from the ocean surface to depth, ocean warming will continue for centuries. Depending on the scenario, about 15 to 40% of emitted C02 will remain in the atmosphere longer than 1,000 years.
One of the most visible signs of global warming with direct influence on people’s lives is the rise of temperature. If the current trend in producing GHGs continues, models project that the average annual temperature of our planet will increase by at least 4°C at the end of this century (Schellnhuber, Hare, & Serdeczny, 2012). Even considering the current commitments and pledges by governments would occur, there would about 20 percent likelihood of exceeding 4°C by 2100 and a 10 percent chance of exceeding 4°C by the 2070s (IPCC, 2013). Schellnhuber et al. (2012) argue that exceeding 6°C increase in average temperature could expose human and other species to serious risks and probably to an end point.
Anthropogenic climate change results in increases in the frequency, severity, geographic extent, and duration of extreme weather events. Figure 4 shows how changes in climate systems can increase the frequency and intensity of extreme weather events. IPCC (2012) shows that there is a significant decreasing trend in the number of extreme cold days and nights while there is an increasing trend in the number of extreme warm days and nights at the global scale. There is sufficient historical data on land to support this argument confidently. Also, there have been statistically significant trends in the number of heat waves, floods, heavy precipitation events in regions and sub-regions. A warmer climate would increase the risk of floods (Hirabayashi et al., 2013). The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas has increased. Guhathakurta et al (2011) found that extreme rainfall and flood risk are increasing significantly in India except some parts of central India. IPCC (2013) also reported that besides some irregular patterns, the number of extreme precipitation events has been increasing globally.
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Increase in Probability of Extremes in a Warmer Climate
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Figure 4: The effect of changes in temperature distribution on extremes. Different changes in temperature distributions between present and future climate and their effects on extreme values of the distributions: (a) effects of a simple shift of the entire distribution toward a wanner climate; (b) effects of an increase in temperature variability with no shift in the mean (IPCC, 2012). (c) Effects of an altered shape of the distribution, in this example a change in asymmetry toward the hotter pari of the
distribution.
The magnitude of disasters is not only related to the extreme weather. It also depends on the vulnerability and resiliency of the communities. For example, economic recessions and wars can increase the vulnerability of settlements. The extent of vulnerability in a society is the outcome of some factors such as population dynamics and economic status as well as adaptation measures such as appropriate building codes, disaster preparedness, and water use efficiency. In the disaster risk management related to extreme weather events, three parameters (Figure 11) should be considered: (1) severity of extreme weather events, (2) level of community exposure, and (3) vulnerability. Anthropogenic climate change can influence all the above parameters; therefore, climate change adaptation and mitigation policies need to address vulnerability, extreme weather events, and exposure.
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Billion Dollar Weather/Climate Disasters
1980- 2011
NOAA/NESDIS/NCDC
80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 00 09 10 11
Years (1980-2011)
Figure 5: US Billion-dollar Weather and Climate Disaster time series from 1980-2011 indicates the number of annual events exceeding $1 billion in direct damages, at the time of the event and also adjusted to 2011 dollars using the Consumer
Price Index (CPI)
Models project considerable wanning in temperature extremes by the end of the 21st century. IPCC (2012) claims that “it is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extreme will occur in the 21st century at the global scale” (P:13). IPCC suggests three scenarios for the amount of GHG emission till the end of the current century. The first scenario (A1B) which projects higher GHG concentration in the atmosphere predicts an increase in heat waves from 1-in-20 year hottest day to l-in-2 year event by the end of 21st century. Taking the third scenario into account (B1), heat waves will increase from 1-in-20 year to l-in-5 year event. According to all three scenarios, it is very likely that the duration, frequency, and intensity of warm periods or heat waves will increase in most regions of the world. There are similar outcomes about other extreme weather events such as tropical cyclones, flood, droughts, heavy precipitation, etc.
To summarize, in spite of clear evidence that human activity is driving climate change and extreme weather events, there are considerable uncertainties in predicting future extreme events
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Damage Amounts in Billions of Dollars


(IPCC, 2013). Science of climate can proj ect the average temperature not the timing and magnitude of the events (Field, 2012). On the other hand, the resiliency and adaptation capacity of the communities are dynamic qualities (Cutter et al., 2008). All these dynamic variables make projecting the vulnerability of a community problematic. The general recommendation of IPCC is enabling communities to be less vulnerable in extreme weathers through both adaptation and mitigation strategies. Figure 5 shows an increasing trend of climate and weather related disaster costs since 1980 in the US.
Heat waves (as a disaster)
In the previous sections, I articulated how both observations and projections suggest that climate change increases the frequency, intensity, and length of extreme heat events. The past decade marked a record in the number of extreme hot days (heat waves) around the world (Coumou & Rahmstorf, 2012). Examples of such events include the European heat wave of 2003 (Stott et al. 2004), the Greek heat wave of 2007 (Founda and Giannaopoulos 2009), the Australian heat wave of 2009 (Karoly, 2009), the Russian heat wave of 2010 (Barriopedro et al. 2011), the Texas heat wave of 2011 (NOAA, 2011; Rupp et al. 2015), and the U.S. heat wave of 2012 (NOAA, 2012; 2012b). Figure 6 shows the surface temperature anomalies in the heat wave of 2010 in Russia and 2012 in the US. These heat events usually resulted in many heat-related mortalities, wild fires, and agriculture crop losses (e.g. Coumou & Rahmstor, 2012).
Heat wave is a relative concept varying in different locations. The temperature that can be assumed high in London could be a usual day in Phoenix. Heat events represent unusual (extreme) temperature for the average local temperature. These events were highly unusual with monthly and seasonal temperatures usually higher than three standard deviations (sigma) than the local average temperature. For that reason, these events are called three-sigma events. Without anthropogenic climate change, such three-sigma events would probably happen only once in several hundreds of years (Hansen et al. 2012). As it is presented in Figure 7 the five hottest summers in Europe since 1500 all occurred after 2002, with 2003 and 2010 being exceptional outliers (Barriopedro et al. 2011).
In July 1995, the record-setting heat wave in Chicago, at least 700 deaths were attributed to excessive heat exposure. Smenza et al (1996) used a very precise method to measure heat related mortalities from July 14 through July 17, 1995. They interviewed 339 relatives, neighbors, or
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friends of those who died. They found interesting information about the condition of people impacted by heat and found that the risk of heat-related death was increased for people with known medical problems who were confined to bed or who were unable to care for themselves. People who lived alone or lived on the top floor of a building were affected more intensely. The study shows that having social contacts such as group activities or friends in the area was protective. In other words, people with weak social support with medical illness were at great risk.
Figure 6: Russia 2010 and US 2012 Heat Wave: temperature anomalies measured bv satellites (NASA Earth Observatory,
2012)
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Temperature (°C)
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1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000
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Figure 7: Distribution of European Summer Temperatures since 1500 (Barriopedro etal. 2011)
The number of people died because of the 2003 heat wave is estimated about 70,000 (Field et al. 2012), with daily excess mortality reaching up to 2,200 in France (Fouillet et al. 2006). This heat wave that set a record of 7°C higher than average temperatures is considered the single most catastrophic weather event in Europe since weather observations have been recorded. Barriopedro et al (2011) claims that the magnitude of this event attracted attention to heat waves as a silent killer. Seven years later, the heat wave in Russia in 2010 caused about 55,000 deaths (Barriopedro et al. 2011). In 2012, the Americans, experienced a sever heat wave and drought period (NOAA 2012, 2012b). In the same year, the United States had several wildfires, marking a new record in terms of impacted areas (7.72 million acres) (NOAA 2012b).
1.
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Body mechanism for dealing with heat
Long exposure to high temperatures can lead to “heat-related illnesses, including heat cramps, heat syncope, heat exhaustion, heat stroke, and death.” Heat exhaustion is the most common issue leading to heat stroke which is a “severe illness clinically defined as core body temperature 40.6°C (105°F), accompanied by hot, dry skin and central nervous system abnormalities, such as delirium, convulsions, or coma.” (Luber & McGeehin, 2008; P:429). The elderly and people with chronic medical conditions (e.g., cardiovascular disease, obesity, neurologic or psychiatric disease) are at high risk.
As Luber & McGeehin (2008) point out, estimation and measurement of heat-related mortality is challenging because illnesses such as heat exhaustion and stroke are not considered as serious problems requiring reporting to national health agencies by hospitals as heat-related crises. Also heat-related health problems cause other conditions (e.g. heart failure in people with chronic heart illnesses). The criteria used to attribute heat-related deaths vary among states and countries. According to Luber and McGeehin (2008) medical examiners attribute heat exposure as a primary or contributing cause of death only if they record a core body temperature of above 40.6°C (105°F). Besides mortality, significant numbers of morbidity have been recorded in heat waves. For example, according to Semenza et al. (1996) over 1000 excess hospitalizations were recorded as heat-related in Chicago 1995.
High temperature increases the pressure in the human body through loading more intense work to heart and other organs. As temperature rises, blood circulation should be faster to deliver water required for perspiration effectively and also to mitigate the excessive core temperature. As long as the lost water is constantly replaced, the body would be able to maintain the core temperature through perspiration. However, the heart would be increasingly under pressure to circulate fluids at an elevated rate. Sweating also will contribute to sodium loss, which increases the stress in other organs. The lack of water will make blood thicker and consequently will raise the risk of clotting which can lead to heart attack or stroke. The lack of sodium will cause muscle cramp and spasm and dysfunction of internal organs. Stone (2009) states that human body can tolerate the exposure to excessive heat for about 48 hours before suffering heat related symptoms.
The duration of warm days is one of the most important variables that can influence high risk populations. However, heat exposure is not the only variable. People who do not have social
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support to act appropriately or people who have chronic illnesses will be victims of heat waves. Figure 8 shows factors that play an important role at each phase (Kovats & Hajat, 2008).
Factors affecti ng exposure
Factors affecting sensitivity to a given heal exposure
FHCtOfS affecting access to treatment
\7 \7
Heat - Heal stress - Heat illness (clinical signs) - Heat death

Figure 8: Critical Points in Heat-Related Mortality Causalities (Kovats & Hajat, 2008)
Heat stress influences people’s behavior. Wyon et al (1996) found that heat stress negatively affects the vigilance of drivers. They compared the behavior of drivers in 21°C and 27°C in responding to signals. Their research showed that at 27°C drivers missed the signals 50% more than the same situation in 21°C. Also, the response time was longer. Stone (2009) notes that the heat intensity could be much higher inside the vehicles. In the 2003 heat wave the temperature inside the cabins of a tram could reach to 48°C (120°F). Many studies (e.g. Grandjean & Grandjean 2007) show that heat stress decreases the efficiency and cognitive capacity of people in doing their daily activities.
Heat wave and stress on urban infrastructure
Heat waves also increase the stress on urban infrastructure. A long heat exposure increases the demand for air conditioning use which consequently increases the demand for electricity. In a normal summer day about one-third of electricity use in domestic buildings is related to air conditioning systems (Lam, 2000). Excessive heat can increase this number significantly. The raised demand of electrical power can result in failure of power generation and transition as well. Power plants could also stop because of excessive load. Stone (2009) notes that in the 2003 heat wave, in some cases, the temperature of some nuclear power plants approached the thresholds that would have required an immediate shutdown.
On August 14, 2003 the United States experienced one of the most massive power outages in American history. A high load to the electrical grid caused failure of distribution system in some
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Mid-western and Northeastern states. According to Stone (2009) 55 million residents of Mid-Western and Northeastern cities experienced an extensive power outage. The blackout in Manhattan, New York was visible and significant because of high population density and high rise buildings. New York subway could not function and streets were blocked by traffic jams. Population had no way to leave Manhattan except walking away. Figure 9 shows New Yorkers that were trying to leave Manhattan in the absence of public transportation. Figure 10 illustrates that the number of electrical grid failures is increasing.
Figure 9: New Yorkers Crossing Brooklyn Bridge during the 2003 Power Outage (Stone, 2012)
150 r-

Figure Annual «*livi ric til grid lailurr.-t in I lit- [.failed Sl;rU*s:
1992-2009. Swim; North American Electric Reliability Corporation (data for 2008 are unavailable).
Figure 10: Annual Electric Grid Failures in the United States (Stone, 2012)
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The lack of power can cause several other problems such as having access to public transportation, water, telecommunication, and other infrastructures dependent on electricity. For example, delivery of water requires pumps to deliver in higher elevations such as skyscrapers. Without power, many buildings and offices will not have access to water. Another unexpected consequence of the 2003 heat wave in Europe was the closure of rail systems and roadways (Stone, 2012). Railways particularly are susceptible in extreme heat waves because the thermal expansion of rails increases the risk of derailing trains. According to Stone (2012) in the 2003 heat wave a freight train derailed near London. Similar to rails, the surface of roads and the structure of bridges may be affected in extreme heat waves. In a very hot day, some airplanes are not able to take off because of thin air at the ground level.
Studies show that warm days can reach to an extreme heat event severity, exacerbated by urban heat island effect. Tan et al (2010) found more extreme heat events in urban areas compared to exurban neighborhoods in Shanghai, China. They found that urban heat island effect can potentially increase the duration of heat periods and consequently increase heat related mortalities.
There are at least three trends that suggest heat waves could cause significant mortalities in the future. The first trend is the general global warming that has been discussed in the previous section. IPCC projects that this increase could be about 4°C by the current mid-century. The second trend is aging population in the major large cities mostly because of increasing life expectancy. The elderly populations are in greater risk compared to others. The third trend is growing urbanization which can potentially exacerbate urban heat island effects. These three effects together increase the risk of mortality and requires targeted adaptation and mitigation strategies.
Adaptation and mitifiation policies
Vulnerability: All studies and evidence show that human communities and natural ecosystems will be exposed to a greater risk (magnitude and frequency) of extreme weather events. One of IPCC’s (2014) working groups (WGII) overlays the climate change facts and projects on human settlements to measure the global risks. This group studies how risk patterns are shifting due to climate change. In their recent report (WGII AR5) the adaptation and mitigation opportunities and requirements are articulated. This report focuses on risk and advances the approaches for improving planning processes in all scales. Figure 11 (IPCC, 2014) shows how anthropogenic climate change increases hazards and consequently increases risk. Socioeconomic
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processes and adaptation/mitigation efforts could also influence risks and vulnerability. This cycle is the core of adaptation and mitigation guidelines. Uneven development and injustice usually increase vulnerability in lower income groups.
CLIMATE
Namral
Variability
Anthropogenic
Clbrtate ChArtye
IMPACTS
SOCIOECONOMIC
PROCESSES
Socioeconomk
Pathway*
AdaptalKHi flnti Mitigation Actions
Governance
EMISSIONS and Lard-use Change
Figure 11: The Relationships between Vulnerability, Exposure, and Climate Events in the Evaluation of Anthropogenic-
Risk Management (IPCC, 2014)
Vulnerability is a function of the extent to which a community is exposed to risks and also the extent of their adaptive capacity (Davoudi et al., 2009). The exposure depends on the magnitude of risks caused by climate change. For example, the magnitude of high temperature in a heat wave is important in the risk assessment process. The sensitivity refers to the preparedness of a community in confronting risks. Vulnerability is an estimation of risk for people, infrastructure, and economic sectors. The vulnerability level varies between places and between population groups, depending on the way extreme conditions affect people (Davoudi et al., 2012). For example, flood affects certain places and population groups living in flood plains, while heat waves affect certain age groups, people with health conditions, or people without appropriate air conditioning systems. Children, the elderly, and people with health conditions are usually considered more vulnerable in extreme conditions. They are not as mobile as other groups; they are more likely to not be able to operate machines and other safety systems; and finally, their body is more susceptible to health risks (Kelly & Adger2000).
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In the vulnerability measurement the ability (capacity) of social groups to cope in an extreme condition should be evaluated. In most cases, low income groups are less prepared to confront adverse effects of climate change. They also are susceptible in post disaster situations. For example, recovery is more difficult for low income groups due to access to a proper insurance or social network.
According to the IPCC, climate change mitigation policies refer to interventions that reverse anthropogenic climate change drivers such as greenhouse gas emission or land cover change. Climate change adaptation is the action of adjusting natural and human systems to be less vulnerable in extreme weather conditions and their expected direct or indirect effects. In other words, adaptation strategies enable human communities to enhance their resiliency in extreme weather condition (IPCC, 2014). Climate change mitigation policies usually are long term strategies to slow down the pace of climate change drivers, while adaptation policies address short term strategies to cope with adverse effects. Adaptation and mitigation policies are necessary along with sustainable development and therefore, all planning hierarchies (from national to local scale) need to address them as their core objectives. Adaptation and mitigation policies should be pursued in a parallel way (simultaneously). Swart and Raes (2007) argue that these strategies do not conflict and therefore, they need to complement each other at different time scales. Planning authorities and institutions should follow these policies together in an integrated framework.
Planners not only need to define appropriate policies for adaptation and mitigation, they also need to articulate the relationships between adaptation and mitigation strategies, including conflicts, consistencies, priorities, time scale, and responsible institutions. Howard (2012) believes there is a lack of systematic approaches in the planning literature to frame the relationships between mitigation and adaptation policies. In most of planning literature, these two are being studied separately. He identifies cases in which adaptation policies are not consistent with mitigation strategies. For example, for being prepared for heat waves, air conditioning systems could be a solution while they could increase GHG emission. Sometimes, planners need to trade off consciously when they choose one strategy with some adverse side effects. Howard argues that planners should have a comprehensive understanding about the climate change science and the impacts of their decisions for both mitigation and adaptation. Howard (ibid) argues that global
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mitigation is impossible without local mitigation; furthermore, without effective global mitigation, local adaptation would be impossible.
Howard (2012) introduces some principles for planners dealing with adaptation and mitigation policies. The first principle informs the overall priority of mitigation over priority. Of course, there are situations in which short term adaptation solutions are required to be resilient against an extreme situation. However, the changing climate is the greater risk and the projections show that the human race and other species are in significant danger. Therefore, the first priority for planning in a changing climate is mitigation and the most important mitigation objective is reducing GHG emission. The second principle suggests that mitigation is the main form of adaptation. Therefore, communities should remain committed to behave and consume responsibly and be environmentally conscious.
Planning for mitigation policies need a thorough understanding of climate change drivers. Although CO2 concentration in the atmosphere is the main driver, there are other variables that play important roles. All variables that influence the Earth’s energy balance can potentially be addressed in the mitigation policies. The Earth’s energy budget will be discussed in the following section. In short, any variable that increases the radiation absorption should be in the list of climate change drivers. Figure 12: Radiative forcing of climate between 1750 and 2011 (IPCC, 2013 WGI) shows the share of each driver in the global warming process. The chart shows that greenhouse gases have the highest share in trapping more energy. Nevertheless, the IPCC’s chart does not explain the indirect effects of these drivers. For example, the albedo effects that resulted from land use change have contributed to less solar radiative forcing. Radiative forcing is the net incoming energy from the sun, typically expressed in watts per meter squared. However, land use change results in several indirect influences on climate systems. For example, a concrete surface may have higher albedo value (more reflective) compared to vegetated surface but it changes the storm water flow, humidity, surface heat, etc. Overall, the IPCC provides precise measures about atmospheric drivers but it does not provide precise measures about land use change and their consequences.
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Radiative Forcing (W m^)
Figure 12: Radiative forcing of climate betM'een 1750 and 2011 (IPCC, 2013 WGI)
Although land cover change may not directly influence the radiation and energy balance, it is usually the sign of settlement development, deforestation, etc. Urban development, settlement expansion, and sprawl affect energy consumption, GHG emission, water resources, and natural ecosystems. There is a strong stream in the planning literature, exploring how urban form and spatial structure of cities can impact VMT (Vehicle Miles Traveled). Studies such as Bertaud (2004) and Clark (2013) found that sprawled cities and metropolitan areas emit more GHG and higher densities can reduce emission per capita.
Mitigation efforts need to be integrated through all scales from international to local. In order to address the right issues, we need to identify the important drivers that can be controlled at the urban scale planning level. According to the United States Environmental Protection Agency (EPA), GHG emission depends various variables such as fuel price, winter and summer conditions, and economic situation. EPA’s data show a little decline in GHG emission, which they attributed to the shift from coal electricity generation to natural gas and hydropower (Figure 13).
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Figure 13: Total U.S. Greenhouse Gas Emissions, 1990-2012 (EPA, 2014)
The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation. According to EPA (2014), electricity production is the main GHG emission resource. Figure 14 shows the share of each sector in emitting GHG. According to this figure, there is a significant emission produced by transportation and residential/commercial sectors. Local governments and planning authorities can substantially mitigate emission in these sectors. Also, EPA (ibid) argues that land use and forestry offset approximately 15% of 2012 greenhouse gas emissions. Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions. In the United States, since 1990, managed forests and other lands have absorbed more CO2 from the atmosphere than they emit.
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Figure 14: Total U.S. Greenhouse Gas Emissions by Economic Sector in 2012
The IPCC, EPA, Post Carbon Institute, and many other important research groups all argue that mitigation policies should be pursued at local levels with an integration with national or global efforts. As Lerch (2007) argues municipalities must adapt effective policies to mitigate climate change drivers. Lerch focuses on energy consumption and believes municipalities can benefit from mitigation strategies in short and long term. For example, they can pursue building codes that are in favor of efficient energy consumption. Compact city form, public transit infrastructure, walkable and bikeable cities, energy efficient buildings, renewable energy development, and land use and open space protection policies are some examples that mostly municipalities are responsible for.
The science of climate change is well studied. However, as Davoodi et al. (2009) argue, it seems that there is less studies exploring how planning policies should address climate change adaptation and mitigation. Nevertheless, a sustainable planning paradigm could be seen as a direction to mitigate climate change trends. For example, urban infill strategies responding to urban sprawl have been tended to reduce VMT (Vehicle Mileage Traveled) and emission. According to Davoodi et al. (2009) planning theory should provide an integrated firm framework
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to direct the practice of planning more effectively. The available literature about planning adaptation and mitigation is disparate and does not provide a coherent image.
The pace of climate change is fast; our cities will encounter serious extreme weather events in the close future. This substantially changes the context of planning and requires a new prioritization of policies and aims. In other words, planning as a practice itself should be resilient to embrace climate change adaptation and mitigation actions more quickly. Figure 15 shows the conceptual framework indicating the relationships between mitigation and adaptation strategies and the health effect issues of climate change. Climate change is changing the horizon of cities’ future. Therefore, planners should make cities ready to confront this situation and more importantly, move toward mitigating current anthropogenic changes.
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Mitigation
Adaptation
Anthropogenic greenhouse gas emissions

Climate change , Changes in mean climatic conditions and variability: •temperature •precipitation • humidity •wind patterns
J ‘
Natural climate forcings (determinants): terrestrial, solar, planetary, orbital
Environmental
effects
Extreme weather
events
i—► •frequency
•severity
•geography
Effects on ecosystems: (land and sea), and on particular species
Sea-level rise: salinationofcoastal land and freshwater storm surges
Environmental
degradation:
land, coastal ecosystems,
fisheries
Health effects

*
Thermal stress: deaths, illness Injury/death from floods, storms, cyclones, bushfires Effect of these events on food yields
Microbial proliferation:
Food poisoning—SafmoneJfa spp, etc; unsafe drinking water
â–º
Changes in vector-pathogen-host relations and in infectious disease geography/seasonality—eg, malaria, dengue, tickborne viral disease, schistosomiasis
^ Impaired crop, livestock and
fisheries yields, leading to impaired ^ nutrition, health, survival
Loss of livelihoods, displacement, leading to poverty and adverse health: mental health, infectious diseases, malnutrition, physical risks
Figure 15 Conceptual Relationships between Climate Change Adaptation and Mitigation Plans and Public Health
ressource McMichael, et al. (2006)
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Urban Heat Islands
The urban heat Island phenomenon (science)
Urban areas defined as heat islands are believed to be about one to four degrees Celsius warmer than their surroundings because of built environment intensity (Corburn, 2009 and EPA, 2008). However, this is a controversial quantification because different studies used very diverse methods to measure urban heat island effects and they offer different values. The variability of findings are due to disparate definitions of urban and rural area, surface and air temperature, day and night time temperature, and averaging timelines (summer, annual, monthly, number of warm days or nights, etc.). These differences in measuring heat island effects will be discussed in the later sections. Urban heat island effects are visible and notable during the warm summer days. Urban heat islands impact communities by increasing energy consumption, air conditioning costs, air pollution, GHG emissions, heat-related morbidity and mortality, and water demand.
Urban built environments contain more buildings and impervious surfaces compared to rural or natural environments which are covered by vegetation or soil (that can keep moisture in). As urban areas develop, the landscapes change. We add more mass to the ground such as buildings, roads, and other infrastructure replacing open land and vegetation. Permeable surfaces which are capable of keeping moisture in them become impermeable (concrete and asphalt) and dry, which loads more thermal mass on the surface. These changes tend to generate higher surface temperature and store/trap the energy. As a result, urban areas become warmer than their surroundings; this is called urban heat island (EPA, 2008).
The temperature anomaly is measurable through surface and ambient (atmosphere) temperature. On a summer day, surfaces with less moisture or low albedo (such as asphalt) absorb more radiation resulting in heating up the surface. In a natural environment vegetated area absorb less temperature because of water presences. However, bare soil also may have a high surface temperature depending on its moisture level. In a summer day, the impermeable surfaces exposed to direct sunlight can heat up to 50°C while the temperature of shaded or moist surfaces would be close to air temperatures(Memon, Leung, & Chunho, 2008).
Temperature anomalies attributed to urban heat islands have different behavior in day and night. During the day, it really depends on the land cover type of the natural environment in the
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surrounding areas. Vegetated land cover or moist soil would create a cooler area compared to urban areas. Buildings, masses, and urban surfaces with their relatively higher thermal mass absorb and store energy during the daytime. At night, they emit long wave radiation and release energy into the atmosphere, resulting in higher urban temperatures as compared to surrounding areas (Akbari, 2005).
According to EPA (2008) the annual average atmosphere “temperature of a city with 1 million people or more can be 1.8-5.4°F (1-3°C) warmer than its surroundings. On a clear, calm night, however, the temperature difference can be as much as 22°F (12°C)” (EPA, 2008, P.l). Figure 16 shows daytime and nighttime temperature anomalies attributed to urban heat islands.
Figure 16: Daytime and Nighttime Temperature Anomalies Resulting in Urban Heat Island (EPA, 2008)
Eirban heat island consequences
An urban heat island is an imbalance in the climate system; therefore, it creates other consequences in natural and human systems. In this section, I briefly mention the literature available regarding urban heat island consequences.
Urban heat and public health:
Surface Temperature (Day) Air Temperature (Day) Surface Temperature (Night) Air Temperature (Night)
Rural Suburban Pond Warehouse Urban or Industrial Residential
Downtown Urban Park Suburban Rural Residential
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In the public health literature, the effect of heat is usually reviewed as an issue of heat waves. Heat waves can be exacerbated by urban heat islands. However, it is important to differentiate these two phenomena. I reviewed the impact of heat waves in the previous sections.
Urban heat and energy consumption
Urban heat island effects increase energy and water consumption significantly. Santamouris et al. (2001) found that an intense urban heat island effect in Athens, Greece can increase the energy consumption of buildings. In cases where urban areas have been warmer by 10 C°, the summer time cooling load on the electricity system could be doubled. They also found that in winter, urban heat island effects reduce the heating demand by 30%. Akbari et al (2001) found that electricity demand in cities increases by two to four percent (2-4%) for each 1°C. They measured that the urban heat island effect in Los Angeles is about 0.5-3.0°C. Considering this difference, they estimated that the electricity demand increases by 5-10% for cooling buildings to compensate the urban heat island effect. They concluded “mitigation of urban heat islands can potentially reduce national energy use in air conditioning by 20% and save over $10B per year in energy use and improvement in urban air quality” (P:295).
EPA (2008) also provides a similar energy consumption rate for compensating the urban heat island effect. Their estimation is that for every 1°F increase in temperature, the peak urban electric demand increases 1.5 to 2%. This is the same amount if we convert it to Celsius (in the range of 95-96°F or 35-35.5°C). Another problem appears when energy consumption overloads the electricity system in heat waves. Steadily increasing temperatures may result in power outages (Figure 10). As discussed before, this could cause serious harm to vulnerable groups.
Urban heat and water consumption
The relationships between water consumption and urban heat is not well stablished. I could find only one peer reviewed paper on this. Aggarwal (2012) argued that the analysis of longitudinal data using a mesoscale atmospheric model, shows that the variations in surface temperature affected water consumption in single family residential housing units in Phoenix, Arizona. They argue that each one-degree Fahrenheit (1°F) increase in temperature can elevate water consumption by 1.4%. They found that this variation correlates with lot size and pool size of housing units.
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Urban heat island and air quality
Urban heat islands impact air quality locally and regionally. Regional air quality could be affected by the increase in energy consumption and electricity demand if the main resource for electricity is fossil fuels. Local air quality would be impacted because of ground level ozone intensity. When the temperate is higher, the intensity of ozone will be higher at ground levels. EPA (2008) argued that elevated air temperatures increase the ozone formation. When other variables related to ozone formation (“such as the level of precursor emissions or wind speed and direction”) are controlled ’NOx and volatile organic compounds (VOCs) react in the presence of sunlight’ (P: 14). In an empirical study, Stone (2005) explored 50 largest American metropolitan areas and found that “annual violations of the national ozone standard were more strongly associated with regional temperatures than with the emissions of regulated ozone precursors from mobile and stationary sources” (P: 13).
Urban heat island and environmental injustice
Urban heat does not affect all social groups evenly. Harlan et al (2006) explored heat-related health inequalities. They used microclimate simulation to find out the temperature variations in several neighborhoods. This model estimated the outdoor human thermal comfort index for eight neighborhoods. The result of this study shows that the lower income and minority groups are more likely to be exposed to higher temperatures. They argued that these groups also are more vulnerable as they have less capacity to cope with higher temperatures on summer days and nights. They conclude that “urban heat island reduction policies should specifically target vulnerable residential areas and take into account equitable distribution and preservation of environmental resources” (P: 2847).
Kovats and Hajat (2008) also addressed urban heat as an environmental and occupational hazard. They argue that lower income and minority groups cannot afford implementing heat mitigating solutions such as vegetation, increasing roof albedo, etc. Furthermore, these groups do not have access to efficient air conditioning systems, insulated and well-designed housing. Accumulation of all these variables make them vulnerable in extreme heat events. Findings of Semenza et al (1996) about the characteristics of affected population during the July 1995 heat wave in Chicago proves that heat as a hazard affects low income and minorities more intensely.
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The science of energy balance
To understand how urban heat islands form we need to have a solid understanding of physics of heat transfer and the Earth’s energy balance. We need to understand how surfaces and materials absorb energy and transfer heat. In this section, first, I briefly explain the fundamentals of heat absorption and transfer. Second, in the following section, I will review the methods of urban heat island measurement and exploration, their benefits, and disadvantages.
Fundamentals of heat transfer:
What is heat? This is a fundamental question in the science of urban heat island and microclimate. Generally, most definitions of heat refer to a relative temperature difference. We may compare one object with another object and the one with higher temperature would be considered as the hot object. From another perspective, we may define a base temperature as a benchmark and anything above that temperature could be considered as a heated substance. Heat is a type of energy which is related to the energy of molecules in a substance. Heat transfers because of energy differences. Each system tends to reach the thermal equilibrium. Therefore, energy with the shape of heat transfers from the hot substance to the cold substance until they reach the same temperature. Using rules of thermodynamics, we can measure the rate and quantity of heat transfer. Therefore, the engine of heat transfer is temperature difference.
Heat transfers in three ways: conduction, convection, and radiation. Conduction is the physical interaction of two substances through the neighbor particles (molecules). For example, a hot coffee cup in a room cools down through the interaction of surface particles with air particles. The rate of het conduction through a medium depends on the temperature difference, the shape or the geometry of the medium, its material, and its thickness. For example, buildings loos energy through the conduction of walls and roofs. Figure 17 shows how heat transfers through conduction. Materials have a property named “thermal conductivity” which defines their abilities in heat conduction. Materials with higher thermal conductivity transfer heat more efficiently. Another important property of a material related to measuring heat transfer is “heat Capacity”. Heat capacity defines how much energy a material can store per unit volume. For example, this explains how much heat one cubic meter of wood can store compared to one cubic meter of asphalt.
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(r
Coffee particles with a higher aver-age khretic energy collide with the container wall and tr ansmit tlreir energy to tire surroundings.
Figure 17: Heal Transfer through Conduction (fengel & Turner, 2004)
Convection is the mode of heat transfer between a solid surface and the adjacent fluid (liquid or gas). Fluids that can move faster, can transfer heat faster. If a fluid is exposed to higher temperature in one side, its molecules get energy through surface conduction then they start to move due to pressure differences. In other words, convection is the process of heat transfer from one location to the next by the movement of fluids. The moving particles of the fluid move energy. The fluid flows from a high temperature location to a low temperature location. In urban areas, convection is one of the important ways through which surface temperature heats the air above it. Then the heated air moves around and increases the ambient temperature (£engel & Turner, 2004). Figure 18 shows the convection process.

w
O ^ J

V- J
t t w t t
Figure 18 Convection Heat Transfer: hot air has low density and rises; cool air has high density and sinks (Cengel &
Turner, 2004)
The third way of heat transfer is radiation. Radiation is the electromagnetic wave that transfers energy through emitting photons (energy) from matter as a result of the changes in the electronic
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configurations of the atoms or molecules. Radiation does not need any substance as a medium to transfer the energy. Heat transfer through radiation is the fastest (with the speed of light) type of energy transfer because photons carry the energy through space. Atmospheric particles can block or attenuate photons. Any object with the temperature higher than zero Kelvin radiates energy in the form of electromagnetic waves. The energy transfer rate through radiation is a function of the Kelvin temperature (T) raised to the fourth power (Cengel & Turner, 2004). The rate of heat transfer through radiation depends on the material of objects. The maximum amount of radiation that an object can emit can be calculated through Stefan-Boltzmann law E = soA(T)4 in which:
• E is the total emittance (emitted radiation from a surface)
• a is the Stefan Boltzmann constant (5.67 * 10"8 W/m2K4)
• A is surface area
• T is temperature (Kelvin)
• sis emissivity of the surface
Emissivity is a property of materials and explains how efficient that material is in emitting energy. Emissivity is a value between zero and one (0 < s < 1). An ideal surface that radiates at maximum rate is called a blackbody. The emissivity of blackbody is one (e=l). The emissivity of all materials in the real word is less than one. Table 1 shows the emissivity of some sample materials at 300 Kelvin.
Table 1 Emissivity of Some Materials at 300 K (Cengel & Turner, 2004)
Material Emissivity
Aluminum foil 0.07
Anodized aluminum 0.82
Polished copper 0.03
Polished gold 0.03
Polished silver 0.02
Polished stainless steel 0.17
Black paint 0.98
White paint 0.9
White paper 0.92-0.97
Asphalt pavement 0.85-0.93
Red brick 0.93-0.96
Human skin 0.95
Wood 0.82-0.92
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Soil
Water 0.96
Vegetation 0.92-0.96
0.93-0.96
Another important property of materials related to radiation is called absorptivity (a) which is the fraction of the radiation energy incident on a surface that is absorbed. Emissivity explains how well a surface radiates (emits) energy, while absorptivity explains how well a surface absorbs energy. The value of absorptivity (a) is between zero and one too. A blackbody object is also a perfect absorber (a=l). According to Cengel & Turner (2004), the absorptivity and emissivity are a function of temperature and radiation wavelength. Kirchhoff s law states that the absorptivity (a) and emissivity (s) of a surface at a given temperature and wavelength are equal. Figure 19 shows how an incident radiation can be absorbed or reflected.
Figure 19 The Absorption ofRadiation Incident on an Opaque Surface of Absorptivity (Cengel & Turner, 2004)
How does incident radiation interact with a surface?
Three things may occur when incident radiation reaches a surface. The radiation (energy) can be absorbed, transmit, or reflected (Figure 20). According Cengel & Turner (2004), the sum of these three variables are one:
• Reflection + Transmittance + Absorption = 1
Irradiation
Reflected
radiation
Absorbed <-> radiation
Transmitted radiation
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Figure 20: Incident Radiation May Be Reflected, Transmitted, or Absorbed (Pan, 2011)
I have already defined absorption coefficient (a). The wavelength of reemitted incident radiation is always longer than the incident radiation because the temperature of the receiving surface is lower than the temperature of sender surface. This is because hotter objects emit at lower wavelength. For example, the maximum energy of radiation emitted by sun at the top of atmosphere is about 0.4 pm (short wave radiation) while an object with the temperature of 300 Kelvin (26°C) is about 10 pm (long wave or infrared radiation).
Reflection is different with re-emittance. Figure 20 shows reflection not re-emittance, which is part of the incident radiation and therefore its wavelength is close to the main incident radiation. In order to measure the ability of reflectivity of a surface we use Albedo measurement. Albedo is also is a coefficient which is a value between zero and one. Albedo describes the percentage of reflected amount of an incident radiation. Albedo is a function of material, its surface color, and its roughness. For example albedo of a perfect mirror is one meaning that it reflects 100 percent of the incident radiation. According to Kirchhoff s law, surfaces with high reflectivity (or roughly albedo) have low emissivity.
These fundamentals are important for understanding the urban heat island phenomenon because cities absorb and store more heat mostly through radiation (receiving from the Sun). Table 2 summarizes the terms and coefficients we need for explaining the process of absorbing, storing, and re-emitting heat.
Table 2 Summary of Some Key Coefficient for Understanding Heat Transfer
Coefficient Symbol Description
Heat Conductivity C Explains how well a material can conduct heat
Heat Capacity HC Explains how a material can store heat per unit volume (is a measure of the amount of energy required to raise the temperature of a given volume of a material by a given number of degrees.
Emissivity E Explains how well a material can emit energy (is a function of temperature and wavelength)
Absorptivity A Explains how well a material can absorb radiation (also is a function of temperature and wavelength); a = 1- £
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Albedo (Reflectivity)
A
Explains how well a surface can reflect an incident radiation (high albedo surfaces reflect the short wave radiation coming from the Sun in the form of short wave)
The earth's energy balance at urban scale
Climate change research started with observing the evidence of change in the late 19th century. Explaining the drivers of climate change needs a strong quantitative modeling founded on physics of energy flow in the Earth’s atmosphere and on its surface. According to Stevens and Schwarts (2012), Arrhenius took the first steps in formulating the effect of carbon dioxide in the surface temperature in 1896. Although his model was still insufficient and did not consider some key issues. The research in this field has grown rapidly in recent decades. Understanding the energy flow in a system like the Earth involves numerous variables, interactions and processes that are all tied together. Study of the Earth’s energy balance or budget is the comer stone of explaining climate change processes and identifying its drivers precisely. Later efforts in the 1960s resolved some complicated issues of radiative heat transfer, especially in long waves (infrared) energy transmittance (Stevens & Schwarts, 2012).
The urban heat island effect is one of the anthropogenic climate change issues. This phenomenon is the result of changing the Earth’s landscape. These interventions on landscape, not only contribute to the global climate change but also impact regional climates which potentially exacerbates extreme heat events. The resource of energy and heat on the Earth is radiation coming from the Sun. It is important for understanding the urban heat island issue to understand how radiation coming from the Sun interacts with objects and surfaces and to identify the variables that can potentially contribute to more heat absorption and restoration.
First, I explain the global Earth’s energy budget. Then I will discuss how urban landscape influences the energy flow. Fundamentally, any mitigation action that we choose to take has to be consistent with the energy flow. Anthropogenic interventions on the Earth’s atmosphere and surface have changed the energy flow and made it imbalanced. It is clear that GHGs are the main global warming driver; however, there are other areas such as land cover that provide opportunities for climate change mitigation along with urban heat island mitigation.
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Figure 21 is a conceptual framework for explaining the energy fluxes reaching to the Earth, being absorbed, reflected, and emitted out. The estimated numbers have been updated in several studies. One of the main studies carried out by Kiehl & Trenberth (1997). The estimations have been improved due to progress in observations and evidence collected by satellite data which provides global coverage. As Figure 21 shows, the incoming solar radiation at the top of atmosphere is 341.3 Wm"2 (Watt per square meter). The radiation coming from the Sun is mostly centered in short wave and visible spectrum (0.3-0.5 pm). The Earth’s atmosphere plays a very critical role. It reflects 79 Wm"2 of the incoming radiation back to the space. The atmosphere, also, absorbs 78 Wm'2 of the incoming solar energy, which warms up our atmosphere. After reaching the radiation to the surface, 23 Wm"2 of it will be reflected and 161 Wm"2 of it will be absorbed. Totally, 102 Wm"2 (79+23) of radiation is reflected back to the space in the form of short wave radiation. The other 70 percent (239 Wm"2) of incoming short wave radiation is absorbed either by atmosphere or surface, which is the resource of heat and energy of our planet. When the Earth’s atmosphere and its surface are warmed up, they start to emit radiation in the form of long wave radiation (infrared).
The heated surface of the Earth, on average, emits 396 Wm"2 in the form of long wave radiation to the sky. From this amount 40 Wm"2 passes the atmosphere and goes to the outer space. The remaining 356 Wm"2 will be absorbed by the atmosphere. The warmed up atmosphere then emits long wave radiation to all directions. From one side it emits 199 Wm"2 radiation to the outer space. On the other direction, atmosphere emits long wave radiation back to the surface. This is where GHGs cause global warming because they absorb more short wave and long wave radiation; also, they emit back this energy to the surface; in other words, they trap energy in the lower atmosphere. According to IPCC AR5 (2013) the energy imbalance, on average, is about 0.6 Wm" 2 (0.2-1). Trenberth et al (2009) estimated the imbalance as 0.9 Wm"2. This imbalance is the amount of energy that drives the global warming and climate change at the global scale.
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Nrt jibiaibrd
0,9
Wnv1
Figure 21 The Global Annual Meant Earht's Energy Budget for the Mar 2000 to May 2004 (Wnr2) (Trenberth etal., 2009) Energy budget in urban areas
After reviewing the science of heat transfer and energy budget, we can explain what properties in urban areas can create an imbalance energy flow and result in urban heat island. As I discussed before, the difference of urban and rural areas is the landscape. In urban areas, we change the surface with materials that have a series of different properties in terms of heat transfer behavior. For example, urban areas have significant area covered by asphalt such as roads, roofs, and parking lots. Asphalt has a high emissivity value meaning that it absorbs radiation more effectively and emits it back more intensely (at long wave range); also, asphalt has low albedo value which means it reflects less short wave radiation back to the sky. On top of these, we add more mass to the environment, accumulated in a relatively small area, increasing the heat capacity or thermal mass. In other words, we are creating a large pool that has capacity of storing a great amount of heat very efficiently.
Furthermore, an urban landscape creates a rough surface (porous) that can trap radiation between buildings. Also urban landscape increases the surface area and as a result more air interacts with warm surface. This contributes to the sensible heat which is heat transfer through conduction at the surface. Another variable in urban areas is anthropogenic heat produced by cars,
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industries, and air conditioning systems. These machines and facilities release a significant amount of heat to the urban area. In later sections, all these variables will be formulated for urban microclimate simulation. Urban landscape can trap short and long wave radiation between buildings and canyons. Figure 22 is the conceptual framework presenting the interaction of radiation with masses, sensible heat, anthropogenic heat, and latent heat.
Figure 22 Contributions of Urban Landscape in Imbalance of the Earth's Energy Budget (EPA, 2008)
Methods of measuring urban heat island
In this section, I review the common and prevalent methods of urban heat measurement. I draw their advantages and disadvantages and approaches in formulating heat. It is widely believed that urban heat influences local and regional climate, changes local wind regimes, impacts cloud forming, impacts humidity distribution, and alters precipitation patterns. Many studies introduce Luke Howard (1772-1864) as the pioneer researcher identifying the impact of urban areas on local climate. He explored the climate of London (1802-1830) and published three volumes of a book titled “The Climate of London”. Identifying the urban heat island effect was based on his own collected data and temperature records of three different sites outside London. Figure 23 shows the outcome of Howard’s measurement. Although Howard’s observations implicate urban heat
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island, the condition of temperature instruments and their general local morphologies are unknown (Mills, 2008).
Figure 23 Observation of Luke Howard: the annual temperature curves (1797 to 1816) for the city (solid) and rural area
(dashed) (Mills, 2008)
One of the technical and conceptual issues of measuring or simulating urban heat is the scale issue. Urban heat island is a meteorological issue which is the outcome of several variables with scales ranged from building scale to mesoscale. For example, the material and albedo of building roofs, parking lots, and roads need high resolution data and measurement while mesoscale variables are affected by the general climate in the region such as horizontal and vertical air movements including Coriolis force, which can forcefully replace the air above a region and replace it with a different pressure and temperature. As Amfield (2003) points out, the definition of scale in conceptualizing urban heat island determines how we should quantify heat transfer between surface and atmosphere.
Most theoretical and conceptual models for observing or simulating urban heat do not integrate mesoscale and microclimate scale. Scale issue is conceptually resolved for energy flux integration and exchange (Amfield, 2003). Later, in the review of climate modeling section, I will explain Urban Canopy Layer (UCL) and Urban Boundary Layer (UBL). Available models are not able to integrate the simulation of urban heat from building scale to mesoscale. Studies such as Chen et al (2011) are examples that tried to link mesoscale models such as WRF to urban scale meteorological studies. In the next sub-section, I categorize the approaches used to study urban heat islands and discuss the advantages or the complications that could lead to flawed conclusions.
Observing heat island variables
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Many studies are built on the observation of temperature variations in urban and rural areas. Most of these studies correlate observed temperature variations with the location or spatial configurations. Amfield (2003) summarizes these observations and hypotheses in Table 3.
Table 3 Common Urban Heat Island Observations and Hypotheses (Amfield, 2003, P:23)
Empirical generalization Reference
UHI intensity decreases with increasing wind speed Ackerman (1985); Park (1986); Travis et al. (1987); Kidder and Essenwanger (1995); Eliasson (1996b); Ripley etal. (1996); Figuerola and Mazzeo (1998); Magee et al. (1999); Morris et al. (2001); Unger et al. (2001)
UHI intensity decreases with increasing cloud cover Ackerman (1985); Travis et al. (1987); Kidder and Essenwanger (1995); Eliasson (1996b); Ripley etal.(1996); Figuerola and Mazzeo (1998); Magee et al. (1999); Morris et al. (2001); Unger et al. (2001)
UHI intensity is greatest during anticyclonic conditions Unwin (1980); Unger (1996); Shahgedanova et al. (1997); Tumanov et al. (1999); Morris and immonds (2000)
UHI intensity is best developed in the summer orwarm half of the year Schmidlin (1989); Ktysik and Fortuniak (1999); Philandras et al. (1999); Morris et al. (2001)
UHI intensity tends to increase with increasing city size and/or population Park (1986); Yamashita et al. (1986); Hogan and Ferrick (1998)
UHI intensity is greatest at night Unwin (1980); Adebayo (1987); Schmidlin (1989); Djen (1992); Ripley et al. (1996); Jauregui (1997); Magee et al. (1999); Mont'avez et al. (2000); Tereshchenko and Filonov (2001)
UHI may disappear by day or the city may be cooler than the rural environs Unwin (1980); Tapper (1990); Steinecke (1999)
Rates of heating and cooling are greater in the countryside than the city Johnson (1985)
Urban heat island is a function of many variables at different scales ranged from mesoscale to building scale. In many studies the systematic complications of urban heat are ignored and the phenomenon is studied using limited factors which resulted in flawed arguments and conclusions. For example, some studies show that the intensity of urban heat is not the greatest at night times in all cases (Mirzaei & Haghighat, 2010). It could vary based on regional air flows, humidity of the region, soil type, vegetation coverage, etc. For example, Repley et al (1996) found that the intensity of urban heat is more significant in daytime compared to nighttime. The contradictory results are usually due to
Observation of urban heat (air temperature us. surface temperature)
There are two common temperature measurement methods prevalent in urban heat studies: air (atmospheric) temperature and surface temperature. Although spatial patterns of surface temperature correlate with air temperature, they do not match completely. These differences are
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due to different behavior of these two phenomena. Surface temperature is highly dependent on radiation exposure and surface materials. As a result, its spatial pattern has strong variations with sharp edges. On the other hand, air temperature is less correlated with landscape variation and geometry. Instead, air temperature highly depends on air flows and turbulence at different atmospheric layers due to convection and advection forces. Urban canopy layer (the lowest level close to surface) is more affected by the surface temperature than higher layers through convection heat transfer. This correlation is higher in a calm weather.
Observing air temperature:
Urban heat island phenomenon was first identified by observing air temperatures in urban areas compared to rural areas. The first temperature records documented for urban heat were collected by Luke Howard in the 1810s-1820s (Mills, 2008). Studies that used ambient temperature distributed a series of thermometers throughout a region to record the variations in urban and non-urban areas. Three types of equipment may be used in this approach. (1) Formal weather stations maintained by meteorological organizations (such as NOAA in the US), (2) portable weather stations that can record multiple parameters, and (3) simple thermometers and data loggers.
Each of the above methods has advantages and disadvantages. Formal weather stations collect precise data in highly controlled conditions. The provided information by weather organizations are highly reliable. They also provide historical data which makes longitudinal studies possible. However, the fact is that these stations are not systematically distributed to capture urban and rural temperature differences. In urban areas, there are limited stations, which are not located in preferable locations to explore urban heat island phenomenon. For example, Gedzelman et al (2003) used 50 National Weather Service (NWS) stations to measure urban heat island effect in the New York metro area. Another example is the study of Peterson and Owen (2005) in which they used the ambient temperature data collected by national weather stations.
Many studies have used a type of portable weather station that can be installed in a specific location. These instruments are capable of collecting multiple parameters such as temperature, relative humidity, wind speed and direction, and light or radiation intensity. The quality of these instruments ranges from armature ones to very professional and precise equipment. Figure 24 shows two model weather stations which are capable of logging temperature, relative humidity and wind speed/direction. In many urban heat related studies, researchers have installed their own
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stations in predefined locations. In the recent decade, some volunteers has installed and shared the information of these weather stations publicly. The data provided by these network is not as reliable as national or formal stations because there are different types of instruments but could still benefit studies with a better distribution for large metro areas. WunderMap2 website is an example of such a network. Examples of studies that used portable weather data loggers are Tso (1996), Unger et al (2001), and Giridharan et al (2004).
Figure 24 Portable Weather Stations That Log Temperature, Relative Humidity, Radiation, Precipitation (Rain), Wind
Speed/Direction
Observation of urban heat (surface temperature):
Using advanced spectrometers and sensors provides significant advantages in measuring land surface temperature (LST) through thermal remote sensing methods. Considering that thermal sensors can be mounted on satellites or airplanes, measuring LST is feasible for extensive regions. On a hot day with a clear sunny sky and calm weather, the sun radiation (shortwave radiation) reaches to the surface of the earth and depending on the albedo and emissivity of the materials can heat up significantly. In urban areas, impervious surfaces such as roads, roofs, and walls can be 50 to 90°F (27 to 50°C) hotter than the air, whereas moist or shaded surfaces do not receive the direct shortwave radiation and as a result remain near ambient temperatures (EPA, 2008). As surface temperature is highly dependent on direct shortwave radiation, studies measure day and night LST to understand the behavior of LST. According to EPA (2008), the average difference in daytime
2 http://www.wunderground.com/wundermap/
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LST varies in the range of 18 to 27°F (10 to 15°C) in urban and rural areas. However, the difference in nighttime LST is generally less, ranging between 9 (5°C) to 18°F (10°C).
Thermal (infrared) sensors detect longwave infrared ranges of the spectrum (9pm-13pm). The maximum radiation of objects with approximately 0°C-80°C temperature occurs in this range. The receiving radiation from an object is the function of its temperature, emissivity, and wavelength. When emissivity and wavelength are known, we can calculate the temperature of the object.
Many studies have used satellite thermal infrared images to detect LST. Imhoff et al (2010) studied the relationships between impervious surfaces and their intensity with LST. They used MODIS satellite images to capture LST. MODIS provide relatively low resolution images (1km by x 1km) for studying urban heat island. However, Imhoff et al (2010) compared several metro regions to explore how urban development might cause higher LSTs. They considered a wide range of variables such as topography and NDVI (Normalized Vegetation Index), land cover (extracted from Landsat TM images), and population data. They found that ecological contexts such as vegetation and land cover type has a significant influence on the magnitude of daytime urban heat island effect during the summers. They concluded that the presence and intensity of impervious surfaces are the main driver of urban heat islands. Stone (2001) used a high resolution thermal image (10m x 10m) collected by NASA for the Atlanta metro area. This image is captured by thermal sensors mounted on an airplane. Stone used this high resolution resource for calculating parcel energy flux (generated by surface temperature). He concluded that low density residential development produces more heat compared to high density ones.
Landsat satellites are one of the popular resources to calculate surface temperatures. Landsat Thematic Mapper (TM) has one thermal band (band 6: 10.40 pm-12.50 pm) has 120m by 120m resolution; “but products processed before February 25, 2010 are resampled to 60-meter pixels. Products processed after February 25, 2010 are resampled to 30-meter pixels” (USGS Landsat Mission Website3, retrieved on January 15th 2015). Landsat Enhanced Thematic Mapper Plus (ETM+) also provides one thermal band (band 6: 10.40 pm-12.50 pm) with 60m by 60m resolution; “Products processed after February 25, 2010 are resampled to 30-meter pixels” (USGS
3 http://landsat.usgs.gov/band_designations_landsat_satellites.php
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Landsat Mission Website4, retrieved on January 15th 2015). Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) are the most recent satellite launched in 2013. It provides two thermal band (band 10: 10.60 pm - 11.19 pm and band 11: 11.50 pm - 12.51 pm); “TIRS bands are acquired at 100 meter resolution, but are resampled to 30 meter in delivered data product” (ibid).
For example, Zhou et al (2011) used Landsat ETM+ to capture LST. They studied the influence of composition and configuration of land cover types on LST. They concluded that the composition of land cover types could be more influential in the magnitude of LST compared to land cover configuration. They found that buildings could produce the highest LSTs. Unsurprisingly, vegetated land cover types produce less land surface heat. There are many studies that used a similar methodology for measuring LST in relation to urban heat island using Landsat images. For example, Singh & Grover (2014) used Landsat ETM+, Odindi et al (2014) used Landsat OLI 8.
ASTER satellite is another resource for thermal remote sensing. ASTER provides five thermal bands which is considered very high spectral resolution compared to Landsat. Multiple thermal bands (Table 4) provides the opportunity of using more accurate algorithms (multiple split window) for calculating surface temperatures. There are many studies that used ASTER images for measuring LST in relation to urban heat island effect such as Kato & Yamaguchi (2005), Nichol et al (2009), Tiangco et al., (2008).
Table 4 Thermal Bands of^ISTER Satellite Images (Votano et al., 2004)
Band Number Spectral Range (pm) Spatial Resolution
10 8.125-8.475 90 m
11 8.475-8.825 90 m
12 8.925-9.275 90 m
13 10.25-10.95 90 m
14 10.95-11.65 90 m
4 http://landsat.usgs.gov/band_designations_landsat_satellites.php
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As I discussed in the previous sections, exploring urban heat island effects through measuring ambient temperature, surface temperature, or their combination has its advantages and disadvantages. It is very important to understand that land surface temperature is not exactly similar to the ambient temperature above that surface. Schwarz et al (2012) explored the relationships between land surface temperature (LST) and ambient temperature. They found that the location of weather stations is a crucial variable. In the evenings, the ambient temperature is higher than LST almost in all stations except those that are located in lawns. In the morning, the LSTs are very close to the ambient temperatures. Ultimately, they concluded that air temperature and LST are related with relatively high correlation (Rs~0.60). The behavior of LST and ambient temperature are the function of day time (due to presence or absence of short wave radiation) and the neighbor characteristics of weather stations.
Modeling and simulation of the urban microclimate
In order to understand how urban heat island forms we need to explain how energy comes to the ground level, is absorbed, and stored. Therefore, we need to explain how climate forms in the urban scale. In this section, I review the literature of conceptualizing and parameterizing urban microclimate. This review will shed light on the drivers of urban heat and the role of urban form elements.
Scales of Climate Study
Climate is a complicated nexus of variables and components. Studying the climate at the global scale could be a closed system. However, studying the climate at an urban scale is an open system which could be impacted by outer variables. Therefore, it is important to identify the complications of studying climate at an urban scale. The urban climate is affected by the horizontal climate context and vertical atmospheric layers.
A part of the atmosphere which could be impacted by the terrestrial surface is named “troposphere”. The thickness of this layer is about 10km. In a short term analysis (2-3 days), the affected atmosphere could be even thinner and is called “planetary or atmospheric boundary layer” (Erell et al., 2011, P. 15). Figure 25 shows a conceptual framework of atmospheric layers in urban areas:
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• UBL: urban boundary layer is all atmosphere above the built up area. According to Erell et al., 2011), the height of this layer is estimated about ten times.
• Mixed layer is the highest level of UBL which connects the higher atmosphere levels to the layers close to the surface.
• Roughness sub-layer is the next layer which connects the mixed layer to the urban canopy layer. Turbulence caused by urban geometry affects this layer.
• The lowest layer of the urban atmosphere is the urban canopy layer (UCL) and its height is equal to the height of buildings and other urban features such as tree canopies.
Figure 25 Atmospheric Layers above Urban Areas (Erell, 2011)
Urban canopy layer (UCL) is very important for microclimate formulation because it is affected both by surface properties and higher atmospheric layers. There is no consensus in defining these layers. For example, Arnfield (2003) defines only two layers: UBL and UCL;
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Mirzaei and Haghighat (2010) also discuss only two layers, while Erell et al (2011) define four layers. Erell et al also argue that even the depth of soil is important in modeling microclimate. They also argue that these layers are just a classification and in each context, depending on the properties of the terrain, soil, moisture level, etc. the height and depth of these layers would vary. In most simulations or microclimate formulations, UBL and UCL have been used to avoid the systematic complications.
Formulation of Urban Energy Balance
As I reviewed in the past sections, energy balance is the foundation of urban microclimate modeling. The basis of energy balance in urban environment is that the sum of input energy should be equal to the sum of stored and output energy (Erell et al., 2011).
Energy input = energy output + change in stored energy
The energy transfer between surface (built environment) and the atmosphere can be quantified through the estimation of energy fluxes5. The general equation (Equation 1) for urban energy balance is suggested by Oke (1988) and is used in other studies such as Amfield (2003), Mirzaei and Haghighat (2010), and Erell et al (2011).
Equation 1 Eneryg Balance of Urban Microcliamte
Q* + Qf = Qh + Qe + &Qs + AQa
Where Q* represents the net all-wave radiation, Qf is the anthropogenic heat flux, Qh is the convective or turbulent fluxes of sensible heat, Qe is latent heat flux, AQs is the net storage heat flux, and AQa is the net horizontal heat advection flux. Advection flux is transport of a property by a fluid, in this case the movement of heat by air. Oke (1988) suggested that at large scales, we can use this equation written for an imaginary surface body as a proxy for an urban built environment (Figure 26).
5 Energy flux is the rate of energy transfer; Its unit is watt per unit area (wm2).
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Mixed Layer
net sensible latent storage radiation heat heat heat
T
Roughness sub-layer
Urban Canopy Layer ^
L'tm
, i / i
anthropogenic
heat
[75
O
Surface
Layer
! ^ ^ ^ advection
sub-layer | ^ I
^ | 0- 0„ Q£ AOs ' |
Figure 26: Conceptual Framework of Urban Energy Balance for Microclimate Modeling (Erell etal., 2011)
Radiation plays the key role in this equation. Erell et al. (2011) separate radiation into shortwave and longwave radiation. They suggest the Equation 2.
Equation 2 Radiative Exchange
Q*= absorbed radiation + emitted radiation
Q* = {Kdir + Kdif){l-a)+Ll-L\
Where Q* represents the net all-wave radiation, Kdir is direct radiation (shortwave incident solar radiation), Kdifis diffused short wave radiation that is reflected by other materials such as building walls, atmosphere, clouds, etc., a represents emissivity of the surface (or albedo), L[ is the incoming longwave radiation emitted by atmosphere or other features in UCL, and L| is the emitted longwave radiation from the surface (Figure 27). To simulate microclimate in urban areas, depending on the scale of the study, we need to aggregate the influence of each feature (buildings and surfaces) on radiation absorption, heat storage, and radiation emittance. To relate urban geometry and morphology to microclimate modeling we need to understand how features of urban form influence on the components of Equation 1 and Equation 2.
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Figure. 27 Shortwave (Direct and Diffused) and Longwave Radiation (Erell etal., 2011)
Urban energy balance components and urban geometry (form):
In this section, I will review the approaches of urban surface interaction with microclimate components and variables. This review sheds light on the urban heat island generation processes. Identifying urban heat island drivers will help in proposing effective methods for heat mitigation as well. The following sub-sections explain the role of urban geometry and features on gaining, storing, and emitting energy.
Shortwave radiation (solar incident radiation) and diffused radiation coming from the atmosphere:
As I reviewed in the Earth’s energy balance section, the main resource of energy is coming from sun. The annual average of radiation at the top of atmosphere is about 347 wm2. When this radiation in shortwave range (high energy) reaches to the surface of an urban area, it interacts with the materials. Two main processes may occur. The incident beam may be absorbed or reflected. As I reviewed in the “Science of energy balance” section, the quantity of each process depends on the properties of surfaces.
Absorption coefficient or emissivity defines how efficient a material can absorb radiation energy. Table 5 shows the emissivity of some materials. As emissivity is a function of wavelength and temperature, there is no absolute value for each material. The number, however, helps to
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compare the efficiency of absorption and emission of different surfaces. One of the key issues in assessing the way urban surfaces interact with radiation is the emissivity of the surface.
Table 5 Emissivity of Some Materials (Infrared Thermography Website6, Retrieved December 2014 & Erell etal., 2011)
Surface (material) Emissivity Albedo
Asphalt 0.94-0.96 0.05-0.20
Concrete 0.71-0.90 0.10-0.35
Brick 0.90-0.94 0.20-0.40
Corrugated iron 0.13-0.28 0.10-0.16
white paint 0.85-0.95 0.70-0.90
Black paint 0.90-0.96 0.10-0.30
Glass 0.80-0.94 0.70-0.90
Forest (deciduous tree canopy) 0.98 0.07-0.20
Grass 0.96 0.15-0.30
Soil (wet) 0.92-0.95 0.10-0.25
Soil (dry) 0.80-0.95 0.20-0.40
Reflection is another process that occurs for an incident beam. The more a surface reflects the incident beam, the less energy remains for the absorption process (regardless of its emissivity value). Albedo is an important property of materials that defines how effective a surface reflects the incident beam. Table 5 also shows the albedo of different surface types. The higher value of Albedo makes a material a better reflector. Another property of urban surface that impacts reflection is urban geometry. In urban areas an incident radiation may be reflected several times by building facades. This is called the “canyon effect”.
The shape of urban canyons and their direction plays an important role in radiation penetration and reflection. Arnfield (1990) explored how canyon ratio and orientation can influence solar access and consequently solar radiation gain. In this study, Arnfield numerically explored the how different variables of canyon form and elements mitigate temperature for pedestrians. He concluded that street ratio and orientation, and building facades are some potential variables that planners and designers could utilize for a climate responding design. Ali-Toudert & Mayer (2006) studied the influence of street aspect issue (height to width ratio) and street direction on urban microclimate. They used ENVI-met microclimate modeling application to simulate different scenarios in a city in Algeria as a case study with hot and arid climate. They found that street ratio 6
6 http://www.infrared-thermography.com
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and direction has a strong influence on the temperature of the canyons and higher street ration (H/W) create a more comfortable temperature in the canyons. Bourbia and Awbi (2004) carried out research to measure shade coverage and its impact on creating a more comfortable temperature. They summarized that the North-South street orientation with street ratio of 1.5 (H/W=1.5) and higher can produce shade that covers 40 to 80 percent of street area.
Erell et al (2011) argue that most physical and numerical models, generally, predict a higher albedo compared to the values suggested by experimental and field studies. This is because of the complexities of urban environments, different fa9ade materials, vegetation, people and activities, etc. Studies using remotely sensed data show that the average albedo of cities range from 0.09 to 0.27 (i.e. Brest,1987 and Erell et al., 2011; Taha, 1999; Arnfield, 1982). The albedo of most cities located in North America and Europe ranges about 0.15 (±. 05). Some North African and Middle Eastern cities have higher albedo (0.3-0.4) “possibly because of uniform, low rise” and integrated urban fabric (Erell et al., 2011, P:32).
Figure 28 The Role of Street Ratio in Reflection of Solar Radiation (Erell et al., 2011)
Sky view factor (SVF) is an index that has been extensively used to measure solar access. Erell et al (2011) explain how SVF influences radiation gain and reflection. Figure 29 and Figure 30 shows the conceptual framework for measuring sky view factor (SVF).
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SVF
Figure 29 Sky View Factor Measurement Method (Erelletal., 2011)
SVF JCtiky Actual JOSiyView 2D
FieU ttcw Mrlwr> SfcerEagraphk
DWn SVF Ceorwtr?' Scanf
059 0jfi2 * T
D.2< 020
Figure SO SD Sky View Factor Measurement Method (Erell el al., 2011)
I—*—I


Through reviewing the literature implicating the physics of radiation reflection, we can extract the following rules:
• The fabric of a city can create a rough surface (compared to plain areas). Increasing density (built environment density) can contribute to the roughness of the surface. Some studies have proposed methods to measure the surface roughness. In this section, the roughness is considered as a variable influencing radiation reflections; in a later section, I will review the influence of surface roughness on air movements and turbulences. Several studies used the surface roughness coefficient to model the influence of surface shape on short and long wave radiation (Adebayo, 1990; Mills, 1997; Amfield, 1984; Verseghy and Munro, 1989).
• Building height: building aspects reflect the radiation back to the ground. Therefore, a building has more vertical surface to capture radiation and reflect it. Also, tall buildings create a deeper urban canyon. For a given street, a higher building (a narrower canyon) traps radiation through multiple reflections (from one side to the other side) and as a result increases the absorption (Erell et al., 2011).
• Uniformity and integrity of buildings: a more integrated body of buildings can reflect the radiation more effectively. Building height homogeneity is another variable that can increase the reflection. Urban fabrics with varying building height are less efficient in reflecting the radiation back to the space.
• Street orientation: the general (dominant) street orientation is related the extent to which building facades are exposed to solar radiation. As Ali-Toudert & Mayer (2006) found, the street orientation does not a significant role in the temperature of street canyons. Nevertheless, they found that East-West streets could be marginally warmer than North-South street orientation.
• The material of building facades: building fa9ade could be made from transparent materials such as glazed walls. As a result, radiation can pass through and be absorbed in the building interiors. Reflective but not absorptive materials can direct radiation to the street surface and contribute to higher temperatures.
• Roof materials and their albedo: the color and type of material can also affect albedo. Lighter colors have higher albedo.
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Long-wave radiation (emitted radiation from the surface):
As discussed in the science of heat transfer section, Stefan Boltzmann Law states that any object with a temperature higher than zero kelvin (-272.15°C) emits energy through radiation. Therefore, all features and elements in urban areas emit radiation back to the atmosphere. This energy loss helps cities to cool down especially over the nights. This energy will also heat up other features in urban environments such as buildings and its reflection will reach to other surfaces as well. Therefore, all variables discussed for short-wave radiation, will be important in heat flux modeling. For measuring long-wave radiation the emissivity of a material play an important role.
Figure 31 Long-wave Radiation Emitted from Surfaces
Convective sensible heat flax:
If the temperatures of surfaces and atmosphere are different, then the energy moves from higher temperature toward lower temperature. Convection is the movement of air. The size of convective heat flux depends on two variables: (1) the magnitude of the temperature difference between surface and adjacent air; (2) the resistance to heat transfer. Erell et al (2011) defines the heat transfer equation as:
Equation 3: Convective Heat Transfer
Qh = hc(Ts — Ta)
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Where Qh is the rate of convective heat exchange (Wm-2), hc is the convective heat transfer coefficient (Wm'2K4) and Ts and Ta are the temperature of the surface and the air. In this equation the complexities are because of convective heat transfer coefficient (hc) because it is dependent on the quality of air, air flow speed, and the geometry of the surface. Some empirical studies have defined hc-coefficient. For example, Clark and Berdahl (1980) proposed some values for different conditions that could be used as a general rule. They proposed he as 0.8 if the wind speed is very low (less than 0.076ms"1) and as 3.5 when the surface is warmer than ambient air and wind speed is lower than 0.45 ms'1. Erell et al., (2011) provide a summary of the proposed coefficients for several conditions. Most models estimate the convective heat transfer coefficient for a simple and flat surface while in the urban environment, surfaces have complex geometry. Most microclimate models ignore these complications. One important issue that should be considered here is that the complex geometry of urban fabric can decrease the wind speed close to the ground and as a result can increase the convective heat flux. Also geometries with higher exposed faces (area) can transfer heat more effectively that flat surfaces).
Turbulent sensible heat flux:
Air turbulence or wind flow moves the molecules and particles above urban environments. The heated air (adjacent to the ground) moves around and carries the warmer or cooler air to other places. Urban fabric influences the wind flow on the ground (UCL) and in the sub-layer (UBL). For measuring turbulent sensible heat flux both horizontal and vertical movements are important. Modeling air turbulence is extremely complex and high resolution simulations require significant computational power. As the wind patterns in a region are usually diverse in different seasons, it requires neighborhood scale simulation to understand the function of urban fabric in impacting air turbulences.
Computational fluid dynamics (CFD) is a common approach to simulate wind flow in urban areas. Some CFD models calculate air pressure, speed, and direction and their relationships with temperature, radiative heat fluxes, and latent heat fluxes (presence of water and vapor). Mirzaei and Haghighi (2010) argue that CFD models can produce more accurate results. However, considering the amount of details needed as inputs and modeling requirements (computation power) running CFD microclimate models could be a challenge. Mirzaei and Haghighi (2010, P: 2195) argue that: “On the other hand, theoretical problem is related to the unmatched temporal
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and spatial resolution of the phenomena which occur inside a city. For example, atmospheric and canopy- scale turbulence cannot be modeled in a same scale of time and length”. To solve the scale issue, most models are designed for two scales: (1) mesoscale and (2) micro-scale. Several studies used CFD to explore how form can influence microclimate in cities (i.e. Capeluto & Shaviv, 2002; Ramponi & Blocken, 2012; Hooff & Blocken, 2010).
Latent heat flux:
Latent heat flux is related to the energy absorbed or released by moisture of soil, biomass, surfaces, and atmosphere. Latent heat is important in the process of precipitation or evaporation. From the urban form perspective, permeable surfaces can keep soil moisture and mitigate surface heat. Impervious surfaces, on the other hand, are dry and can potentially heat up quickly. In addition, vegetation adds moisture to the air through transpiration and mitigates heat through latent heat flux. Plants also absorb moisture from deep soil and bring it to the ground. Tree canopies not only create shaded area, also absorb heat through evapotranspiration (Erell et al., 2011). In some studies, the amount of vegetation in urban areas and permeable surfaces are used to estimate latent heat coefficient, (i.e. Arnfield, 2003; Takebayashi & Moriyama, 2007; Masson, 2000).
To incorporate latent heat in microclimate simulation, some studies used water budget through estimating inputs and outputs. For example, Takebayashi and Moriyama (2007) used water budget to simulate the contribution of green roofs in heat mitigation. In another study, Brethier and Andrieu (2006) parameterized water budget model in urban areas. Also Nakayamaa and Fujita (2010) used a water budget model to measure the influence of water-holding pavements in the heat budgets of urban areas.
Thermal storage:
The absorbed heat is stored in the material and mass of the objects and surfaces. Each object has a capacity to store heat as a function of heat capacity coefficient and its size (£engel & Turner, 2004). Since the amount of stored heat plays a key role in energy budget of the system, we need to understand the amount of stored heat. Stored heat usually makes objects warmer than the ambient air over nights. As a result, these objects start transferring heat (through radiation and conduction) to the ambient air. Over a daily cycle (24hours) the storage flux is usually minor
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because surfaces gradually accumulate heat in summers and release it in winters. If we ignore the yearly variation, the daily balance would be zero (gain over day times and loss over night times).
Storage heat in urban areas (or heat capacity) is usually measured through assigning an average for each object type in urban areas. It is usually very difficult to assign a precise number to each object. Erell et al (2011) suggest that we could estimate an average value for each object type. They provide a list of values for each type (Table 6). These estimated numbers simplify calculation of thermal storage heat flux in microclimate models. This helps to classify objects in urban areas and assign the estimated values to them.
Table 6: Thermal Properties of Typical Objects and Materials in Urban Areas (Erell et al., 2011)
Material Remarks P c C k K P
Density Specific Heat Thermal Thermal Thermal
and heat and capacity conductivity dlffoslvlty admittance
{kg iiH) {J kg-' K-) and and and and

Naniral soils:
Sandy soil <40% pore dry 1600 BOO 1280 0.30 0.24 620
space) saturated 2000 1460 2960 2.20 0.74 2550
Clay soil (40% pcire dry 1600 690 1420 0.25 0,18 600
space) saturated 2000 1560 3100 1.58 0-51 2210
Peal soil {80% pore dry 300 1920 580 0.06 0.10 190
apace) saturated 1100 3650 4020 050 0.12 1420
Water pure, at 4“C 1000 4180 4180 0.57 0.14 1545
Man-made construction materials: «L
Asphalt 560 800 1940 0.75 0.38 1205
Budding brick 1970 800 1370 0.83 0.61 1065
Concrete dense 2300 650 2110 1,61 0.72 17B5
Polystyrene expanded 30 0.88 0.02 0,03 1.50 25
Steel mild 7630 500 3930 53,3 13.6 14,475
Anthropogenic heat:
Human activity in our modem world requires energy. We burn fossil fuels to heat up or cool down buildings and to run cars and industries. This energy produces some work (machinery functions) and heat. Erell et al (2011) formulated the magnitude of anthropogenic heat flux through three main variables:
Qf = Qv + Qb + Qm
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Where Qf is total anthropogenic heat flux, Qv is the sum of inputs form vehicles, Qb is the sum of heat produced by buildings, and Qm is the sum of heat produced by metabolism. In this approach, the heat produced by industrial activities will be still considered in heat produced by buildings. Ichinose et al (1999) measured the spatial distribution of energy consumption and its contribution to urban heat island. They identified the energy consumption and heat generation of different sectors such as households, commercial, manufacture, transport. As transportation is one of the heat generators in urban areas, the spatial structure of a city could be a key variable which influences the amount of VMT (Vehicle Miles Traveled). In general VMT could be a good measure for estimating Qv. Klysik (1996) carried out an experimental study to measure the anthropogenic heat flux of different neighborhood types in Lodz, Poland. For example, he measured that the “new areas of blocks of flats (about 30 Km2) have a mean annual flux of 35 Wm'2”. Also he found that the mean annual flux for central part of the city which has some industrial uses are about 40 Wm" 2 He also found that the winter anthropogenic heat flux in winters are higher than summers for this city.
These studies show that we could assign an average value for each land use type or for each neighborhood type to estimate the anthropogenic heat generated by buildings (Qb). There are also estimates for VMT in each city. The Census Bureau provided VMT at census block groups in 2000 which could provide a fairly precise spatial distribution of vehicle related anthropogenic heat flux in cities. Heat released by human metabolism and presence in urban areas is a minor proportion of anthropogenic heat flux. Erell et al (2011) believes that this number is only 2-3 percent of total anthropogenic heat flux. Most studies have ignored this parameter. Erell et al has summarized the suggested estimated measures of anthropogenic heat fluxes. Table 7 shows the average annual anthropogenic heat flux for several cities. For example, Los Angeles, CA has a relatively high per capita of energy use compared to Vancouver. This high per capita in Los Angeles is mostly because of high VMT.
Table 7 Average annual anthropogenic heat flux (Erell et al., 2011)
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Urban sraa Latitude Year Pop. density (persona km-1} Per capita energy use (GJyr1) Qr (W nr1) Q‘ (Wm-) CVQ*
Manhattan 40:N 1965 26,800 169 159 93 1.71
Moscow 56aN 1970 7.300 530 127 42 3.02
Montreal 4FN 1961 14,100 221 99 52 1.90
Budapest 47=14 1970 11,500 116 43 46 0.93
hong Kong 22‘N 1971 37,200 28 33 -110 0.30
Osaka 35=14 1970-74 14,600 55 26 n/a n/a
Los Angelas 34 tJ 1965-70 2,000 331 21 106 0-19
West Berlin 5214 1907 9,600 67 21 57 0.37
Vancouver 4S°N 1970 5,400 112 19 57 0-33
Sheffield 53»N 1052 10.400 58 19 56 0.34
Fairbanks 6414 1967-75 550 314 9 16 0.33
Urban heat island mitigation
Most of the available literature about urban heat mitigation is focused on increasing the albedo of urban surfaces including roofs and pavements through using light colors and high albedo materials. Another widely proposed solution has been urban forestry or planting vegetation. Akbari and Huang (1987) studied the potential of vegetation in reducing the use of summer-time cooling systems in residential buildings. This research shed light into the ways landscaping impacts microclimate of cities and as a result the energy consumption.
Rosenfeld et al (1995) reviewed the mitigation programs in Florida and California. They suggested that any heat mitigation program needs (1) to run test procedures for cool materials, (2) to assemble cool materials databases to guide and support the building development industry, architects, industries, and developers, (3) to incorporate cool roofs and tree canopies to build energy performance codes and other amendments, (4) and to offer incentives to complement standards and codes. They also measured the impact of cool roofs and higher albedo roof colors in reducing energy consumption. Their experimental studies in California and Florida showed that cool roofs can reduce the energy use by 20-40%. Rosenfeld et al (1995) enumerated a number of policy programs that could encompass heat mitigation policies.
Bretz et al (1997) studied Sacramento, California. They estimated that about 20% of the buildings and 10% of roofs have low albedo. They estimated that if the albedo of these surfaces were elevated, the overall albedo of Sacramento city could be raised by 18%. This improvement in albedo could produce a significant saving (about 10%) in energy consumption.
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Rosenfeld et al (1998) argued that in Los Angeles, the annual residential air-conditioning bills can be reduced by about $100 M through adopting strategies such as increasing the albedo of surfaces and planting shade trees. They argued that this saving results in the reduction of emission and consequently smog in Los Angeles’ weather, which benefits the city indirectly. They estimated the indirect benefit could be about $360M.
Takebayashi and Moriyama (2007) study some variables including the surface temperature, radiation, water content ratio, etc., in relation to green roofs and high albedo roofs. After comparing different surface types they find that on a surface with high albedo (white paint), the sensible heat flux is small because of the low net radiation (most portion of the shortwave radiation is reflected back to the sky). On the green surface, the sensible heat flux is small because of the large latent heat flux (through evaporation) although the net radiation is large. This study, through a numerical modeling, shows that high albedo and water contents can significantly reduce urban heat and should be addressed in mitigation policies.
Akbari and Rose (2007) studied four major US metropolitan areas at high resolution to measure the surface type precisely. They examine the land use and land cover types in urban areas and find that about 29-41% of the area is covered by vegetation, 19-25% is covered by buildings, and 29-39% is covered by paved surfaces. They find these surfaces a potential area of change and suggested planting vegetation and increasing the albedo of surfaces as some viable solutions for mitigating urban heat.
EPA (2008) summarizes that vegetation and green/cool roofs are the main heat mitigation strategies considered by standards and policies. However, they mention heat mitigation through modifying urban geometry could be a potential area that has not been considered well.
Memon et al (2008) carried out a review study and summarized the proposed strategies for heat mitigation. They also studied the potential temperature reduction and energy saving. Again, they focused on increasing albedo and vegetation as the main strategies. Urban geometry and morphology was not among the variables they reviewed (
Table 8).
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Table 8: Proposed mitigation strategies, maximum potential temperature reduction, and possible energy savings (Memon
etal., 2008)
Mmj;iirinri measure Mut, temp, reduction i°C) Reported savings Reference
Wj-sl.sliiwi. lighter cellar 3.0 Rniimiiidd e? ui., 1WS
of paving ;im5 cooler rtinfs
Plnnl inj£ and veg^l-uion i * - Tnng frl (ii, 2005
Plnnting .mil vcgahUian 1 ^ - Cn 199H
RcjJni'jnp .mi hropogeoic 1,2 APS. Kikqpwi! a oi, 200b
heat and planring vejjrruHnn
Plum inland vegetation i j (Vi. Astrie i’( ffJ. I99R
Plnntinji nnd vcgat.j'icn - 10$ Yn and Hien. 2(500
Proper ventilation - JOS Kolokwnmi <7o(„ 200d
Vegetation and suitable alhedn 20 10$ Turin el itf, IW0
OiF air-i!ondiu Planting and vegetation - - Spronkcn-Smilh ti i?f, ?(X>0
Red ucin'! anthiopc^mic heat and energy - - t'rano etal,, 1990
consumption, improvement In building design
Roof spray reding L3-L7 (ceiling temperature! electrical consumption Jnin and Rao, 1074
Flow of water over roof - - Sodhac-'n/., 1080
Roof pond, i-oof spray odoling and - - Tiarai fr juoviiig water over roof
Shades, Hrghlv reflective materials. - - Ynmamoto. 2(106
Open ;n>J air.1 spaces, reduce hear release from buildings etc.
Green -.aid biglilv rcfltective fixrti - - Takehavaslii and Men iyafna* 2007
Humidification and alncdn increase - - lima et at., 2uiir!
J^tuLovuLiaui: C&fljopics - - Golden etui.. 200,'
-. Jiiti. It is evident that urban mitigation policies are highly focused on albedo and vegetation. Although there has been good research identifying the role of urban geometry on forming urban heat island effect, most studies have ignored the influence of urban morphology in heat mitigation. One reason could be related to easier process of increasing roof albedo or planting vegetation compared to modifying urban form and morphology needs a long term plan and raises highly complicated policy issues. Another reason could be that most of these studies are coming from engineering or environmental study disciplines and the planning dimension is very weak. Planners need to study the role of policy and space making in heat mitigation.
Urban heat island mitigation in policy documents in Denver
As discussed in the previous section, most mitigation strategies were focused on increasing vegetation and surface albedo. This is also a visible track in policy documents. As urban heat mitigation is a relatively new issue, in most planning and design policies there is no direct attention or intention to address the urban heat issue. In recent years, adaptation and mitigation plans or climate action plans (which are mostly advisory not mandatory) are raising the urban heat issue. In this section, I briefly review the climate adaptation and mitigation plans.
The City of Denver prepared its first Climate Action Plan in 2007 which was mostly about reducing GHGs. In 2014, a new Climate Adaption Plan was published. Contrary to other cities’
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climate action plans, an increase in temperature caused by urban heat island effect is one of the main concerns of this plan. This plan also has addressed the possibility of extreme heat events in the Denver Metro area. In that report, the literature of urban heat island and extreme heat events is reviewed with the support of some evidence in the region (Table 9). However, in the proposed strategies urban heat island mitigation is limited to “Reduce urban heat island effect through infrastructure such as shade trees, urban gardens, green roofs, and lighter colored hardscapes” (City and County of Denver, 2014, P:75). These tasks are assigned to Department of Public Works (DPW). Denver’s climate action plan suggests that building codes should address issues related to roof colors and materials issue. Other suggestions are related to adaptation to extreme heat events. For example, the plan suggests a weather advisory and notification system to notify high risk populations. They also suggest preparation strategies for emergency services, urban infrastructure, public cooling shelters, and education.
Denver Climate Action (2014) also suggests some mitigation strategies including:
• Preparation of a tree and shade master plan,
• Offering a list of approved trees for planting in public realms,
• Preparation of storm drainage master plan,
• Promoting the energy efficiency of buildings and reducing anthropogenic heat,
• Installing high-albedo hardscape when resurfacing roads, multi-use paths, and city parking lots, and identify life-cycle costs associated with concrete vs. asphalt,
• Requiring permeable pavement for a portion of parking lots larger than one acre, and
• Integrating climate change into planning and zoning considerations.
Overall, the Climate Action Plan (2014) proposes some good strategies and directions. However, this plan needs to translate to codes and policies that could change the general planning and design practice. It seems the distance between setting appropriate goals and objectives and policy tools is not filled yet. One of the main strategies of this plan was “integrating climate change into planning and zoning considerations”. The latest zoning which was adopted in 2010 suggests promotion of urban vegetation but still does not force heat mitigation in practice.
Comparing the climate action plans for Boston (2014), Los Angeles (2012), and Denver (2014) reveals that Denver has taken a very progressive approach in paying attention to urban heat
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island effects and heat waves. Denver proposes some significant strategies and objectives which are consistent with the current literature. Los Angeles and Boston do not even consider urban heat mitigations in their plans. Although Denver’s plan is a considerable move in identifying and addressing the urban heat issue, there is a gap between high level goals and objectives and policies.
Table 9: Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of Denver, 2014)
CHm*gi Impact Prtortty Vulnerability Affected iTepartrvancs Sector
Higher energy corsumpocn end demand in Cne y.rrrrcr months- LXaS. L'tH, UiA, LHU. OHS' EulUngs and knergy
Higher maintenance and equipment: costs-to' Denver bdldingi LXii, OfcU*. CPU" tuiUnqsandbnarqy
Hiiikinij ■ l—■■h|ii ■■Ih'kLii K ii:i1 hsIiIihs-. iiij Iii’hIh : liH't_p* scan ares or m. cm* lliiiiiijs hii:I 1"iH-rejp
â–¡ttfruca in nudity of iv&u)4wdrtMl rumforr m iKke-^l occupant comfort in build r^mp-eablo productivity â–¡pw cm. nm. Dta. DPUDHA* HMhh arid Human Services
Ert'cme bear. events affecting vulnerable populartione CPO.DEH.DHS.CW Health and Human-Services
Increase in Increase in vector borre Diseases*1^ creased 'use of pesttodcs OEKCtWl HeaHh and Human berviccs
tcmpcacurc and iiiLmii I'M ivLirjd All SCI Increase m r>_rr£cr and'ar severity ct high az-ane daw LtH, UHHA* Hearth and Human Services
CJ%al enq rq crwronmcritai requatrans LI A Hearth and Human SfVvkAC
PpjiiLlmy 1 uii Hi' l:i 1‘N'.-iiliqMiiHi • r* aLh|: 11 i:iii ouugles rm.nw 1 ami lit* m-*i Tiansponacen
Dk-l ijn oandMdc nor r*iJ-t^>iiM r liman fl lung* Gimrte induced in-and out- mrgiacionaf wor*foroe C€D, SfdO' Land Use and
Stress on 1rees and urban landsaapng DPR Urban Nitu-el Kcsocrces
Wavnng atseium and late- :-.stems atlecing Kj.anc spe:K5 and huran rceremion DHH, U=H Urban Nacuat ItesowcB
Hiqner waterdcma-pci and pnwnc;* possibi: foqhcr cost rsf waur and tancumartan in summer month! CMJt UkH, CPH, LJW’ Wider Lccsumpban
HhiIik-mJ «- IncrMtfd thiwr nr pasts. invars]** spates and rue o Conclusion of microclimate section
Climate change is causing extreme situations harming natural and human systems. Climate change drivers and consequences are strongly related to energy use, transportation behaviors, and development patterns in urban environments. Therefore, there are two main tasks for planners from this perspective. First, how planning and design policies can mitigate climate change; second, how planning and design can make cities more resilient and adaptive to minimize damages. Considering these tasks, climate change mitigation and adaptation should become (if they are not yet) two of
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the main priorities of planning policies. This strongly entails the reframing of planning theories, goals, and objectives. Even sustainable development, as the current dominant planning paradigm, does not meet all climate change mitigation and adaptation strategies. This means, revision of application review processes (appraisal processes), main policy tools, growth control strategies etc. also need fundamental modifications. Planners should revise planning theories, techniques, methods, education, and ethics to respond to the emerging issues. Also, planning research needs to scrutinize any planning policy or development strategy to highlight the ways policies and development strategies influence climate change drivers and effects in short and long terms.
Climate change exacerbates both the urban heat island phenomenon and heat waves. Except for the anthropogenic heat flux (a small portion of total heat flux related to urban heat island) produced by mechanical processes such as cars, industries, and heating/cooling systems, urban heat island is mostly the result of built environment configuration. Nevertheless, overlapping effects of heat waves and heat islands could be a significant risk in urban environments. There is a potential for improving urban microclimate through regulating form and built environment elements.
The science of urban heat is well established now. The drivers of this phenomenon are identified in the literature. Heat mitigating strategies such as increasing albedo and vegetation are highly emphasized. However, other strategies and elements such as urban canyons and building forms are less studied. There remains a gap in the literature in translating the identified strategies to planning and design policy and practice. Urban heat island research has been mostly pursued in engineering disciplines and there are few studies from planning perspective. In general, urban heat is not well formulated in the planning and design discipline. Planning scholars need to connect the scientific aspects of this phenomenon to mitigation practice.
To conclude and summarize this section, I provide a list of urban form elements that science shows could influence heat absorption, storage, and reflection (emission). This list will be my guide to explore policies which could influence the microclimate of cities.
Table 10 Urban form elements and microclimate modeling
Form Element Variable Influenced Energy Fluxes
Surface materials (3D environments) Albedo Reflection/absorption of radiation
Emissivity Absorption/emission of radiation
Conductivity Advection heat flux
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Impermeable or permeability of surface Latent and radiate heat flux
Moisture contents (indicating latent heat) Latent heat flux
Mass (buildings) Total mass on the ground being capable of storing heat (heat capacity) Conductive heat transfer
Urban Fabric Orientation of streets and buildings (Radiation gain in facets and aspects) Radiative heat flux
Urban canyons (sky view factor) (street width, building heights) Radiative heat flux
General surface roughness of a city (homogeneity and integrity of building and urban fabric) Radiative heat flux, advection flux, convection flux
Surface Geometry (homogeneity and integrity of building and urban fabric) Radiative heat, advection, convection
Landscaping Vegetation (type and cover) Radiative heat, advection, latent heat, convection
Anthropogenic heat Number and type of cars, trucks, and buses (burned fuel). Anthropogenic heat flux
Heating/Cooling systems of buildings Anthropogenic heat flux
Machinery used in industries Anthropogenic heat flux
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A general literature review of planning and design codes and standards in urban
development
In this paper, I review urban development policies with an emphasis on downtown development. Although this is a general literature review about development polices, I highlight policies that could influence urban microclimates. I discuss historical and political contexts of policies to inform the processes through which they are shaped and implemented. For example, zoning is being used extensively to control growth and development in most American cities; understanding how zoning is devised and its main goals and conflicts will help to criticize its current function as a development control tool. The literature review in relation to policies which shape urban form will help me to formulate the relationship between policy and heat mitigation. I focus on policies such as zoning, subdivision regulations, and design guidelines that shape urban morphology. The way different form elements influence urban microclimate is extensively discussed in the first paper of my literature review, “Climate Change and Microclimate.” After reviewing the literature of development control policies and microclimate, I will be able to discuss how policy can change microclimates of cities and the future direction that would help planners and designers to mitigate urban heat island effects.
In this paper, first, I review the literature of urban design theories, the current challenges of urban design, and the future challenges, paradigms, and conflicts. I review urban renewal approaches and downtown development policies. Second, I review the general literature about urban codes and standards. Third, I review the subdivision regulations. Fourth, I review zoning policies and codes, their types, and political economic issues. The fifth section is about design guidelines. Finally, the last section is a discussion about the policies that are designed to mitigate heat.
Design theories
Reviewing urban design approaches benefits this paper because it highlights strategies and methods dealing with the design and regulation of public realms. We need to depict the direction in which design theories have evolved and the paradigms that could be dominant in the future. Key public spaces in each city are usually located in downtown areas; therefore, activity and built environment characteristics matter for any policy evaluation in downtowns. Policies and economic forces have been among the main drivers in shaping American downtowns. Policies usually are
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founded upon planning and design theories. The way we frame urban design as an issue affects the practice of design and policy making.
Urban design, with its current meaning, was a response to rational design and planning approaches in the modern era (Lang, 2005). Before and during the modern era, many efforts in planning and design influenced the design and planning practice. For example, Garden City by Ebenezer Howard (1965), and the Neighborhood Unit plan of Clarence Parry (1929) proposed clear strategies for public realms and configurations of built environments. Critics of rational planning and design efforts encouraged planners to focus on social and economic aspects of planning rather than physical design (Fainstein, 2010). For example, public resistance and social activism encouraged by Jane Jacobs (1961) directed planners toward advocacy planning focusing on the politics of planning and theorizing planning as public and political activity (Campbell & Marshall, 1999).
Most research projects and studies related to urban design are project oriented (case oriented). Each project provides new experiences, successes and failures. Lang (2005) elaborately explains the nature of urban design and its domain, typologies, and procedures through examining these projects as case studies. As illustrated in Figure 32, he categorizes typologies of urban design through ‘a three-dimensional matrix of types in terms of (1) the design and implementation process (2) the product type and (3) the major paradigm that structures the process and gives form to the product (P:56). These three criteria help to understand design processes and their products. Jon Lang (2005) criticizes architects who think ‘anybody who can design a building well is capable of designing a good city’. As a result, architects have proposed, and in some cases, built cities (e.g. Radiant city by Le Curbusier, mega cities proposed by Norman Foster, and new towns such as Brasilia designed by Oscar Niemeyer).
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Figure 32 A Typology of Urban Design Projects (Lang, 2005)
To understand the drivers of change in the design process of public realms and changes in planning approaches, we need to evaluate the bigger picture of public space design in the theories of planning and policy making. Madanipour (2006) proposes a theoretical framework to define the role of urban design in the development control process and its future challenges. He argues that in order to appreciate the significance of urban design and its evolution, we need to recognize the main trends and changes that cities are experiencing (Carmona, 2010). Madanipour mentions globalization as a relatively new phenomenon (in the history of urbanization) which influences the economies of cities and consequently impacts their design and planning priorities. Although globalization is an example of the current trends and forces that are influencing cities, there are other issues such as climate change, which seems to be one of the major concerns in the current century (Thornley & Newman, 2011). Influences of the global economy have been studied from planning perspective. Manuel Castells (1988) proposed the “spaces of flow” theory to investigate how information technologies have revolutionized time and space in urban contexts. Space is a product of many variables including economy, culture, and history. Castells’ theory explains how
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market players and capitalism have changed their strategies producing new forms and places in different spatial scales.
Madanipour (2006) focuses on structural changes in economy, labor division, means of production etc. He argues that new trends in the economy have forced cities to compete with each other and this has changed the development market and consequently city centers. Madanipour (2006) concludes that “design is a helpful tool for development-friendly authorities that try to reduce the tensions between exchange value and use value, between development and conservation, between economy and society” (P: 183).
Urban space has been studied as a product of capitalism (or generally the dominant economic system) by new Marxists. David Harvey argues that urban space is shifting to become the consumption space rather than the production space (Harvey, 1991; Harvey, 1996; Harvey, 2007). Harvey argues that capitalism uses the postmodern culture to produce flexibility in use, investment, and space. As Lefebvre (1991) frames the concept of space in the critical discourse, modernist capitalism used space as a place for production while, since the mid-20th century, postmodern capitalism has produced space to gain the exchange value and uses space to promote consumption culture. Zukin (1995) believes that capital is intertwined with cultural systems of a city. In a capitalist planning system, there is a competition among cities to gain more exchange and use value through producing a high quality space that promotes the consumption culture. Consumption is the key component in the economy of cities. Food, art, shopping, and entertainment are different manifestations of the new culture and each demands its own space.
From a new Marxist perspective, urban space could be one of the productions of capitalism through market forces. According to Madanipour (2006), planning systems have been a medium through which these forces interact and shape the outcome. Local authorities are forced to behave similar to a corporation to maintain their revenues. There are two main forces influencing planning and development control systems. One is the market forces and the other one is social movements. Market forces tend to utilize planning system in favor of producing more profit or protecting and increasing exchange and use values. On the other side, social activism and public movements demand more democratic processes leading to sustainability and affordability. Most of current environmental regulations are the outcome of social campaigns protesting against social and environmental justice degradations (Haughton, 1999).
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We also can study the evolution of urban design practices in the context of planning theory changes. According to Fainstein and Campbell (2012) planning approaches changed from proposing long term comprehensive plans to providing a regulatory system. This pushes planning systems to focus on small projects rather than the whole city, which is titled incremental planning. These changes have made planning systems more plan-based, visionary, and more regulatory aiming to create higher qualities in public spaces (Madanipour, 2006). This change is more visible in the proposition of form-based codes and design guidelines studied by Elliot (2012), Punter (1999), Talen (2012), Lang (2005), and Ben-Joseph (2005).
Assuming that urban design guidelines and landscape regulations now are a dominant dimension of planning systems (Aherm, 2013), exploring this issue will lead us to ask: what kind of qualities are in the current agenda to be addressed either in projects or in design control standards? In addition, who defines what a good design is remains a key question. Madanipour (2006) claims that policy makers of cities, in the new global economy, have more emphasis on competing with other cities to attract more investment and more creative classes. A better quality of space can increase exchange values, attract more people and businesses (Gottdiener, 2010). Urban design should deal with some challenges for serving a better outcome. This approach fits with New Marxian theories of consumption space. Cities need a more vibrant space for shopping, dining and entertainment, which increases the exchange and use value of properties (Knox & Pinch, 2014). The city that provides a happier and more attractive place for residents and especially the creative class, can gain more investment and surplus.
The New Marxian theories, however, raise a conflict in their arguments. If capitalism as a dominant economic system encourages cities with higher qualities of open and public spaces, they are contributing to create a better place for all classes as well; all citizens can benefit from a walkable and bikable city with vibrant centers even if businesses benefit from too (Feagin, 1998). Making a city affordable never has been the ultimate goal of capitalism. This is the mission of planning authorities to advocate for vulnerable and low income groups through encouraging affordable housing development or providing other services. If the economic system and other forces encourage a specific space (production space or consumption space), planning theory and practice should identify these patterns and highlight the advantages, disadvantages, and impacts on other human and natural systems. If there are trends that harm nature or social justice or
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exacerbate climate change, planners need to regulate development to control those trends (Punter, 2010).
Recent design and planning paradigms encourage advocacy and environmental planning to protect the rights of social groups and the quality of natural systems. Graham and Aurigi (2007) believe that public spaces in cities have been occupied by privatizing and commodifying them. They advocate for social groups to have more extensive access in using and designing public and open spaces. Goheen (1998) also argues that the public sphere in cities should be democratized. Urban design movements since the 1980s have attempted to improve urban life in public spaces. Gaffikin et al (2010) investigated the roles of public spaces in ‘contested cities’. They propose a review of the historical and contemporary role of urban design in shaping social space and interrogate the feasibility of using urban design to facilitate more integrated cityscapes.
Jacobs and Appleyard (1987) in “Toward an Urban Design Manifesto” articulate that the goals of urban design are to achieve a better urban life or “an urban fabric for an urban life” including livability, identity and control, access to opportunity, community and public life, and an environment for all. Each of these goals can be studied from a different perspective. Here, I think we can connect the major concern of current planning and find the overlap with urban design, which is climate change. A public space should be designed with respect to the future challenges such as global warming to protect urban life in extreme events. Also, the design should be consistent with major climate properties. Urban design in Denver, CO should respect to the cold winters and hot summers while using the same form in Seattle would not make such differences in urban microclimates.
The quality of the built environment in public spaces is a key variable in improving urban life through promoting walkability and diversity of use. Therefore, built environments should have better aesthetic and social qualities (Rogers et al., 2011). The form and elements of spaces, also, influence climate conditions such as microclimate, shading, and thermal comfort (Watkins et al, 2007). Jan Gehl (1987) in his thorough study of pedestrian activity in public spaces, categorized outdoor activities as necessary, optional, and social activities. Optional and social activities are highly dependent on the quality of design. He doesn’t mention the climatic characters of cities and the way they can affect these activities, perhaps because twenty five years ago, global warming and climate responding design was not a major concern. However, Mahmood Tavassoli (2009)
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explored organic design of Iranian historical cities in the central part of the country with the hot and arid climate and found that public spaces are designed to mitigate high temperatures and create comfortable conditions in outdoor public spaces (Figure 33).
William Whyte paid attention to climatic elements in the design of public spaces and people’s behavior. He noted that in chilly days of winter, sunlight attracts people. He explains “what people seek are suntraps and the absence of winds.” He found the significant role of trees in public spaces. Trees are beneficial in winter because of blocking wind and in summer for the pleasant shade. He found that even on very cold days, small parks are quite habitable. He criticized the design of high rise buildings which create intense wind at ground level. He believed “Wind tunnel tests on models of new buildings are now customary, but they are not made with people in mind.” He mentions different cities such as Seattle and Chicago where high rise buildings damaged the public space by making them inhabitable and un-walkable. Whyte found the presence of trees incredibly useful for public spaces and argued that trees should be close to sitting spaces to provide aesthetic and microclimate benefits.
Figure 33 Yazd (Left) and Gonaabaad (Right) Climate Responding Organic Design in Iranian Cities (Tavassoli, 2002
P:19)
As I reviewed the literature of urban microclimate in the previous chapter, urban form and built environment characters influence urban microclimate. Thermal comfort creates a better place for all social groups including the elderly, children, and disabled people (Capeluto et al, 2003). Planning and design theories need to identify strategies to mitigate heat and embed them in policies and regulations. These activities also are related to climate change mitigation and adaptation. Reviewing the current design theories reveals that there is a clear trend toward climate responding design. However, there is still a gap between the literature and policies to implement heat
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mitigation strategies in practice through modifying built environments and form elements. In short, we need to reform design and planning theories leading to the practice to redefining a good design with respect to prospective climate challenges and to make cities more resilient.
Urban Renewal Policies
Climate change mitigation and adaptation strategies require some modifications in built environments to produce more energy efficient forms (indoor and outdoor) and to emit less GHG. Existing public spaces, urban fabrics, and buildings should be modified to meet the goals and objectives of climate change mitigation and adaptation policies. Modifying existing built environments will demand urban renewal efforts. Urban renewal projects could be a title for any intervention in physical environments with an intention to improve it (Roberts & Sykes, 1999). Therefore, urban renewal shares its historical evolution with planning history (Hall, 1996). In some literature, urban renewal approaches are categorized into pre-modern era, modern era, and postmodern era (Cooke, 1990; Gordon, 2003; Knox, 1987). In some literature, World War II was a benchmark in urban renewal policies because it caused a need for reconstruction of neighborhoods and providing social housing. In this section I classified urban renewal approaches into three categories: (1) the period of bulldozer and dictating top-down interventions intending to clean the built environment with emphasis on physical improvement, (2) the comprehensive approach to rehabilitate with focus on social rehabilitation, and (3) the economic development through revitalization of downtowns and developing catalyst sites.
In the first era, the goal of planning and intervention was obviating health issues through cleaning slums and low quality neighborhoods (Peterson, 1979). In European countries the redevelopment directed by Haussmann in Paris (1870) is a benchmark attempting to “treat overcrowded” neighborhood suffering from crime and disease through demolishing existing buildings, building wide streets and boulevards, sewer systems, and water ducts (Gandy, 1999). Carmon (1999) studied urban renovation in the US through clearance of land sites by public agencies and found that slum areas were demolished to construct shopping centers, offices, and conventional centers in the years after World War II. Carmon (1999) found that between 1949 and 1964 only less than one percent of federal funding for urban renewal was allocated to relocated households. These policies raised criticisms for neglecting social aspects of such extreme approaches. The challenges between Robert Moses and Jane Jacobs over renovation projects in New York city in
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the 1960s is a classic debate in urban planning considered as a benchmark for reviewing renovation policies (Gratz, 2011).
The second era is an outcome of social movements questioning consequences of totalitarian approaches to urban renovations. In the US after the 1960s many movements advocated civil rights and bottom-up processes in city planning to reduce poverty and empower low-income groups (Cullingworth, 1993). As a result, public opinion in planning processes became more important and demolishing a neighborhood to build a shopping center or office building was not possible anymore. In that time, many federal and local policies addressed poverty as a driver of blight in neighborhood. These programs aimed to decrease social injustice in cities. As Cullingworth (2009) mentions, President Johnson’s policies for “the great society” and the “war on poverty” were examples of federal policies. In addition, local governments and public agencies tried to take advantage of public participation in proposing and implementing plans. Cullingworth (2009) quotes from President Clinton (1995) that “the days of made-in-Washington solutions, dictated by a distant government, are gone. Instead solutions must be locally crafted...” (P: 295). Another important program aiming to empower communities was Community Development Block Grants (CDBG) signed by President Ford in 1974 for improving low- and moderate-income neighborhoods. All these approaches and policies led to stronger bottom-up or participatory community development plans (Cullingworth, 2009: 306).
I review economic development very briefly as the third generation of urban renewal policies. In a study by Gibson and Prathes (1977), social programs for supporting housing were examined to evaluate their efficiency in improving communities and the life of vulnerable people. According to this study, in most cases these programs were not effective. Storm (2008) identifies political coalitions between public agencies (city officials as representatives) and private corporations to invest significantly in renovating neighborhoods and downtowns. These projects also include catalyst projects that are targeted as development stimulation or capital attraction, which can improve the general economy of cities. In addition, there is more interest in preserving historical land marks and converting them to cultural attractions, hotels, and entertainment centers to market the city as a tourism destination.
Another recent trend in economic development strategies is related to the attraction of high tech startup firms and technology clusters (Yigitcanlar et al., 2008). These “knowledge-intensive
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industries” are dependent on creative class and entrepreneurs and can attract young generations of recently graduates into the labor force (Corey & Wilson, 2006). These startups are formed by students usually graduated from local universities and in most cases have strong relationships with faculties and research centers in fields such as software development, multimedia, robotic inventions, and biotech (Wu, 2005). Wu explores the reasons and factors that a city can attract these clusters and finds that first the presence of universities are a key factor in generating such groups and feeding them through cutting edge research; second, the relationship between universities and big industries that can provide funding for research projects plays a crucial role. However, there are still questions about the efficiency of this approach in helping vulnerable classes systematically (O’Mara, 2007). Improving the economy of the city through these clusters attracts many well-paid employees and consequently raises housing and service prices. Low-income classes barely benefit from this type of economic growth and eventually they will need to move to peripheral areas to find cheaper housing (McCann, 2007).
Different strategies of urban renovation approaches including economic development and physical reformations (renovation or reconstruction) are important because they are the only window for preparing our cities for future challenges. Street-height ratio, building materials, open spaces, landscaping opportunities, pocket parks, green/cool roofs, etc. are key variables for heat mitigation that require appreciation by urban policy makers.
Downtown development policies
Downtowns are becoming the heart of urban life again (Heath, 2001). This leads to several processes that gentrify city centers and attract investments, creative classes, and activities (Zukin, 1987; Wilson, 2004). Many cities are implementing urban renewal and design projects to create higher quality public spaces and more walkable environments (Isenberg, 2005). This provides new opportunities to modify urban form, improve spatial structures, and adopt climate change mitigation and adaptation policies (Yow, 2007). An urban design approach that incorporates urban microclimate strategies would create a more comfortable temperature for users of public spaces (Nikolopoulouetal., 2001). Besides improving social activities in public realms, there are energy and health concerns that heat mitigating policies could contribute to.
Birch (2009) studied downtown populations from 2000 to 2007 and found that the residential population living in downtowns rose 12 percent. He argues that the relationship between
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downtown growth and overall performance of the economy in cities is significant. He found that most cities in the West and South are growing while most declining cities are located in the North East and Middle West. He advocates that providing high density residential mixed use can contribute to the livability of cities in general. The new paradigm in downtown development is moving away from the heavily single use pattern of office development. The new paradigm encourages dense, walkable, mixed use with a considerable residential component providing small size housing. Public uses such as universities, hospitals and schools should be integrated with the fabric of downtown without disconnecting the walkable and commercial nodes. Birch shows that local governments tend to expand downtowns and dense mixed use districts.
Another dimension that city leaders have attempted to improve is public spaces and their amenities. In Birch’s study, many cities started heavy investment in redesigning downtowns to attract more users and increase property values. He provides the example of several cities that used gardens, parks, retail streets, etc. Birch argues that downtowns are more resilient against economic depression and during the last economic depression (since 2007) downtowns show higher growth compared to other areas (Birch, 2009; P: 151).
Storm (2008) explores two dimensions of change in downtowns including changes in the physical shape and changes in the economic and political forces impacting downtowns. Changes in the physical environment of downtowns are as an outcome of planning and design processes tending to encourage walkable and mixed use environments. Exploring the changes in political processes of downtown development has been discussed by political scientists and sociologists and is less addressed by planners. This discourse studies various stakeholders involved in the governance procedures, which includes elected officials and bureaucrats, corporate leaders and business associates, and neighborhood organizations or social groups. In the 50s and 60s downtowns were heavily influenced by corporations and business elites. Their decisions about moving their investments could impact the performance of business districts significantly. Availability of land in suburbs connected by highways could provide more financial benefits making corporations more resilient against property market collapses.
Strom (2008) studied the historical relationships between “business leaders” and “entrepreneurial mayors and development officials, leveraging federal urban renewal funds to shore up downtowns.” She believes although these relationships are contested by public groups,
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“economic elites” have still a considerable share in decision making of downtown reshaping processes. Strom questions to what extent the corporate power still matters in the interaction with other stakeholders. She concludes that in most major American cities, downtowns are not the heart of corporate power anymore. Land use of downtowns is a mix of cultural, entertainment, and retail, which means corporations own less land and have less interest in holding political power. Strom reviews approaches which encourage people to perceive downtowns as a place for leisure activities and entertainment including art galleries, walking places, sport venues, and retail to explore which political, economic, or social forces are stronger in shaping the built environment of downtowns.
Strom concludes (2008) that the economic base of ownership and land uses are changing from corporations, bankers, and manufacturers to city officials, real estate brokers, and maybe university presidents. She mentions that presence of non-profit and public officials has created a different development agenda compared to private entities and corporations in the past. This has resulted in the inclusion of public and non-profit officials in leadership boards of downtowns. However, it seems that in most cases, real estate partners stay as an effective player in downtown development processes. Strom’s argument is not proved in her paper and remains a hypothesis. She assumes that although real estate developers are a dominant player in decision making of downtown reshaping, their roles as investors are substantially different than corporations and bankers because their interests are different in the long term and short term. There is a gap in the literature exploring how changes of stakeholders of downtown investors and owners have influenced decision making processes in leadership boards and negotiations with city officials in designing PUDs, for example.
Some economists believe that downtowns could be strong attractions for tourism through providing cultural festivals, vibrant day and night life for diverse groups. From this point of view preservation of historical districts and buildings, development of museums, theme restaurants, and cultural events can promote the economy of downtowns and cities. In this approach, large districts of offices can degrade the quality of downtowns for tourism attraction (Xie, 2006). Kemperman and Borgers (2009) articulate how unique shopping opportunities with cultural themes can promote downtown tourism. They found that shopping supply, with strong accessibility supported by physical characteristics and preserved historical particularities are important aspects improving route choice behavior. In this study, they concluded that physical improvements could increase the economic performance of downtowns.
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Over the past twenty years, local economic growth played an important role in urban politics and planning in American cities. Local governments adopt increasingly entrepreneurial economic-development strategies to attract capital and start-ups. According to Leitner (1990) local governments behave entrepreneurially because of economic interests, or because autonomous political agents draw the attraction of entrepreneur industries. To identify these trends, it is necessary to analyze how economic and political processes, operating at different spatial scales, negotiate to influence policy making and local government actions. This is then helpful to explain the evolution of downtown development policies.
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Codes and standards
The identification of opportunities in the current policy frameworks for heat mitigation requires understanding the historical and political context of policies. Several policies and planning tools shape built environments. Each policy addresses specific aspects of built environments. For example, zoning regulates building envelopes, its location in parcels, and open spaces, uses etc. Subdivision codes regulate building-height ratios, street shapes and orientation and so on. All these parameters are important variables in influencing the microclimate of cities. In this chapter, first I review the general discussion related to codes and standards, their importance, contradictions, and complications. Then I review subdivision codes, zoning codes, and design guidelines.
Codes and standards are “the hidden language of place making” (Ben-Joseph, 2005). Planning and regulating standards share a long history. Marshal (2011) uses “urban code” to address and study all codes and standards including building codes, landscaping codes, subdivision standards, etc. I believe separating codes from planning practice in general could be misleading because in most cases codes have been the instrument of implementing the general plan, master plan, or comprehensive plan. In this section, I review the works and research of three authors who have explored codes (urban codes) specifically and their influence on urban form: Eran Ben-Joseph, Emily Talen, and Stephen Marshal. All of them review the history of urban codes and their emergence; nevertheless, they offer their own methods for embarking on this subject. My focus in this paper is not reviewing the history of codes and their evolution. Instead, I review how the codes produce built forms in recent planning practices to extract parameters that can impact urban microclimate.
Ben-Joseph (2005) provides a dialectic historical review exploring the contexts in which codes were offered and treated. He studies how these codes could cause problematic ambiguities, homogenization, and stereotyped developments. I will discuss his approach and findings later. Marshal (2011) reviews several international studies in different countries to show how codes evolved in their context and across nations. He concludes with categorizing these standards and offering some future directions. Talen (2012) picks a practical method through which she examines codes and standards by presenting examples on the ground to show how the existence or lack of codes can influence urban form.
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In his historical review, Ben-Joseph (2005) shows several examples of regulationsthat implemented standards and codes that were generalized and globalized. These standards were not designed to consider local specifications such as climate and culture. These standards generate similar buildings, shapes, and form. His points out that preparing codes respecting local particularities is an expensive and time-consuming process and many local governments borrow codes that already were prepared. He calls codes the hidden language of place making and probes the history to find evidence reflecting the existence of codes. American place-making code (language) has been replicated around the world. Ben-Joseph identifies two main variables in place-making which are traceable almost in all standards. The first variable is the concerns related to public health and sanitation. This variable has been a strong inspiration to regulate space and protect communities from disease and hazards such as fire. The second variable is related to the “desire for consistency” to facilitate preparing and implementing codes and construction of new neighborhoods.
Many codes and standards carry features and characteristics from their historical creations and modifications similar to genes. However, many of the drivers that contributed to the creation of such forms do not exist anymore. One of the examples that Ben-joseph (2005) points out is fire codes shaping buildings and subdivision layouts. He argues that these codes usually overestimated the risks to release agencies from any responsibility. Fire codes significantly impact urban microclimate. For example, street width, building heights, and roof/faqade materials can influence radiation absorption and reemission. Fire codes significantly restrict density and some shading strategies. Adopting fire codes has been considered a high priority in most communities and cities without evaluating and modifying them to address the local issues including climate parameters.
In addition, there is no considerable innovation in the design of fire fighter equipment to fit in narrower streets or taller buildings, even though the technology would allow us to provide smarter services. The improved methods of computer simulation to evaluate different parameters such as climate and energy issues, risk assessment, etc. can lead to better and more efficient standards. Ben-Joseph points out a controversial point that the emphasis on social and economic aspects of design after the era of modernism, has pushed the focus on physical design back and it is time to address physical aspects of design and planning to deliver a balance between social aspects and the physical environment.
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I think the peripheral role of technology and simulation for physical design and planning has not been significant until recent decades because the advances in computer applications were not profound enough to deal with some real complicated issues of the real world. In addition, adopting a set of prepared, documented, and examined standards, such as fire codes, is the result of legal complexities of dealing with possible harms. Local governments prefer to sacrifice improved planning in exchange for guarantying maximum safety. The decentralized governance system in the US is another reason because preparing such standards for local communities need a great deal of expertise and funding and fragmented governance system generating small local governments encourage them to adopt such national codes without worrying about legal consequences.
Marshal (2011) summarizes his cross-national review of codes and standards through categorizing them into three types based on their purposes. The first are codes with utilitarian purposes designed to provide health, sanitary, and safety such as fire related codes or even separation of industrial uses from residential areas. These codes protect properties against nuisance. The second category of codes serve a visionary approach. These codes aim to create a specific urban form and qualities through, for example, preserving historical fabrics and creating walkable neighborhoods. Design guidelines are an example of codes with such purposes to create or preserve some characters in downtowns and core urban areas. The third type of codes tend to create a better condition for different social groups especially for vulnerable groups. Provision of affordable housing and inclusionary approaches are examples of codes with such purposes.
Talen (2013) highlights the need for understanding the ways rules shape built environments and for exploring “the effects and the neglect of rules” (P: 2). She presents several examples that show how bad rules can neglect the consequences in built environments. Talen (2013) shows (Figure 34) that the municipal codes require a developer to provide one parking lot for every 250 square feet of commercial floor area. She argues that the outcome of this policy is very poor because of extensive parking lots and un-walkable spaces, which exist because of the absence of other rules to prevent extensive parking lots. She suggests some policy alternatives that could mitigate the vast parking areas including: parking maximum, limitation on size of surface parking lots, reduction of parking for mixed-use projects, walkways through parking lots, and required bicycle parking. Parking lots also play a considerable role in the microclimate of cities. Extensive impervious and dark surface of parking lots can increase radiation absorption and consequently
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can exacerbate urban heat islands. Therefore, some form elements such as large shopping malls surrounded by parking lots not only degrade walkability of cities but also they impact microclimate. However, the microclimate issue has not gained enough attention from planners and designers.
Figure 34 Shopping Mall in Chandler, Arizona, a product of neglecting the side effects of rides (Talen, 2013; P: 2)
Talen (ibid) identifies the right problem effectively and spots the right location to illustrate how poor policies create an unpleasant un-walkable space. I believe, however, her approach does not address the main problem. In other words, although the parking requirement policy forces such extensive parking spaces, the existence and location of such a large shopping mall, its relationship with streets and neighborhoods, offering single use with minimum landscaping qualities, and its segregation from the spatial structure of the city are also seriously questionable. Talen organizes her policy evaluation into three categories: use, pattern, and form. In each category she brings examples that regulations and rules have left a visible footprint on the ground.
All three authors introduce interesting methods for exploring the role of policies in shaping built environments. However, none of them offer a systematic method to identify the problem at
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different scales and hierarchies. For instance, they do not offer a method to identify poor outcomes of policies and finding the root of the problem from different perspectives including deficiencies in regional and city-scale policies (with respect to spatial structure of cities), zoning (or any sort of district regulation systems), use distribution policies, building envelope regulations, and landscaping standards. Any poor form is probably the outcome of a combination of all these deficiencies.
Also it would be helpful that such a policy evaluation method could categorize different aspects of a poor urban form implying issues such as (for example) walkability and bikeability, energy inefficiency, social exclusion, safety, and lack of identity issues. To frame a more precise policy evaluation method, I suggest a framework with at least two dimensions: (1) the subject of policy (related to form) such as land use regulations or building envelop control; and (2) type/scale of policy.
Subdivision regulations
The main goal of subdivision regulations is dividing large pieces of land into smaller ownership lots (parcels). In the Standard City Planning Enabling Act (1928) a subdivision is defined as a tool to divide land into lots or parcels for the immediate construction or future use and selling of land. Subdivision regulations are very important because they shape streets, blocks, lot sizes, and lot patterns. These parameters create the structure of built environments that hardly change over time. Also, these parameters play an important role in impacting urban microclimate. Lot size, street width, building location in a lot, building height limitations, front and backyards, vegetation refuges in streets all impact microclimate. The form produced by subdivision plans, as a structure for neighborhoods, changes very slowly and as a result it is very important to evaluate the consequences of subdivision plans in our environment and climate.
Cullingworth (2009) identifies variations in definitions of subdivision regulations in different states. The way terms such as “previously developed” and “improvement” are defined is one of the major differences. While zoning controls the development of individual parcels, subdivision regulations control the way a developer divides land and shapes a group of parcels, street alignments, grades, widths, drainage and sanitary facilities, location and size of easements and right of ways, fire roads, lot size and configuration, and other required facilities or uses for the neighborhood considering the size and scale of subdivision (Cullingworth, 2009). Although zoning
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DO PLANNING AND DESIGN POLICIES AND PROCEDURES MATTER IN MICROCLIMATE MANAGEMENT AND URBAN HEAT MITIGATION? By Mehdi Pourpeikari Heris B.S., University of Tehran, 2003 M.S., University of Tehran, 2006 MA., University of Sheffield, 2008 A dissertation submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Design and Planning Program 2018

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i Pourpeikari Heris, Mehdi Title: Do Planning and Design Policies a nd Procedures Matter in Microclimate Management And Urban Heat Mitigation? Dissertation Committee Chair: Austin Troy Dissertation Adviser : Brian Muller Dissertation Committee: 1) Ariane Midd el 2) Louise Chawla

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ii ABSTRACT In this research, I developed a method for analyzing how urban form affects urban microclimate and how planning and design policies shape urban form. I scrutinized the policies, contexts, and implementation procedures of urban r edevelopment projects in two cities in the Denver metropolitan area. Both the Belmar (located in Lakewood, Colorado) and 29th Street Mall (located in Boulder, Colorado) projects were conventional indoor malls developed in the 1960s, that declined in the 1990s, and were redeveloped in the early 2000s to create mixeduse walkable urban centers. The zoning approaches (Belmar used Form based code, 29th Street Mall used Euclidian), design guidelines, and local politics of these two projects were significantly di fferent in way s that resulted in different built environments after redevelopment. My research aim is to explore how these differences can potentially impact urban climate systems with positive or negative influences on climate variables such as wind, ambi ent temperature and mean radiant temperature. My research answers two research questions: (1) to what extent are different zoning approaches (Euclidian and Form based) capable of mitigating urban heat? (2) To what extent are planning contexts, including local politics, important in developing a climate responsive project? I found that a series of variables affected the process of planning and design in these sites. The findings show that the choices made in the development management affected the microclima te of both sites. The built form of Belmar is more effective in heat mitigation and creating a more comfortable temperature. Based on the results of both my microclimate simulations and the policy analysis , I identified five main themes in the development management of both sites that control microclimate outcomes and show why Belmar ultimately was a better project. These themes, which are also relevant for other environmental objectives, are : (1) urban vision, (2 ) land use and building form controls, ( 3) d esign guidelines, ( 4) public financing, and ( 5 ) condemnation/ownership factors . These five policy themes I have identified explain how a combination of context and choice variations affect the quality of built environments. Although many regulations did not intentionally address microclimate issues, elements that were considered for improving walkability contributed to heat mitigation as well. The simulation of policy and form variations showed that the built environment of Belmar has been more successful i n mitigating urban heat. Conflicts and a complex planning history in Boulder led to a very slow and ineffective review process that created a less climate responsive built environment.

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iii The findings of this dissertation show that the design strategies for improvement of urban microclimate are common strategies with creating a walkable city. In fact, the strategies that FBCs are offering for a good urban design, such as building frontage and landscaping standards, hand in hand with microclimate management. T hat being said, heat mitigation deserves to be one of the main principles of design and planning strategies. The more important question is how cities can manage development processes to achieve successful projects that address environmental and social val ues. Hoch ( 1996) argues that the pragmatic approach to defining the best planning choice can benefit from evaluation of successful projects or best practices to find the important factors. These lessons might be generalizable for other similar situations. The analysis of development management in relation to heat mitigation fits in this category. The themes I introduce in this paper show how planners can improve development management in relation to intended outcomes. Connecting findings to theory and the literature, conflict in a major project like Belmar or 29th Street Mall is inevitable. Conflict arises in agreeing on visions and goals by developers, cities , citizens, and owners. As Campbell ( 1996) demonstrated, reaching sustainability goals requires managing different types of conflicts such as property, resources, and development. He raised the question of “whether planners are likely to be leaders or followers in resol ving economic environmental conflicts.” He encourages planners to play a more active role in managing the conflicts rather than mediating the controversy as an outsider. The findings here shed light onto how planners can approach these conflicts and what s olutions or tools may be utilized to achieve the goals. What I found in these two projects was that in Belmar the city effectively managed the conflicts regarding financing of the project, ownership obstacles, and laying out the vision through new regulati ons. Whereas in Boulder, the conflict was not managed effectively and resulted in a long and controversial procedure that failed in addressing climate related issues. A big corporate mall developer may not have common values with planning staff in setting goals for environmental or social values. In such situations, I suggest using the five tools identified here to effectively reach the goals of good urban design (presented in the following Figure). Local politics, public participation, and local economics affect the development management procedures and ultimately have a strong control on project outcomes. The findings show that planners need to create an effective process but they also need to create strong visions, and improve regulatory tools such as zo ning and design guidelines before starting a major project.

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iv Five factors in the development management process that matter for microclimate management Urban Vision Land Use and Buildi ng Form Controls Design Guidelines Public Financing Ownership & Condemnation Development Management Microclimate Management

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v ACKNOWLEDGEMENTS I am very thankful for Brian Muller’s role as my adviser for these years of my P hD. He provided significant help as a mentor and as a friend. I also appreciate the profound help and support of Austin Troy. He provided intellectual support and funding that made this path possible. Ariane Middel helped me with providing technical suppor t on microclimate modeling. Louise Chawla, my other committee member, provided detailed help in developing my manuscript. Besides that, I am deeply grateful for the support that the College of Architecture and Planning at UC Denver and the Program in Envi ronmental Design at CU Boulder provided including scholarships, funding, and a warm home in which to thrive. I would like to especially acknowledge the invaluable and kind helps and supports that Alana Wilson offered. The friendship and mentorship of Shawhin Roudbari irreplaceable. I am also thankful for the helps and supports of MMB in a significant part of my higher education life. Lastly, I would like to offer my deepest gratitude to my family who tolerated the hardships I created for them by studying an d living abroad. They inspired and encouraged me with giving me unconditional love on this journey.

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vi TABLE OF CONTENTS I. CHAPTER 1: INTRODUCTION .................................................................................... 1 II. CHAPTER 2 LITERATURE REVIEW ....................................................................... 6 Climate Change and Urban Microclimate ........................................................................... 6 Climate change Issues ...................................................................................................... 7 Heat waves (as a disaster) .............................................................................................. 14 Adaptation and mitigation policies ................................................................................ 20 Vulne rability: ..................................................................................................................... 20 Urban Heat Islands ......................................................................................................... 29 The earth’s energy balance at urban scale ..................................................................... 38 Methods of measuring urban heat island ....................................................................... 41 Modeling and simulation of the urban microclimate ..................................................... 48 Scales of Climate Study ................................................................................................. 48 Formulation of Urban Energy Balance .......................................................................... 50 Urban energy balance components and urban geometry (form): ................................... 52 Urban heat island mitigation .......................................................................................... 62 Urban heat island mitigation in policy documents in Denver ........................................ 64 Conclusion of microclimate section ............................................................................... 66 A general literature review of planning and design codes and standards in urban development .............................................................................................................................. 69 Design theories ............................................................................................................... 69 Urban Renewal Policies ................................................................................................. 76 Downtown development policies ................................................................................... 78

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vii Codes and standards ....................................................................................................... 82 Subdivision regulations .................................................................................................. 86 Zoning ............................................................................................................................ 88 Political economy of zoning ........................................................................................ 101 Zoning: summary and criticism ................................................................................... 103 Design Guidelines ........................................................................................................ 105 Planning procedures ..................................................................................................... 108 Urban Heat Island Mitigation in Policy Documents .................................................... 108 Conclusion of planning and design policy section: ..................................................... 122 III. CHAPTER 3: METHODS ........................................................................................ 125 Research aim, objectives, and questions .......................................................................... 125 Research aim ................................................................................................................ 125 Research objectives ...................................................................................................... 125 Research questions ....................................................................................................... 126 Research Design .............................................................................................................. 127 Case studies ..................................................................................................................... 128 Belmar .......................................................................................................................... 128 29th Street Mall (Boulder, CO) ..................................................................................... 130 Component 1: Microclimate Simulation ......................................................................... 133 Data collection for the experimental phase: ................................................................. 133 Site models: .................................................................................................................. 137 Weather data: ............................................................................................................... 138 Soil Data: ...................................................................................................................... 141 Validation of simulated results: ................................................................................... 141 Urban microclimate simulations .................................................................................. 143

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viii Policy Scenarios ........................................................................................................... 143 Component 2: Policy Evaluation ..................................................................................... 147 Theory: ......................................................................................................................... 149 Data collection for the case study research: ................................................................. 149 Data analysis for policy evaluati on .............................................................................. 151 IV. CHAPTER FOUR: RESULTS ................................................................................. 154 Component one: Microclimate Simulation ...................................................................... 154 Simulation Results ....................................................................................................... 155 Scenario results ............................................................................................................ 160 Component two: Policy Analysis .................................................................................... 168 The story of two sites ................................................................................................... 168 Land use and building form controls: .......................................................................... 171 Land economy: ............................................................................................................. 175 Planning contexts: ........................................................................................................ 178 Planning vision: ............................................................................................................ 179 V. CHAPTER FIVE: CONCLUSION .......................................................................... 183 Final Take Aways ............................................................................................................ 187 REFERENCES .................................................................................................................... 190 APPENDIX A: INTERVIEW QUEST IONS ...................................................................... 201 APPENDIX B: ANALYSIS OF REGIONS AND SCENARIOS ...................................... 203

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ix LIST OF TABLES Table 1 Emissivity of Some Materials at 300 K (Cengel & Turner, 2004) .................................. 35 Table 2 Summary of Some Key Coefficient for Understanding Heat Transfer ........................... 37 Table 3 Common Urban Heat Island Observations and Hypotheses (Arnfield, 2003, P:23) ....... 43 Table 4 Thermal Bands of ASTER Satellite Images (Votano et al., 2004) .................................. 47 Table 5 Emissivity of Some Materials (Infrared Thermography Website, Retrieved December 2014 & Erell et al., 2011) ................................................................................................... 53 Table 6: Thermal Pr operties of Typical Objects and Materials in Urban Areas (Erell et al., 2011) ............................................................................................................................................ 60 Table 7 Average annual anthropogenic heat flux (E rell et al., 2011) ........................................... 61 Table 8: Proposed mitigation strategies, maximum potential temperature reduction, and possible energy savin gs (Memon et al., 2008) ................................................................................. 64 Table 9 : Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of Denver, 2014) ..................................................................................................................... 66 Table 10 Urban form eleme nts and microclimate modeling ........................................................ 67 Table 11: Numbers and Categories of Denver Zoning Districts from 1023 to 1994 (Elliot, 2008: P.12) ................................................................................................................................... 92 Table 12: Proposed mitigation strategies, maximum potential temperature reduction, and possible energy savings .................................................................................................................. 110 Table 13: Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of Denver, 2014) ................................................................................................................... 112 Table 14: Urban Heat Mitigation Policies Proposed in the Downtown Development Project (City of Phoenix, 2008) ............................................................................................................. 121 Table 15 Case studies .................................................................................................................. 132 Tab le 16 Technical specifications of LabJack TLH ................................................................... 134 Table 17 The initial values of the models ................................................................................... 141 Table 18 Interview codes and themes ......................................................................................... 152 Table 19 Summary of simulation results ( = effective in heat mitigation) ........................... 167

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x LIS T O F FIGURE S Figure 1: Atmospheric CO2 at Mauna Loa Observatory (NOAA, Retrieved in November 2014) . 7 Figure 2 Observed Change in Surface Temperature 19012012 (IPCC, 2013) .............................. 8 Figure 3: Multiple Complementary Indicators of a Changing Global Climate (IPCC WGI, 2013). ........................................................................................................................................... 10 Figure 4: The effect of changes in temperature distribution on extremes. Different changes in temperature distributions between present and future climate and their effects on extreme values of the distributions: (a) effects of a simple shift of the entire distribution toward a warmer climate; (b) effects of an increase in temperature variability with no shift in the mean (IPCC, 2012). (c) Effects of an altered shape of the distribution, in this example a change in asymmetry toward the hotter part of the distribution. ...................................... 12 Figure 5: US Billion dollar Weather and C limate Disaster time series from 1980 2011 indicates the number of annual events exceeding $1 billion in direct damages, at the time of the event and also adjusted to 2011 dollars using the Consumer Price Index (CPI) ........................ 13 Figure 6: Russia 2010 and US 2012 Heat Wave: temperature anomalies measured by satellites (NASA Earth Observatory, 2012) ..................................................................................... 15 Figure 7: Distribution of European Summer Temperatures since 1500 ( Barriopedro et al. 2011) ........................................................................................................................................... 16 Figure 8: Critical Points in HeatRelated Mortality Causalities (Kovats & Hajat, 2008) ............ 18 Figure 9: New Yorkers Crossing Brooklyn Bridge during the 2003 Power Outage (Stone, 2012) ........................................................................................................................................... 19 Fig ure 10: Annual Electric Grid Failures in the United States (Stone, 2012) .............................. 19 Figure 11 : The Relationships between Vulnerability, Exposure, and Climate Events in the Evaluation of Anthropogenic Risk Management (IPCC, 2014) ....................................... 21 Figure 12: Radiative forcing of climate between 1750 and 2011 (IPCC, 2013 WGI) ................. 24 Figure 13: Total U.S. Greenhouse Gas Emissions, 19902012 (EPA, 2014) ............................... 25 Figure 14: Total U.S. Greenhouse Gas Emissions by Economic Sector in 2012 ......................... 26 Figure 15 Conceptual Relationships between Climate Change Adaptation and Mitigation Plans and Public Health ressource McMichael, et al.(2006) ...................................................... 28 Figure 16 : Daytime and Nighttime Temperature Anomalies Resulting in Urban Heat Island (EPA, 2008) ................................................................................................................................. 30

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xi Figure 17: Heat Transfer through Conduction (engel & Turner, 2004) ..................................... 34 Figure 18 Convection Heat Transfer: hot air has low density and rises; cool air has high densit y and sinks (Cengel & Turner, 2004) ................................................................................... 34 Figure 19 The Absorption of Radiation Incident on an Opaque Surface of Absorptivity (Cengel & Turner , 2004) ................................................................................................................... 36 Figure 20: Incident Radiation May Be Reflected, Transmitted, or Absorbed (Pan, 2011) .......... 37 Figure 21 The Global Annual Meant Earht's Energy Budget for the Mar 2000 to May 2004 (Wm2) (Trenberth et al., 2009) .................................................................................................. 40 Figure 22 Contributions of Urban Landscape in Imbalance of the Earth's Energy Budget (EPA, 2008) ................................................................................................................................. 41 Figure 23 Observation of Luke Howard: the annual temperature curves (1797 to 1816) for the city (solid) and rural area (dashed) (Mills, 2008) .................................................................... 42 Figure 24 Portable Weather Stations That Log Temperature, Relative Humidity, Radiation, Precipitation (Rain), Wind Speed/Direction ..................................................................... 45 Figure 25 Atmospheric Layers above Urban Areas (Erell, 2011) ................................................ 49 Figure 26: Conceptual Framework of Urban Energy Balance for Microclimate Modeling (Erell et al., 2011) ........................................................................................................................... 51 Figure 27 Shortwave (Direct and Diffused) and Longwave Radiation (Erell et al., 2011) .......... 52 Figure 28 The Role of Street Ratio in Reflection of Solar Radiation (Erell et al., 2011) ............. 54 Figure 29 Sky View Factor Measurement Method (Erell et al., 2011) ......................................... 55 Figure 30 3D Sky View Factor Measurement Method (Erell et al., 2011) ................................... 55 Figure 31 Longwave Radiation Emitted from Surfaces .............................................................. 57 Figure 32 A Typology of Urban Design Projects (Lang, 2005) ................................................... 71 Figure 33 Yaz d (Left) and Gonaabaad (Right) Climate Responding Organic Design in Iranian Cities (Tavassoli, 2002 P:19) ............................................................................................ 75 Figure 34 Shopping Mall in Chandler, Arizona, a product of neglecting the side effects of rules (Talen, 2013; P: 2) ............................................................................................................ 85 Figure 35, Transect Zones: Rural to Urban Characters (FBCI, 2014) .......................................... 98 Figure 36 Proposed Building Massing (Phoenix, 2008) ............................................................. 119 Figure 37 Building Fron tage Regulations from the Design Guidelines of Downtown Belmar, Lakewood, CO ................................................................................................................ 122

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xii Figure 38 Dissertation conceptual model and components ........................................................ 128 Figure 39: Aerial Photo of Belmar before (left image, 1999) and after (right imag e 2014) (Captured from Google) ................................................................................................................... 130 Figure 40 Belmar Site Plan of the redevelopment project .......................................................... 130 Figure 41 Aerial Photo of 29th Street Mall before (left image, 2002) and after (right image 2014) (Captured from Google) .................................................................................................. 131 Figure 42 Temperature/Light/Humidity (TLH) Data Logger Produced by LabJack ................. 135 Figure 43: Tagged data loggers ready to be located in the field ................................................. 135 Figure 44 Location of data loggers in the site maps (red circles) ............................................... 136 Figure 45: Loction of data loggers .............................................................................................. 137 Figure 46 Temperature variations collected by a data logger in Belmar (sample p eriod: June 20th July 5th) ........................................................................................................................ 139 Figure 47 Light variations collected by a data logger in Belmar (sample period: June 20th July 5th) .................................................................................................................................. 140 Figure 48 Relative humidity variations collected by a data logger in Belmar (sample pe riod: June 20th July 5th) ................................................................................................................ 140 Figure 49 Site layouts for the existing condition scenario .......................................................... 144 Figure 50 Site layouts for the building scenario ......................................................................... 145 Figure 51 Site layouts for the street scenario .............................................................................. 145 Figure 52 Site layouts for the vegetation scenario ...................................................................... 146 Figure 53 Site layouts for the vegetation scenario ...................................................................... 147 Figure 54 Content analysis of interviews .................................................................................... 153 Figure 55 Distribution of Simulated A ir Temperature at 2 meters above ground at 3pm on June 29th 2015 for Belmar (left) and 29th Street Mall (right) .................................................. 156 Figure 56 Distribution of Wind Speed (meter/second) at 2 meters above ground at 3pm on June 29th 2015 for Belmar (left) and 29th Street Mall (right) .................................................. 156 Figure 57 Measurement regions and mean radiant temperature in Belmar (existing condition) 157 Figure 58 Measurement r egions and mean radiant temperature in 29th Street Mall in Boulder (existing condition) ......................................................................................................... 157 Figure 59 Simulated versus observed air temperature in the data logger number 3 location of Belmar ............................................................................................................................. 158

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xiii Figure 60 Simulated versus observed air temperature in the data logger number 4 location of Belmar ............................................................................................................................. 158 Figure 61 Simulated versus observed air temperature in the data logger number 2 location of Boulder ............................................................................................................................ 159 Figure 62 Simulated versus observe d air temperature in the data logger number 3 location of Boulder ............................................................................................................................ 159 Figure 63 Simulated air temperature of scenarios of Belmar in Lakewood ............................... 161 Figure 64 Simulated air temperature of scenarios in 29th Street Mall in Boulder ..................... 162 Figure 65 Comparison of microclimate variables across all scenarios where H values are hours of the day of simulation ....................................................................................................... 163 Figure 66 Comparison of Mean Radiant Temperature (MRT) for the building height scenario (shorter building height) and existing condition in region 7 of Bel mar ......................... 165 Figure 67 Comparison of wind speed and air temperature for the street pattern scenario (linear layout) and existing conditi on (grid layout) in region 9 of Belmar ................................ 166 Figure 68 Average housing value in Boulder and Lakewood (Zillow website, 2017) ............... 169 Figure 69 Boulder valley design guideline ................................................................................. 172 Figure 70 Design guideline of 29th Street Mall in Boulder ........................................................ 173 Figure 71 Design guideline of Belmar ........................................................................................ 174 Figure 72 The sit e plan that Civitas proposed in 2002 ............................................................... 182 Figure 73 Dissertation conceptual model and components ........................................................ 183 Figure 74 Five factors in the development management process that matter for microclimate management .................................................................................................................... 189

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1 I. CHAPTER 1: INTRODUCTION This dissertation aims to explore how urban development and urban form policies and their implementation processes can mitigate or exacerbate heat in cities. I compare two urban redevelopment projects in the Denver me tropolitan area: (a) Belmar project in Lakewood, CO and (b) 29th Street Mall project in Boulder, CO. To understand how form shapes urban microclimate, I simulated morphological factors including buildings, trees, and impervious/permeable surfaces, to gener ate microclimate variables (outcomes) such as air temperature, wind speed/direction, and mean radiant temperature. To explain how planning and design policies and procedures shaped urban form, and thereby the microclimate outcomes, I scrutinized the main planning and design policies of each site and their policy making and implementation procedures using qualitative methods. Anthropogenic changes to climate have already raised the average temperature of our planet by about 0.8 compared to its pre industri al levels. The Intergovernmental Panel on Climate Change (IPCC) (2013) has projected that the average temperature of our planet will increase by 4 6 by the end of this century. In addition, studies show that urban areas are warmer than their surroundings by 1 4 (depending on variations of general climatic and spatial situations) (EPA, 2008). Analyzing observed and simulated data shows that urban areas will be affected more intensely and frequently by extreme heat events, and in general by an increasingly warming climate (IPCC, 2013). The mortality and morbidity of people due to urban heat when intensified by heat waves are remarkable. The past two decades marked a record in the number of extreme hot days (heat waves) around the world (Coumou & Rahmstorf, 2012). Examples of such events include the European heat wave of 2003 (Stott et al. 2004), the Greek heat wave of 2007 (Founda and Giannaopoulos 2009), the Australian heat wave of 2009 (Karoly 2009), the Russian heat wave of 2010 (Barriopedro et al. 2011), the Texas heat wave of 2011 (NOAA, 2011; Rupp et al. 2012), and the U.S. heat wave of 2012 (NOAA, 2012; 2012b). The five hottest summers in Europe since 1500 all occurred after 2002, with 2003 and 2010 being exceptional outliers (Barriopedro et al. 2011). The number of mortalities attributed to the heat waves are shocking. According to Stone (2012) 70,000 people died in the heat wave of 2013 in Europe. Smenza et al (1996) identified 700 deaths related

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2 to the heat wave of 1995 in Chicago. The urban heat iss ue is also an environmental justice issue because it does not affect all social groups evenly. Harlan et al (2006) explored heat related health inequalities and found that lower income and minority groups are more likely to be exposed to higher temperatures. They argued that these groups also are more vulnerable as they have less capacity to cope with higher temperatures on summer days and nights. Higher temperatures can also affect energy and water usage in urban areas. Studies show that electricity use can increase by about 10% for every 1 increase in temperature (in the range of 35 ) (Akabri et al, 2005 and EPA, 2008). Studying the consequences of heat waves also shows that electricity grids might not have the capacity to meet high demands for power in e xtreme heat waves. This was experienced in the North East region when the heat wave of 2003 caused significant and extensive power outages (Stone, 2012). Power outage in an extreme heat wave can then expose vulnerable populations to significant risks. Wate r use can also increase with higher temperatures. Aggarwal (2012) found that water consumption in single family residential housing units in Phoenix, Arizona increased by about 3% for every 1 increase in outdoor temperature (in the rage of 37 ). The literature suggests that urban built environments can potentially increase or decrease ambient and mean radiant temperatures. Form elements such as building shapes and orientation, surface and ro of color, impervious surfaces, trees and vegetation quantity and distribution, and street form and directions are important for heat mitigation. As it is thoroughly discussed in the literature review chapter, urban microclimate is related to built environm ent configurations and elements. This means that different urban morphologies (as a general term for urb an form and configuration) could produce different microclimates (1one city). Considering all consequences of urban heat in relation to public health, energy and water consumption, and social life of public spaces, it is an essential subject in the design of cities to understand how policy variations and form variables change microclimates and potentially mitigate urban heat. Adopting a design approach to mitigate urban heat will make cities more resilient in the chang ing climate. Considering that primary design strategies for heat mitigation at the site scale concern building envelopes, trees, and landscaping qualities, this suggests that several policies and planning tools can be targeted to influence urban microclima tes. For example, zoning regulates

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3 building envelopes, location of building footprint within parcels, open spaces, and use. Subdivision codes regulate the ratio of building height to street width, street patterns and orientation, and so on. Fundamentally, codes and standards are “the hidden language of place making”, and various standards, such as building fire codes and design guidelines, have influenced building forms, street forms, and land subdivisions (Ben Joseph and Kiefer 2005) . Not only are codes and regulations important, but the cross effect of regulations also matters, as Talen (2013) highlights. For example, the combination of a poorly designed parking requirement regulation and poor landscaping standards may generate vast parking lots that exacerbate urban heat. Shaping and regulating urban form and landscaping with more details requires fine scale design policies that have received attention through form based codes. In th is dissertation, I will discuss how policies need to be designed specifically to address issues such as microclimate. Research on microclimate and urban morphology is particularly important at a time in which the urban form of U.S. cities is changing quickly (Estiri et al., 2014) and the urban core of many major metropolitan areas is becoming denser (Heris 2017) . Urban morphological change of this kind tends to last a long time, and the current demand for densification offers an opportunity to consi der how new morphologies can be optimized for climate related values. Although several U.S. cities have established heat related policies (e.g. Tucson, AZ & Chicago, IL), few have embedded heat regulations in tools such as zoning. My dissertation illumina tes a gap in both theory and the practice of planning and design in relation to prescribing fine scale policies and design strategies to address heat mitigation effectively. To translate heat mitigation strategies to planning practices, we need to build a scientific knowledge of heat mitigation solutions. In addition, planning theory needs to readdress the importance of fine scale regulations, such as form based zoning, in redevelopment projects. Furthermore, planning theory needs to connect environmental values such as microclimate to social and environmental justice discourses. Without understanding how environmental values are consistent or inconsistent with justice values, addressing conflicts in the planning procedure cannot be comprehensive. Planners need to have solid knowledge of climate related processes in parallel with justice issues to be able to mend the planning process for better outcomes. This dissertation connects the science of microclimate to urban planning and design policies and their implementation procedures. The findings of this research help planners to systematically embed form and landscaping regulations

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4 in common tools such as zoning and design guidelines to address heat mitigation. Furthermore, I shed light on the planning process versus outcomes to show how different choices in the implementation phase affect urban microclimate. Research Design: To address these gaps, this dissertation has two main and one subsidiary research questions: 1. To what extent do planning policies improve or degrade urban microclimate? Comparing form based codes and conventional zoning as two different approaches, which one can provide a better foundation for climate responding design and adopting heat mitigation strategies? 2. In what ways do planning procedures (discretionary processes) influence the implementation (built environment outcomes) of policies with respect to microclimate outcomes of redevelopment projects? To answer the research questions, I compare two urban redevelopment projects in the D enver metropolitan area: (a) Belmar project in Lakewood, CO and (b) 29th Street Mall project in Boulder, CO. Both the Belmar (located in Lakewood, Colorado) and 29th Street Mall (located in Boulder, Colorado) projects were conventional indoor malls developed in the 1960s, that declined in the 1990s, and were redeveloped in the early 2000s to create mixeduse walkable urban centers. Belmar uses a form based code and PUD whereas 29th Street Mall of Boulder uses a conventional zoning. Both sites share a simila r history and importance in their contexts and provide a unique opportunity to compare their policies and implementation procedures. I examine the different urban morphologies of these recently redeveloped urban centers in relation to their microclimates. There are several studies in which simulations of microclimate systems have been developed at a neighborhood scale for residential land uses. However, simulationbased research on microclimate systems and temperature effects has not been undertaken in urban centers and mixed use developments such as downtown areas in relation to design policies. I attempt to answer the fundamental question of whether the current planning and design policy frameworks contribute to heat mitigation or not. Answering this quest ion goes beyond the microclimate science because the overall impact of policies on other systems such as walkability needs to be addressed in the context of planning. Therefore, my dissertation bridges the science of microclimate to urban planning and

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5 desi gn policies. My main hypothesis is that some certain morphologies can mitigate urban heat through regulating radiation and wind circulation. Also, the existing policy frameworks matter in shaping urban form with such influences. This dissertation looks how morphology affects climate and how policy affects morphology. To explore these relationships, the dissertation is divided into two main components. The first component concerns urban microclimate simulations using an empirical research design. I used EN VI met to simulate urban microclimate variables based on the built form configurations of the two case study sites. This component explores the relationships between urban microclimate and urban form elements such as building height, tree density, permeabl e and impervious surfaces, etc. The simulation results are validated by temperature data loggers. The second component of the dissertation is built on the outcomes of the first one and uses a case study research design. Knowing how form elements affect mic roclimate, this component examines how microclimate outcomes at the sites are affected by planning choices and contexts. I examine the effects of regulatory systems including different types of zoning (form based vs conventional), planned unit developments (PUDs), and design guidelines, as well as context variables such as ownership and vision conflicts. The dissertation includes five chapters. After this introduction, in the second chapter I review the literature of climate change, urban heat islands, ur ban microclimate, and design and planning policies. The third chapter explains the research design, case studies, and analysis methods. Chapter four articulates the results and findings of the research including the outcomes of microclimate simulations and their validation results, policy analysis and interviews. Chapter five is the conclusion.

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6 II. CHAPTER 2 LITERATURE REVIEW Climate Change and Urban Microclimate All scientific studies about climate change and its drivers show that the earth will be in a g reat danger if humanity continues to influence E arth’s climate system s with the current pace. One of the most reliable resources in climate change studies are the reports published by IPCC 1 (Intergovernmental Panel on Climate Change) which has integrated m ost relevant studies . These reports ha ve informed scientific and political communities and promoted climate change research . In recent decades, changes in climate have impact ed natural and human systems. The evidence of climate change impact is strongest and most comprehensive and visible for natural systems. IPCC (2013) in the fifth assessment report (AR5) has warned that climate change is occurring and affecting the climate systems and weather patterns with a quicker pace tha n was expected . IPCC has proj ected that the average temperature of our planet will increase by 4 to 6 degrees Celsius by the end of this century. Several studies show that chance s of extreme weather occurrences, including heat waves, will be higher. Evidence shows that ecosystems and human systems are vulnerable to climate related extremes, such as heat waves, droughts, floods, a nd wildfires . The i mpact of such climate related extremes includes alteration of ecosystems, damage to infrastructure and settlements, consequences for mental health and human well being , morbidity , and mortality. In this paper, first, I review the literature of climate change, its related evidence, trends, and consequences. Following this section, I review the literature of extreme weather events and related a daptation and mitigation policies. The following section discusses urban heat waves and their 1 IPCC is a scientific intergovernmental body sponsored by the United Nations, which has been set up by the request of member governments. IPCC was first established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP), and later endorsed by the United Nations General Assembly through Resolution 43/53. IPCC was established to gather together the world leading climate change scientist to provide unbiased and valid research on the evidence and trends of climate change and its drivers. They publish periodic assessment reports reviewing the progress made on climate change science including adaptation and mitigation policies.

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7 impacts on public health. The final section is dedicated to the urban heat island effect , its drivers, science, and mitigation policies. Climate change Issues Ob served changes and trends It is proven by many studies that the main driver of global warming and climate change is an increase in the concentration of CO2 in the atmosphere , causing greenhouse effect . Measuring CO2 changes in the atmosphere was started by Charles D. Keeling who made systematic measurements of atmospheric CO2 emissions in 1958 at the Mauna Loa Observatory, Hawaii which is a remote place and therefore, is uninfluenced by regular pollutions (Keeling et al. 1976). Th e s e observations ha ve been continuing to today . Results (for the amount of CO2 in atmosphere) show ( Figure 1 ) an increase from 316 ppm (parts per million) in March 1958 to 395.93 ppm in November 2014 (N OAA, 2014 ) . Figure 1 : Atmosp heric CO2 at Mauna Loa Observatory (NOAA, Retrieved in November 2014) Recent studies estimate that the global average temperature is now 0.8C above preindustrial levels . This increase in temperature is t he globally averaged and combined land and ocean

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8 tem perature data as calculated by a linear trend and show s a warming of 0.85 (0.65 to 1.06C ) over the period 1880–2012 (IPCC, 2013) . Figure 2 shows the observed change in surface temperature since 1901. Independent studies using different resources found similar temperature increase on the land and in oceans. The re are natural factors that impact the global average temperature variations such as solar radiation fluctuations , volcanic events, and El Nino/Southern Osci llation . In the mentioned studies, these natural variations have been considered. IPCC (2013) in the last assessment report (AR5) argue that without the anthropogenic climate change, natural factors could even decrease the global average temperature. Fi gure 2 Observed Change in Surface Tempe rature 19012012 ( IPCC, 2013 ) Increases in the concentration of CO2 in the atmosphere have resulted in similar trend s in oceans. The dissolved CO2 in oceans has been increasing as well and has resulted in a significant change in the pH of water. This will make the water more acidic, which can impact on the ocean species specially corals. IPCC in AR4 (2012) and AR5 (2013) argues that it is very likely that the observed increase in global temper ature is due to increase in anthropogenic greenhouse gas concentration in the atmosphere (IPCC, 2013; IPCC, 2012). Several studies (i.e. Wigley & Santer, 2012; Santer et al., 1995; Stott et al., 2000) have explored natural factors that can influence temper ature such as solar

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9 variations, volcanic aerosol effects, and El Nino. The results show that over the last 50 years the summary of these variations would likely have contributed to cooling, not warming of global temperature. The increase of global temperat ure has resulted in significant loss of ice from Greenland and Antarctica. The IPCC AR5 reported 0.41 0.4 mm per year as the rate of sea level rise from the ice sheets for the period 1993–2003, while a more recent estimate by Church et al. in 2011 gives 1.3 0.4 mm per year for the period 2004–08. Measurements show that t he pace of ice mass loss has risen over the last two decades as estimated from a combination of satellite gravity measurements, satellite sensors, and mass balance methods (Velicogna 2009; Rignot et al. 2011). Figure 3 compares temperature anomalies of land surface, sea surface, and atmosphere. There is an evident trend in all temperature types presenting a significant increase. This trend also corr elates with sea ice extent loss and sea level rise (IPCC, 2013) . The scientific research and reports collected and presented by IPCC shows the depth climate change and its influence on natural and human systems. All evidence shows that the E arth’s climate is changing due to anthropogenic activities. Figure 3 summarize s the changes of some important weather parameters. In this figure, it is evident that there is a similar trend in these variables.

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10 Figure 3 : Multiple Complementary Indicators of a Changing G lobal Climate (IPCC WGI, 2013). Future global , regional , and local climate Projection models suggest that changes of climate systems significantly impact extreme weather events (Karl et al., 2008) . The increase of average global temperature by 4 6C can trigger many events including heavy precipitation, long droughts, heat waves or extreme hot days, and storms (IPCC, 2013) . For instance, in the recent decades most regions in North America ha ve been experiencing more unusually hot days and nights, fewer uncommonly cold days and nights, and fewer frost days. Heavy precipitation ha s happened with more frequency and intensity ( Handmer et al., 2012) . According to Karl et al., droughts are becom ing more severe in some regions. The

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11 intensity and frequency of Atlantic hurricanes have increased significantly in recent decades; however, there is not an observed significant trend in North America . Large fraction of anthropogenic climate change resul ting from CO2 emissions is irreversible on a multi century to millennial time scale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period (Cai et al., 2013) . Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic CO2 emissions (IPCC, 2013) . Due to the long time scales of heat transfer from the ocean surface to depth, ocean warming will continue for centuries. Depending on the scenar io, about 15 to 40% of emitted CO2 will remain in the atmosphere longer than 1,000 years. One of the most visible signs of global warming with direct influence on people’s lives is the rise of temperature. If the current trend in producing GHGs continue s , models project that the average annual temperature of our plane t will increase by at least 4C at the end of this century (Schellnhuber, Hare, & Serdeczny, 2012) . E ven considering the current commitments and pledges by governments would occur , there would about 20 percent likelihood of exceeding 4C by 2100 and a 10 percent chance of exceedin g 4C by the 2070s (IPCC, 2013) . Schellnhuber et al. (2012) argue that exceeding 6C increase in average temperature could expose human and other species to serious risks and probably to an end point. Anthropogenic climate change results in increases in th e frequency, severity, geographic extent, and duration of extreme weather events. Figure 4 shows how changes in climate systems can increase the frequency and intensity of extreme weather events. IPCC (2012) shows that there is a significant decreasing trend in the number of extreme cold days and nights while there is an increasing trend in the number of extreme warm days and nights at the global scale. There is sufficient historical data on land to support this arg ument confidently. Also, there have been statistically significant trends in the number of heat waves, floods, heavy precipitation events in regions and subregions. A warmer climate would increase the risk of floods (Hirabayashi et al., 2013). The occurr ence of exceptionally heavy rainfall events and associated flash floods in many areas has increased. Guhathakurta et al (2011) found that extreme rainfall and flood risk are increasing significantly in India except some parts of central India. IPCC (2013) also reported that besides some irregular patterns, the number of extreme precipitation events has been increasing globally.

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12 Figure 4 : The effect of changes in temperature distribution on extremes. Different changes in temperatu re distributions between present and future climate and their effects on extreme values of the distributions : (a) effects of a simple shift of the entire distribution toward a warmer climate; (b) effects of an increase in temperature variability with no shift in the mean (IPCC, 2012). (c) Effects of an altered shape of the distribution, in this example a change in asymmetry toward the hotter part of t he distribution. T he magnitude of disasters is not only related to the extreme weather. It also depends on t he vulnerability and resiliency of the communities. For example, economic recessions and wars can increase the vulnerability of settlements. The extent of vulnerability in a society is the outcome of some factors such as population dynamics and economic st atus as well as adaptation measures such as appropriate building codes, disaster preparedness, and water use efficiency. In the disaster risk management related to extreme weather events, three parameters ( Figure 11) should be con sidered: (1) severity of extreme weather events, (2) level of community exposure, and (3) vulnerability. Anthropogenic climate change can influence all the above parameters; therefore, climate change adaptation and mitigation policies need to address vulne rability, extreme weather events, and exposure.

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13 Figure 5 : US Billion dollar Weather and Climate Disaster time series from 1980 2011 indicates the number of annual events exceeding $1 billion in direct damages, at the time of the event and also adjusted to 2011 dollars using the Consumer Price Index (CPI) Models project considerable warming in temperature extremes by the end of the 21st century. IPCC (2012) claims that “it is virtually certain that increases in the frequency and magnitude of warm daily temperature extremes and decreases in cold extreme will occur in the 21st century at the global scale” (P:13) . IPCC suggests three scenarios for the amount of GHG emission till the end of the current century. The first scenario (A1B) which projects higher GHG concentration in the atmosphere predicts an increase in heat waves from 1 in 20 year hottest day to 1in 2 year event by the end of 21st century. Taking the third scenario into account (B1), heat waves will increase from 1 in 20 year to 1 in 5 year event. According to all three scenarios, it is very likely that the duration, frequency, and intensity of warm periods or heat waves will increase in most regions of the world. There are similar outcomes about other extreme weather events such as tropical cyclones, flood, droughts, heavy precipitation, etc. To summarize, in spite of clear eviden ce that human activity is driving climate change and extreme weather events , there are considerable uncertaint ies in predict ing future extreme events

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14 (IPCC, 2013) . Science of climate can project the average temperature not the timing and magnitude of the events ( Field, 2012) . On the other hand, the resiliency and adaptation capacity of the communities are dynamic qualities (Cutter et al., 2008) . All these dynamic variables make projecting the vulnerability of a community problematic. T he general recommendation of IPCC is enabling communities to be less vulnerable in extreme weathers through both adaptation and mitigation strategies. Figure 5 shows an increasing trend of climate and weather related disaster costs since 1980 in the US. Heat waves (as a disaster) In the previous sections , I articulated how both observations and projections suggest that climate change increases the frequency, intensity, and length of extreme heat events. The past decade marked a reco r d in the number of extreme hot days (heat waves) around the world (Coumou & Rahmstorf, 2012). Examples of such events include the European heat wa ve of 2003 (Stott et al. 2004), the Greek heat wave of 2007 (Founda and Giannaopoulos 2009), the Australian heat wave of 2009 (Karoly , 2009), the Russian heat wave of 2010 (Barriopedro et al. 2011), the Texas heat wave of 2011 (NOAA, 2011; Rupp et al. 2015), and the U.S. heat wave of 2012 (NOAA, 2012; 2012b). Figure 6 shows the surface temperature anomalies in the heat wave of 2010 in Russia and 2012 in the US. These heat events usually resulted in many heat related mortalities, wild fires, and agriculture crop losses (e.g. Coumou & Rahmstor, 2012). Heat wave is a relative concept varying in different locations. The temperature that can be assumed high in London could be a usual day in Phoenix. Heat events represent unusual (extreme) temperature for the average local temperature. These events were highly unusual with monthly and seasonal temperatures usually higher than three standard deviations (sigma) than the local average temperature. For that reason, these events are called threesigma events. Without anthropogenic climate change, such three sigma events would probably happen only once in several hundreds of years (Hansen et al. 2012). As it is presented in Figure 7 the fi ve hottest summers in Europe since 1500 all occurred after 2002, with 2003 and 2010 being exceptional outliers (Barriopedro et al. 2011). I n July 1995, the record setting heat wave in Chicago, at least 700 deaths were attributed to excessive heat exposure. Smenza et al (1996) used a very precise method to measure heat related mortalities from July 14 through July 17, 1995. They interviewed 339 relatives, neighbors, or

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15 friends of those who died. They found interesting information about the condition of peopl e impacted by heat and found that the risk of heat related death was increased for people with known medical problems who were confined to bed or who were unable to care for themselves. People who lived alone or lived on the top floor of a building were af fected more intensely. The study shows that having social contacts such as group activities or friends in the area was protective. In other words, people with weak social support with medical illness were at great risk. Figure 6 : Russia 2010 and US 2012 Heat Wave: temperature anomalies measured by satellites (NASA Earth Observatory, 2012)

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16 Figure 7 : Distribution of European Summer Temperatures since 1500 (Barriopedro et al. 2011) The number of people died because of the 2003 heat wave is estimated about 70,000 (Field et al. 2012), with daily excess mortality reaching up to 2,200 in France (Fouillet et al. 2006). This heat wave that set a record of 7C higher than average temperature s is considered the single most catastrophic weather event in Europe since weather observations have been recorded. Barriopedro et al (2011) claims that the magnitude of this event attracted attention to heat waves as a silent killer. Seven years later, t he heat wave in Russi a in 2010 caused about 55,000 deaths (Barriopedro et al. 2011). In 2012, the Americans , experienced a sever heat wave and drought period ( NOAA 2012, 2012b). In the same year, the United States had several wildfires, marking a new record in terms of impacte d areas ( 7.72 million acres ) (NOAA 2012b). 1.

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17 Body mechanism for dealing with heat Long exposure to high temperatures can lead to “ heat related illnesses, including heat cramps, heat syncope, heat exhaustion, heat stroke, and death.” Heat exhaustion is the most common issue leading to heat stroke which is a “ severe illness clinical ly defined as core body temper ature 40.6C (105F), accompanied by hot, dry skin and central nervous system abnormalities, such as delirium, convulsions, or coma .” (Luber & McGeehin, 2008; P:429) . The elderly and people with chronic medical conditions (e.g., cardiovascular disease, obesity, neurologic or psychiatric disease) are at high risk. As Luber & McGeehin ( 2008) point out, estimation and measurement of heat related mortality is challenging because illnesses such as heat exhaustion and stroke are not consi dered as serious problem s requiring reporting to national health agencies by hospitals as heat related crises. Also heat related health problems cause other conditions (e.g. heart failure in people with chronic heart illnesses). T he criteria used to attrib ute heat related death s vary among states and countries. According to Luber and McGeehin ( 2008) medical examin ers attribute heat exposure as a primary or contributing caus e of death only if they record a core body temperature of above 40.6C (105F) . Besides mortality, significant numbers of morbidity have been recorded in heat waves. For example, according to Semenza et al. ( 1996) over 1000 excess hospitalizations were recorded as heat related in Chicago 1995. High temperature increases the pressure in the human body through loading more intense work to heart and other organs. As temperature rises, blood circulation should be faste r to deliver water required for perspiration effectively and also to mitigate the excessive core temperature. As long as the lost water is constantly replaced, the body would be able to maintain the core temperature through perspiration. However, the heart would be increasingly under pressure to circulate fluids at an elevated rate. Sweating also will contribute to sodium loss, which increases the stress in other organs. The lack of water will make blood thicker and consequently will raise the risk of clott ing which can lead to heart attack or stroke. The lack of sodium will cause muscle cramp and spasm and dysfunction of internal organs. Stone ( 2009 ) states that human body can tolerate the exposure to excessive heat for about 48 hours before suffering heat related symptoms. The duration of warm days is one of the most important variables that can influence high risk populations. However, heat expos ur e is not the only variable . P eople who do not have social

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18 support to act appropriately or people who ha ve chro nic illnesses will be victims of heat waves. Figure 8 shows factors that play an important role at each phase (Kovats & Hajat, 2008) . Figure 8 : Critical Points in HeatRelated Mortality Causalities (Kovats & Hajat, 2008) Heat stress influences people’s behavior. Wyon et al (1996) found that heat stress negatively affects the vigilance of drivers. They compared the behavior of drivers in 21C and 27C in responding to signals. Their research showed that at 27 C drivers missed the signals 50% more than the same situation in 21C . Also, the response time was longer. Stone ( 2009) notes that the heat intensity could be much higher inside the vehicles. In the 2003 heat wave the temperature inside the cabins of a tram could reach to 48C (120F). Many studies (e.g. Grandjean & Grandjean 2007) show that heat stress decreases the efficiency and cognitive capacity of people in doing their daily activities. Heat wa ve and stress on urban infrastructure Heat waves also increase the stress on urban infrastructure. A long heat exposure increases the demand for air conditioning use which consequently increases the demand for electricity. In a normal summer day about one third of electricity use in domestic buildings is related to air conditioning systems (Lam, 2000) . Excessive heat can increase this number significantly . The raised demand of electrical power can result in failure of power generation and transition as well . Power plants could also stop because of excessive load. Stone ( 2009) notes that in the 2003 heat wave, in some cases, the temperature of some nuclear power plants approached the thresholds that would have required an immediate shutdown. On August 14, 2003 the United States experienced one of the most massive power outage s in American history. A high load to the electrical grid caused failure of distribution system in some

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19 Mid western and Northeastern states. According to Stone ( 2009) 55 million residents of MidWestern and Northeastern cities experienc ed an extensive power outage. The black out in Manhattan, New York was visible and significant because of high population density and high rise buildings. New York subway could not function and streets were blocked by traffic jams. Population had no way to leave Manhattan except walking away. Figure 9 shows New Yorkers that were trying to leave Manhattan in the absence of public transportation. Figure 10 illu strates that the number of electrical grid failures is increasing. Figure 9 : New Yorkers Crossing Brooklyn Bridge during the 2003 Power Outage (Stone, 2012) Figure 10: Annual Electric Grid Failures in t he United States (Stone, 2012)

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20 The lack of power can cause several other problems such as having access to public transportation, water, telecommunication, and other infrastructures dependent on electricity. For example, delivery of water requires pumps t o deliver in higher elevations such as skyscrapers. Without power, many buildings and offices will not have access to water. Another unexpected consequence of the 2003 heat wave in Europe was the closure of rail systems and roadways (Stone, 2012) . Railways particularly are susceptible in extreme heat waves because the thermal expansion of rails increases the risk of derailing trains. According to Stone ( 2012) in the 2003 heat wave a freight train derailed near London. Similar to rails, the surface of roads and the structure of bridges may be affected in extreme heat waves . In a very hot day, some airplanes are not able to take off because of thin air at the ground level. Studies show that warm days can reach to an extreme heat event severity, exacerbated by urban heat island effect. Tan et al (2010) found more extreme heat events in urban areas compared to exurban neighborhoods in Shanghai, China. They found that urban heat island effect can potentially increase the duration of heat periods and consequently i ncrease heat related mortalities. There are at least three trends that suggest heat waves could cause significant mortalities in the future. The first trend is the general global warming that has been discussed in the previous section. IPCC projects that this increase could be about 4C by the current mid century. The second trend is aging population in the major large cities mostly because of increasing life expectancy. The elderly populations are in greater risk compared to others. The third trend is growing urbanization which can potentially exacerbate urban heat island effect s . These three effects together increase the risk of mortality and requires targeted adaptation and mitigation strategies. Adaptation and mitigation policies Vulnerability: All stud ies and evidence show that human communities and natural ecosystems will be exposed to a greater risk (magnitude and frequency) of extreme weather events. One of IPCC’s (2014) working groups (WGII) overlays the climate change facts and projects on human se ttlements to measure the global risks. This group studies how risk patterns are shifting due to climate change. In their recent report (WGII AR5) the adaptation and mitigation opportunities and requirements are articulated. This report focuses on risk and advances the approaches for improving planning processes in all scales. Figure 11 (IPCC, 2014) shows how anthropogenic climate change increases hazards and consequently increases risk. Socioeconomic

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21 processes and adaptation/mitigation efforts could also influence risks and vulnerability. This cycle is the core of adaptation and mitigation guidelines. Uneven development and injustice usually increase vulnerability in lower income groups. Figure 11: The Relationships between Vulnerability, Exposure, and Climate Events in the Evaluation of Anthropogenic Risk Management (IPCC, 2014) Vulnerability is a function of the extent to which a community is exposed to risks and also the extent of their adaptive capacity (Davoudi et al. , 2009). The exposure depends on the magnitude of risks caused by climate change. For example, the magnitude of high temperature in a heat wave is important in the risk assessment process. The sensitivity refers to the pre paredness of a community in confronting risks. Vulnerability is an estimation of risk for people, infrastructure, and economic sectors. The vulnerability level varies between places and between population groups, depending on the way extreme conditions aff ect people (Davoudi et al., 2012) . For example, flood affects certain places and population groups living in flood plains, while heat waves affect certain age groups, people with health conditions, or people without appropriate air conditioning systems. Children, the elderly, and people with health conditions are usually considered more vulnerable in extreme conditions. They are not as mobile as other groups; they are more likely to not be able to operate machines and other safety systems; and finally , thei r body is more susceptible to health risks (Kelly & Adger2000) .

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22 In the vulnerability measurement the ability (capacity) of social groups to cope in an extreme condition should be evaluated. In most cases, low income groups are less prepared to confront adv erse effects of climate change. They also are susceptible in post disaster situations. For example, recovery is more difficult for low income groups due to access to a proper insurance or social network. According to the IPCC, climate change mitigation policies refer to interventions that revers e anthropogenic climate change drivers such as greenhouse gas emission or land cover change. Climate change adaptation is the action of adjusting natural and human systems to be less vulnerable in extreme weather con ditions and their expected direct or indirect effects. In other words, adaptation strategies enable human communities to enhance their resiliency in extreme weather condition (IPCC, 2014) . Climate change mitigation policies usually a re long term strategies to slow down the pace of climate change drivers , w hile adaptation policies address short term strategies to cope with adverse effects. Adaptation and mitigation policies are necessary along with sustainable development and therefore, all planning hierarchies (from national to local scale) need to address them as their core objectives. Adaptation and mitigation policies should be pursued in a parallel way (simultaneously) . Swart and Raes (2007 ) argue that these strategies do not conflict and t herefore, they need to complement each other at different time scales. Planning authorities and institutions should follow these policies together in an integrated framework. Planners not only need to define appropriate policies for adaptation and mitigation, they also need to articulate the relationships between adaptation and mitigation strategies, including conflicts, consistencies, priorities, time scale, and responsible institutions. Howard (2012) believes there is a lack of systematic approaches in the p lanning literature to frame the relationships between mitigation and adaptation policies. In most of planning literature, these two are being studied separately. He identifies cases in which adaptation policies are not consistent with mitigation strategies. For examp le, for being prepared for heat waves, air conditioning systems could be a solution while they could increase GHG emission. Sometimes, planners need to trade off conscious ly when they choose one strategy with some adverse side effects. Howard argues that planners should have a comprehensive understanding about the climate change science and the impacts of their decisions for both mitigation and adaptation. Howard (ibid) argues that global

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23 mitigation is impossible without local mitigation; furthermore, witho ut effective global mitigation, local adaptation would be impossible. Howard (2012) introduces some principles for planners dealing with adaptation and mitigation policies. The first principle informs the overall priority of mitigation over priority. Of co urse, there are situations in which short term adaptation solutions are required to be resilient a gainst an extreme situation. However, the changing climate is the greater risk and the projections show that the human race and other species are in significant danger. Therefore, the first priority for planning in a changing climate is mitigation and the most important mitigation objective is reducing GHG emission. The second principle suggests that mitigation is the main form of adaptation. Therefore, communi ties should remain committed to behave and consume responsibly and be environmentally conscious. Planning for mitigation policies need a thorough understanding of climate change drivers. Although CO2 concentration in the atmosphere is the main driver, the re are other variables that play important roles. All variables that influence the Earth’s energy balance can potentially be addressed in the mitigation policies. The Earth’s energy budget will be discussed in the following section. In short, any variable that increases the radiation absorption should be in the list of climate change drivers. Figure 12 : Radiative forcing of climate between 1750 and 2011 (IPCC, 2013 WGI) shows the share of each driver in the global warming process. The chart shows that greenhouse gases have the highest share in trapping more energy. Nevertheless, the IPCC’s chart does not explain the indirect effects of these drivers. For example, the albedo effects that resulted from land use change have contributed to less solar radiative forcing. Radiative forcing is the net incoming energy from the sun, typically expressed in watts per meter squared. However, land use change results in several indirect influences on climate systems. For example, a concrete surface may have higher albedo value (more reflective) compared to vegetated surface but it changes the storm water flow, humidity, surface heat, etc. Overall, the IPCC provides prec ise measures about atmospheric drivers but it does not provide precise measures a bout land use change and their consequences.

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24 Figure 12: Radiative forcing of climate between 1750 and 2011 (IPCC, 2013 WGI) Although land cover change may not directly influence the radiation and energy balance, it is usually the sign of settlement development, deforestation, etc. Urban development, settlement expansion, and sprawl affect energy consumption, GHG emission, water resources, and natural ecosystems. There is a strong stream in the planning literature, exploring how ur ban form and spatial structure of cities can impact VMT (Vehicle Miles Traveled). Studies such as Bertaud ( 2004) and Clark (2013) found that sprawled cities and metropolitan areas emit more GHG and higher densities can reduce emission per capita. Mitigation efforts need to be integrated through all scales from international to local. In order to address the right issues, we need to identify the importa nt drivers that can be controlled at the urban scale planning level. According to t he United States Environmental Protection Agency (EPA), GHG emission depends various variables such as fuel price, winter and summer conditions, and economic situation. EPA’ s data show a little decline in GHG emission, which they attributed to the shift from coal electricity generation to natural gas and hydropower ( Figure 13 ) .

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25 Figure 13: Total U.S. Greenhouse Gas Emissions, 1990-2012 (EPA, 2014) The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation. According to EPA (2014), electricity production is the main GHG emission resource. Figure 14 shows the share of each sector in emitting GHG. According to this figure, there is a significant emission produced by transportation and residential/commercial sectors. Local governments and planning aut horities can substantially mitigate emission in these sectors. Also, EPA (ibid) argues that land use and f orestry offset approximately 15% of 2012 greenhouse gas emissions . Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of gre enhouse gas emissions. In the United States, since 1990, managed forests and other lands have absorbed more CO2 from the atmosphere than they emit.

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26 Figure 14: Total U.S. Greenhouse Gas Emissions by Economic Sector in 2012 The IPC C, EPA, Post Carbon Institute, and many other important research groups all argue that mitigation policies should be pursued at local levels with an integration with national or global efforts. As Lerch (2007) argues municipalities must adapt effective pol icies to mitigate climate change drivers. Lerch focuses on energy consumption and believes municipalities can benefit from mitigation strategies in short and long term. For example, they can pursu e building codes that are in favor of efficient energy consu mption. Compact city form, public transit infrastructure, walkable and bikeable cities, energy efficient buildings, renewable energy development, and land use and open space protection policies are some examples that mostly municipalities are responsible f or. The science of climate change is well studied. However, as Davoodi et al . (20 09) argue, it seems t hat there is less studies exploring how planning policies should address climate change adaptation and mitigation . Nevertheless, a sustainable planning pa radigm could be seen as a direction to mitigate climate change trends. For example, urban infill strategies responding to urban sprawl have been tended to reduce VMT (Vehicle Mileage Traveled) and emission. According to Davoodi et al . ( 2009) planning theor y should provide an integrated firm framework

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27 to direct the practice of planning more effectively. The available literature about planning adaptation and mitigation is disparate and does not provide a coherent image. T he pace of climate change is fast; our cities will encounter serious extreme weather events in the close future. This substantially changes the context of planning and requires a new pr ior itization of policies and aims. In other words, planning as a practice itself should be resilient to embr ace climate change adaptation and mitigation actions more quickly . Figure 15 shows the conceptual framework indicating the relationships between mitigation and adaptation strategies and the health effect issues of climate change. Climate change is changing the horizon of cities ’ future. Therefore, planners should make cities ready to confront this situation and more importantly, move toward mitigating current anthropogenic changes.

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28 Figure 15 Conceptua l Relationships between Climate Change Adaptation and Mitigation Plans and Public Health ressource McMichael, et al. (2006)

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29 Urban Heat Island s The u rban heat Island phenomenon (science) Urban areas defined as heat island s are believed to be about one to four degrees Celsius warmer than their surrounding s because of built environment intensity (Corburn, 2009 and EPA, 2008) . However, this is a controversial quantification because different studies used very diverse methods to measure urban heat island effe ct s and they offer different values. The variability of findings are due to disparate definitions of urban and rural area, surface and air temperature, day and night time temperature, and averaging timelines (summer, annual, monthly, number of warm days or nights, etc.). These differences in measuring heat island effects will be discussed in the later sections. Urban heat island effects are visible and notable during the warm summer days. Urban h eat island s impact communities by increasing energy consumption, air conditioning costs, air pollution , GHG emissions, heat related morbidity and mortality, and water demand . Urban built environments contain more buildings and impervious surfaces compared to rural or natural environments which are covered by vegetati on or soil (that can keep moist ure in) . As urban areas develop, the landscape s change. We add more mass to the ground such as buildings, roads, and other infrastructure replac ing open land and vegetation. Permeable surfaces which are capable of keep ing moi st ure in them become impermeable (concrete and asphalt) and dry , which loads more thermal mass on the surface. These changes tend to generate higher surface temperature and store/trap the energy. As a result, urban areas become warmer than their surroundin gs; this is called urban heat island (EPA, 2008). The temperature anomaly is measurable through surface and ambient (atmosphere) temperature. On a summer day, surfaces with less moisture or low albedo (such as asphalt) absorb more radiation resulting in he ating up the surface. In a natural environment vegetated area absorb less temperature because of water presences. However, bare soil also may have a high surface temperature depending on its moisture level. In a summer day, the impermeable surfaces exposed to direct sunlight can heat up to 50C while the temperature of shaded or moist surfaces would be close to air temperatures (Memon, Leung, & Chunho, 2008) . Temperature anomalies attributed to urban heat islands have different behavior in day and night. During the day, it really depends on the land cover type of the natural environment in the

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30 surrounding areas. Vegetated land cover or moist soil would create a cooler area compared to urban areas. B uildings, masses, and urban surfaces with their relatively higher thermal mass absorb and store energy during the daytime. At night, they emit long wave radiation and release energy into the atmosphere, resulting in higher urban temperatur es as compared to surrounding areas (Akbari, 2005) . According to EPA (2008) t he annual average atmosphere “ temperature of a city with 1 million people or more can be 1.8–5.4F (1–3C) warmer than its surroundings. On a clear, calm night, however, the temperature difference can be as much as 22F (12C) ” (EPA, 2008, P.1) . Figure 16 shows daytime and nighttime temperature anomalies attributed to urb an heat island s . Figure 16: Daytime and Nighttime Temperature Anomalies Resulting in Urban Heat Island (EPA, 2008) Urban heat island consequences An u rban heat island is an i mbalance in the climate system; therefore, it creates other consequences in natural and human systems. In this section, I briefly mention the literature available regarding urban heat island consequences. Urban heat and public health:

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31 In the public health literature, the effect of heat is usually reviewed as an issue of heat waves. Heat waves can be exacerbated by urban heat island s . However, it is important to differentiate these two phenomena. I reviewed the impact of heat waves in the previous sections. Urban heat and energy consumption Urban heat island effects increase energy and water consumption significantly. Santamouris et al. (2001) found that an intense urban heat island effect in Athens, Greece can increase the energy consumption of buildings . In cases where summer time cooling load on the electricity system could be doubled. They also found that in winter, urban heat island effects reduce the heating demand by 30%. Akbari et al (2001) found that electricity demand i n cities increases by two to four percent (2 4%) They measured that the urban heat island effect in Los Angeles is about 0.5they estimated that the electricity demand increases by 5 10% for cooling buildings to compensate the urban heat island effect. They concluded “mitigation of urban heat islands can potentially reduce national energy use in air conditioning by 20% and save over $10B per year in energy use and improvement in urban air quality” (P:295). EPA (2008) also provides a similar energy consumption rate for compensat ing the urban heat island effect. Their estimation is that f or every 1F increase in temperature, the peak urban electric demand increases 1.5 to 2%. This is the same amount if we conv ert it to Celsius (in the range of 9596F or 3535.5C) . Another problem appears when energy consumption overloads the electricity system in heat waves. Steadily increasing temperatures may result in power outages ( Figure 10 ) . As discussed before, this could cause s erious harm to vulnerable groups. Urban heat and water consumption The relationships between water consumption and urban heat is not well stablished. I could find only one peer reviewed paper on this. Aggarwal (2012) a rgue d that the analysis of longitudinal data using a mesoscale atmospheric model, shows that the variations in surface temperature affected water consumption in single family residential housing units in Phoenix, Arizona. They argue that each one degree Fa consumption by 1.4%. They found that this variation correlates with lot size and pool size of housing units.

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32 Urban heat island and air quality Urban heat islands impact air quality locally and regio nally. R egional air quality could be affected by the increase in energy consumption and electricity demand if the main resource for electri city is fossil fuels. L ocal air quality would be impacted because of ground level ozone intensity. When the temperate is higher, the intensity of ozone will be higher at ground levels. EPA (2008) argue d that elevated air temperatures increase the ozone formation. When other variables related to ozone formation (“such as the level of precursor emissions or wind speed and direction”) are controlled ’NOx and volatile organic compounds (VOCs) react in the presence of sunlight’ (P: 14). In an empirical study, Stone (2005) explored 50 largest American metropolitan areas and found that “annual violations of the national ozone st andard were more strongly associated with regional temperatures than with the emissions of regulated ozone precursors from mobile and stationary sources ” (P: 13). Urban heat island and environmental injustice Urban heat does not affect all social groups ev enly . Harlan et al (2006) explored heat related health inequalities. They used microclimate simulation to find out the temperature variations in several neighborhoods. This model estimated the outdoor human thermal comfort index for eight neighborhoods. The result of this study shows t hat the lower income and minority groups are more likely to be exposed to higher temperatures. They argued that these groups also are more vulnerable as they have less capacity to cope with higher temperatures on summer days a nd nights. They conclude that “u rban heat island reduction policies should specifically target vulnerable residential areas and take into account equitable distribution and preserva tion of environmental resources” (P: 2847). Kovats and Hajat (2008) also addressed urban heat as an environmental and occupational hazard. They argue that lower income and minority groups cannot afford implementing heat mitigating solutions such as vegetation, increasing roof albedo, etc. Furthermore, these groups do not have access to efficient air conditioning systems, insulated and well designed housing. Accumulation of all these variables make them vulnerable in extreme heat events. Findings of Semenza et al (1996) about the characteristics of affected population during the July 1995 heat wave in Chicago proves that heat as a hazard affects low income and minorities more intensely.

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33 The science of energy balance To understand how urban heat islands form we need to have a solid understanding of physics of heat transfer and the E arth’s energy balance. We need to understand how surfaces and materials absorb energy and transfer heat. In this section, first, I briefly explain the fundamentals of heat absorption and transfer. Second, in the following section, I will review the methods of urban heat island measurement and exploration, their benefits, and disadvantages. Fundamentals of heat transfer: What is heat? This is a fundamental question in the science of urban heat island and microclimate . G eneral ly, most definitions of heat refe r to a relative temperature difference. We may compare one object with another object and the one with higher temperature would be considered as the hot object. From another perspective, we may define a base temperature as a benchmark and anything above that temperature could be considered as a heated substance. Heat is a type of energy which is related to the energy of molecules in a substance. Heat transfers because of energy differences . Each system tends to reach the thermal equilibrium. Therefore, ener gy with the shape of heat transfers from the hot substance to the cold substance until they reach the same temperature. Using rules of thermodynamics, we can measure the rate and quantity of heat transfer. Therefore, the engine of heat transfer is temperature difference. Heat transfers in three ways: conduction, convection, and radiation. Conduction is the physical interaction of two substances through the neighbor particles ( molecules ). For example, a hot coffee cup in a room cools down through the inter action of surface particles with air particles. The rate of het conduction through a medium depends on the temperature difference, the shape or the geometry of the medium, its material, and its thickness. For example, buildings loos energy through the conduction of walls and roofs. Figure 17 shows how heat transfers through conduction. Materials have a property named “thermal conductivity” which defines their abilities in heat conduction. Materials with higher thermal conductivity transfer heat more efficient ly . Another important property of a material related to measuring heat transfer is “heat Capacity”. Heat capacity defines how much energy a material can store per unit volume. For example, t his explains how much heat one cubic m eter of wood can store compared to one cubic meter of asphalt.

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34 Figure 17: Heat Transfer through Conduction ( engel & Turner, 2004 ) Convection is the mode of heat transfer between a solid surface and the adjacent fluid (liquid or gas). Fluids that can move faster, can transfer heat faster. If a fluid is exposed to higher temperature in one side, its molecules get energy through surface conduction then they start to move due to pressure differences. In other words, c onvection is t he process of heat transfer from one location to the next by the movement of fluids. The moving particles of the fluid move energy. The fluid flows from a high temperature location to a low temperature location. In urban areas, convection is one of the imp ortant ways through which surface temperature heats the air above it. Then the heated air moves around and increase s the ambient temperature ( engel & Turner , 2004). Figure 18 shows the convection process. Figure 18 Convection Heat Transfer: hot air has low density and rises; cool air has high density and sinks (Cengel & Turner , 20 04) The third way of heat transfer is radiation. Radiation is the electromagnetic wave that transfer s energy through emitting photons (energy) from matter as a result of the changes in the electronic

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35 configurations of the atoms or molecules. Radiation does not need any substance as a medium to transfer the energy. Heat transfer through radiation is the fastest (with the speed of light) type of energy transfer because photons carry the energy through space. Atmospheric particles can block or attenuate photons . Any object with the temperature higher than zero Kelvin radiates energy in the form of electromagnetic waves. The energy tr ansfer rate through radiation is a function of the Kelvin temperature (T) raised to the fourth power (Cengel & Turner, 2004) . The rate of heat transfer through radiation depends on the material of objects. The maximum amount of radiation that an object can emit can be calculated through Stefan Boltzmann law E = A (T)4 in which: E is the total emittance (emitted radiation from a surface) is the Stefan Boltzmann constant (5.67 * 108 W/m2K4) A is surface area T is temperature (Kelvin) is emissivity of the surface Emissivity is a property of materials and explains how efficient that material is in emitting energy. Emissivity is a value between zero and one ( 0 1). An ideal surface that radiates at maximum rate is called a blackbody . The emissivity of blackbody is one ( =1). The emissivity of all materials in t he real word is less than one. Table 1 shows the emissivity of some sample materials at 300 Kelvin. Table 1 Emissivity of Some Materials at 300 K (Cengel & Turner , 20 04 ) Material Emissivity Aluminum f oil 0.07 Anodized aluminum 0.82 Polished copper 0.03 Polished gold 0.03 Polished silver 0.02 Polished stainless steel 0.17 Black paint 0.98 White paint 0.9 White paper 0.92– 0.97 Asphalt pavement 0.85– 0.93 Red brick 0.93 – 0.96 Human ski n 0.95 Wood 0.82 – 0.92

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36 Soil 0.93 – 0.96 Water 0.96 Vegetation 0.92 – 0.96 Another important property of material s is the fraction of the radiation energy incident on a surface that is absorbed. Em issivity explains how well a surface radiates (emits) energy, while absorptivity explains how well a surface absorbs energy . A blackbody object is also a According to Cengel & Turner (2004) , the absorptivity and emissivity are a function of temperature and radiation wavelength. Kirchhoff’s law states that the absorptivity ) of a surface at a given temperature and wavelength are equal. Figure 19 shows how an incident radiation can be absorbed or reflected. Figure 19 The Absorption of Radiation Incident on an Opaque Surface of Absorptivity (Cengel & Turner , 2004) How does incident radiation interact with a surface? Three things may occur when incident radiation reaches a surface. The radiation (energy) can be absorbed, transmit, or reflected ( Figure 20 ) . According Cengel & Turner (2004), the sum of these three variables are one: Reflection + Transmittance + Absorption = 1

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37 Figure 20: Incident Radiation May Be Reflected, Transmitted, or Absorbed (Pan, 2011) radiation is always longer than the incident radiation because the temperature of the receiving surface is lower than the temperature of sender surface. This is because hotter objects emit at lower wavelength. For example, the maximum energy of radiation emitted by su n at the top of atmosphere is about 0.4 m (short wave radiation) while an object with the temperature of 300 Kelvin (26C) is about 10 m (long wave or infrared radiation). Reflection is different with re emittance. Figure 20 sh ows reflection not re emittance, which is part of the incident radiation and therefore its wavelength is close to the main incident radiation. In order to measure the ability of reflectivity of a surface we use Albedo measurement. Albedo is also is a coef ficient which is a value between zero and one. Albedo describes the percentage of reflected amount of an incident radiation . Albedo is a function of material, its surface color, and its roughness. For example albedo of a perfect mirror is one meaning that it reflects 100 percent of the incident radiation. According to Kirchhoff’s law, surfaces with high reflectivity (or roughly albedo) have low emissivity. These fundamentals are important for understanding the urban heat island phenomenon because cities ab sorb and store more heat mostly through radiation (receiving from the Sun). Table 2 s ummarizes the terms and coefficients we need for explain ing the process of absorbing, storing, and re emitting heat. Table 2 Summary of Some Key Coefficient for Understanding Heat Transfer Coefficient Symbol Description Heat Conductivity C Explains how well a material can conduct heat Heat Capacity HC Explains how a material can store heat per unit volume (is a measure of the amount of energy required to raise the temperature of a given volume of a material by a given number of degrees . Emissivity Explains how well a material can emit energy (is a function of temperature and wavelength) Absorptivity Explains how well a material can absorb radiation (also is a function of

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38 Albedo (Reflectivity) A Explains ho w well a surface can reflect an incident radiation (high albedo surfaces reflect the short wave radiation coming from the Sun in the form of short wave) The earth ’s energy balance at urban scale Climate change research started with observing the evidence of change in the late 19th century. Explaining the drivers of climate change needs a strong quantitative modeling f ounded on physics of energy flow in the Earth’s atmosphere and on its surface. According to Stevens and Schwarts (2012), Arrhenius took the first steps in formulating the effect of carbon dioxide in the surface temperature in 1896. Although his model was still insufficient and did not consider some key issues. The research in this field has grown rapidly in recent decades. Understanding the energy flow in a system like the Earth involves numerous variables, interactions and processes that are all tied together. Study of the Earth’s energy balance or budget is the corner stone of explaining climate change processes and identifying its drivers pr ecisely. Later efforts in the 1960s resolved some complicated issues of radiative heat transfer, especially in long waves (infrared) energy transmittance (Stevens & Schwarts, 2012) . The u rban heat island effect is one of the anthropogenic climate change i ssues. This phenomenon is the result of changing the Earth’s landscape. These interventions on landscape, not only contribute to the global climate change but also impact regional climate s which potentially exacerbates extreme heat events. The resource of energy and heat on the Earth is radiation coming from the Sun. It is important for understanding the urban heat island issue to understand how radiation coming from the Sun interacts with objects and surfaces and to identify the variables that can potentia lly contribute to more heat absorption and restoration. First, I explain the global Earth’s energy budget . T hen I will discuss how urban landscape influences the energy flow. Fundamentally, any mitigation action that we choose to take has to be consistent with the energy flow. Anthropogenic interventions on the Earth’s atmosphere and surface have changed the energy flow and made it imbalanced. It is clear that GHGs are the main global warming driver; however, there are other areas such as land cover that pr ovide opportunities for climate change mitigation along with urban heat island mitigation.

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39 Figure 21 is a conceptual framework for explaining the energy fluxes reaching to the Earth, being absorbed, reflected, and emitted out. Th e estimated numbers have been updated in several studies. One of the main studies carried out by Kiehl & Trenberth ( 1997) . The estimations have been improved due to progress in observations and evidence collected by satellite data which provides global cov erage. As Figure 21 shows, the incoming solar radiation at the top of atmosphere is 341.3 Wm2 (Watt per square meter). The radiation coming from the Sun is mostly centered in short wave and visible spectrum (0.30.5 m). The Eart h’s atmosphere plays a very critical role. It reflects 79 Wm2 of the incoming radiation back to the space. The atmosphere, also, absorbs 78 Wm2 of the incoming solar energy, which warms up our atmosphere. After reaching the radiation to the surface, 23 W m2 of it will be reflected and 161 Wm2 of it will be absorbed. Totally, 102 Wm2 (79+23) of radiation is reflected back to the space in the form of short wave radiation. The other 70 percent (239 Wm2) of incoming short wave radiation is absorbed either by atmosphere or surface , which is the resource of heat and energy of our planet. When the Earth’s atmosphere and its surface are warmed up, they start to emit radiation in the form of long wave radiation (infrared). The heated surface of the Earth, on a verage, emits 396 Wm2 in the form of long wave radiation to the sky. From this amount 40 Wm2 passes the atmosphere and goes to the outer space. The remaining 356 Wm2 will be absorbed by the atmosphere. The warmed up atmosphere then emits long wave radiation to all directions. From one side it emits 199 Wm2 radiation to the outer space. On the other direction, atmosphere emits long wave radiation back to the surface. This is where GHGs cause global warming because they absorb more short wave and long wave radiation; also, they emit back this energy to the surface; in other words, they trap energy in the lower atmosphere. According to IPCC AR5 (2013) the energy imbalance , on average, is about 0.6 Wm2 (0.21). Trenberth et al (2009) estimated the imbalance as 0.9 Wm2. This imbalance is the amount of energy that drives the global warming and climate change at the global scale.

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40 Figure 21 The Global Annual Meant Earht's Energy Budget for the Mar 2000 to May 2004 (Wm2) (Trenberth e t al., 2009) Energy budget in urban areas After reviewing the science of heat transfer and energy budget, we can explain what properties in urban areas can create an imbalance energy flow and result in urban heat island. As I discussed before, the differen ce of urban and rural areas is the landscape. In urban areas , we change the surface with materials that have a series of different properties in terms of heat transfer behavior. For example, urban areas have significant area covered by asphalt such as road s, roofs, and parking lots . Asphalt has a high emissivity value meaning that it absorbs radiation more effectively and emits it back more intensely (at long wave range); also, asphalt has low albedo value which means it reflects less short wave radiation b ack to the sky. On top of these, we add more mass to the environment, accumulated in a relatively small area, increasing the heat capacity or thermal mass. In other words, we are creating a large pool that has capacity of storing a great amount of heat ver y efficiently. Further more, an urban landscape creates a rough surface (porous) that can trap radiation between buildings . Also urban landscape increases the surface area and as a result more air interacts with warm surface. This contributes to the sensibl e heat which is heat transfer through conduction at the surface. Another variable in urban areas is anthropogenic heat produced by cars,

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41 industries, and air conditioning systems. These machines and facilities release a significant amount of heat to the urban area. In later sections, all these variables will be formulated for urban microclimate simulation. Urban landscape can trap short and long wave radiation between buildings and canyons. Figure 22 is the conceptual framework pres enting the interaction of radiation with masses, sensible heat, anthropogenic heat, and latent heat . Figure 22 Contributions of Urban Landscape in Imbalance of the Earth's Energy Budget (EPA, 2008) Methods of measuring urban heat island In this section, I review the common and prevalent methods of urban heat measurement. I draw their advantages and disadvantages and approaches in formulating heat. It is widely believed that urban heat influences local and regional climate, changes local wind regimes, impacts cloud forming, impacts humidity distribution, and alters precipitation patterns. Many studies introduce Luke Howard (1772–1864) as the pioneer researcher identifying the impact of urban areas on local climate. He explored the climate of London (1802 1830) and published three volumes of a book titled “The Climate of London”. Identifying the urban heat island effect was based on his own collected data and temperature records of three different sites outside London. Figure 23 shows the outcome of Howard’s measurement. A lthough Howard’s observations implicate urban heat

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42 island, the condition of temperature instruments and their general local morphologies are unknown (Mills, 2008) . Figure 23 Observation of Luke Howard: the annual temperature curves (1797 to 1816) for the city (solid) and rural area (dashed) (Mills, 2008) One of the technical and conceptual issue s of measuring or simulating urban heat is the scale issue. Urban heat is land is a meteorological issue which is the outcome of several variables with scales ranged from building scale to mesoscale. For example, the material and albedo of building roofs, parking lots, and roads need high resolution data and measurement while me soscale variables are affected by the general climate in the region such as horizontal and vertical air movements including Coriolis force, which can forcefully replace the air above a region and replace it with a different pressure and temperature. As Arn field (2003) points out, the definition of scale in conceptualizing urban heat island determines how we should quantify heat transfer between surface and atmosphere. Most theoretical and conceptual models for observing or simulating urban heat do not inte grate mesoscale and microclimate scale. Scale issue is conceptually resolved for energy flux integration and exchange (Arnfield, 2003) . Later, in the review of climate modeling section, I will explain Urban Canopy Layer (UCL) and Urban Boundary Layer (UBL) . A vailable models are not able to integrate the simulation of urban heat from building scale to mesoscale. Studies such as Chen et al (2011) are examples that tried to link mesoscale models such as WRF to urban scale meteorological studies. In the next subsection, I categorize the approaches used to study urban heat island s and discuss the advantages or the complications that could lead to flawed conclusions . Observing heat island variables

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43 Many studies are built on the observation of temperature variati ons in urban and rural areas. Most of these studies correlate observed temperature variations with the location or spatial configurations. Arnfield (2003) summarizes these observations and hypotheses in Table 3. Table 3 Common Urban Heat Island Observations and Hypotheses (Arnfield, 2003, P:23) Empirical generalization Reference UHI intensity decreases with increasing wind speed Ackerman (1985); Park (1986); Travis et al. (1987); Kidder and Essenwanger (19 95); Eliasson (1996b); Ripley et al. (1996); Figuerola and Mazzeo (1998); Magee et al. (1999); Morris et al. (2001); Unger et al. (2001) UHI intensity decreases with increasing cloud cover Ackerman (1985); Travis et al. (1987); Kidder and Essenwanger (1995); Eliasson (1996b); Ripley et al.(1996); Figuerola and Mazzeo (1998); Magee et al. (1999); Morris et al. (2001); Unger et al. (2001) UHI intensity is greatest during anticyclonic conditions Unwin (1980); Unger (1996); Shahgedanova et al. (1997); Tumanov et al. (1999); Morris and immonds (2000) UHI intensity is best developed in the summer or warm half of the year Urban heat island is a function of many variables at different scales ranged from mesoscale to building scale. In many studies the systematic complication s of urban heat are ignored and t he phenomenon is studied using limited factors which resulte d in flawed arguments and conclusions. For example, some studies show that the intensity of urban heat is not the greatest at night times in all cases (Mirzaei & Haghighat, 2010) . It could vary based on regional air flows, humidity of the region, soil type , vegetation coverage, etc. For example, Repley et al (1996) found that the intensity of urban heat is more significant in daytime compared to nighttime. The contradictory results are usually due to Observation of urban heat (air temperature vs. surface t emperature) There are two common temperature measurement methods prevalent in urban heat studies: air (atmospheric) temperature and surface temperature. Although spatial pattern s of surface temperature correlate with air temperature, they do not match comp letely. Th e s e differences are

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44 due to different behavior of these two phenomena . Surface temperature is highly depende nt on radiation expos ure and surface materials. As a result, its spatial pattern ha s strong variations with sharp edges. On the other hand, air temperature is less correlated with landscape variation and geometry. Instead, air temperature highly depends on air flows and turbulence at different atmospheric layers due to convection and advection forces. U rban canopy layer (the lowest level clos e to surface) is more affected by the surface temperature than higher layers through convection heat transfer. This correlation is higher in a calm weather. Observing air temperature: Urban heat island phenomenon was first identified by observing air temp eratures in urban areas compared to rural areas. The first temperature records documented for urban heat w ere collected by Luke Howard in the 1810s 1820s (Mills, 2008). Studies that used ambient temperature distributed a series of thermometers throughout a region to record the variations in urban and nonurban areas. Three types of equipment may be used in this approach. (1) Formal weather stations maintained by meteorological organizations (such as NOAA in the US), (2) portable weather stations that can re cord multiple parameters, and (3) simple thermometers and data loggers. Each of the above methods has advantages and disadvantages. Formal weather stations collect precise data in highly controlled conditions. The provided information by weather organizat ions are highly reliable. They also provide historical data which makes longitudinal studies possible. However, the fact is that these stati ons are not systematically distributed to capture urban and rural temp erat ure differences. In urban areas, there are limited stations, which are not located in preferable locations to explore urban heat island phenomenon. For example, Gedzelman et al (2003) used 50 National Weather Service (NWS) stations to measure urban heat island effect in the New York metro area. An other example is the study of Peterson and Owen (2005) in which they used the ambient temperature data collected by national weather stations. Many studies have used a type of portable weather station that can be installed in a specific location. These instruments are capable of collecting multiple parameters such as temperature, relative humidity, wind speed and direction, and light or radiation intensity. The quality of these instruments ranges from armature ones to very professional and precise equipment. Figure 24 s hows two model weather station s which are capable of logging temperature, relative hum idity and wind speed/direction. In many urban heat related studies, researchers have installed their own

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45 stations in predefined locations. In the recent decade, some volunteers has installed and shared the information of these weather stations publicly . The data provided by these network is not as reliable as national or formal stations because there are different types of instrument s but could still benefit studies with a better distribution for large metro areas. WunderMap2 website is an example of such a network. Examples of studies that used portable weather data loggers are Tso (1996), Unger et al (2001), and Giridharan et al (20 04) . Figure 24 Portable Weather Stations That Log Temperature, Relative Humidity, Radiation, Precipitation (Rain), Wind Speed/Direction Observation of urban heat (surface temperature): Using advanced spectrometers and sensors pr ovides significant advantages in measuring land surface temperature (LST) through thermal remote sensing methods. Considering that thermal sensors can be mounted on satellites or airplanes, measuring LST is feasible for extensive regions. On a hot day with a clear sunny sky and calm weather, the sun radiation (shortwave radiation) reaches to the surface of the earth and depending on the albedo and emissivity of the materials can heat up significantly. In urban areas, impervious surfaces such as roads, roofs , and walls can be 50 to 90F (27 to 50C) hotter than the air, whereas moist or shaded surfaces do not receive the direct shortwave radiation and as a result remain nea r ambient temperatures (EPA, 2008). As surface temperature is highly dependent on direc t shortwave radiation, studies measure day and night LST to understand the behavior of LST. According to EPA (2008), the average difference in daytime 2 http://www.wunderground.com/wundermap/

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46 LST varies in the range of 18 to 27F (10 to 15C) in urban and rural areas. However, the difference in nighttime LST is generally less , ranging between 9 (5C) to 18F ( 10C). Thermal (infrared) sensors detect longwave infrared ranges of the spectrum (9m 13m). The maximum radiation of objects with approximately 0C 80C temperature occurs in this range. Th e receiving radiation from an object is the function of its temperature, emissivity, and wavelength. When emissivity and wavelength are known, we can calculate the temperature of the object. Many studies have used satellite thermal infrared images to detect LST. Imhoff et al (2010) studied the relationships between impervious surfaces and their intensity with LST. They used MODIS satellite images to capture LST. MODIS provide relatively low resolution images (1km by x 1km) for studying urban heat island. H owever, Imhoff et al (2010) compared several metro regions to explore how urban development might cause higher LSTs. They considered a wide range of variables such as topography and NDVI (Normalized Vegetation Index), land cover (extracted from Landsat TM images), and population data. They found that ecological contexts such as vegetation and land cover type has a significant influence on the magnitude of daytime urban heat island effect during the summers. They concluded that the presence and intensity of impervious surfaces are the main driver of urban heat islands . Stone (2001) used a high resolution thermal image (10m x 10m) collected by NASA for the Atlanta metro area. This image is captured by thermal sensors mounted on an airplane. Stone used this hig h resolution resource for calculating parcel energy flux (generated by surface temperature). He concluded that low density residential development produces more heat compared to high density ones. Landsat satellites are one of the popular resources to calculate surface temperatures. Landsat Thematic Mapper (TM) has one thermal band (band 6: 10.40 m 12.50 m) has 120m by 120m resolution; “ but products processed before February 25, 2010 are resampled to 60meter pixels. Products processed after February 25, 2010 are resampled to 30meter pixels ” (USGS Landsat Mission Website3, retrieved on January 15th 2015) . Landsat Enhanced Thematic Mapper Plus (ETM+) also provides one thermal band (band 6: 10.40 m 12.50 m) with 60m by 60m resolution; “ Products processed after February 25, 2010 are resampled to 30meter pixels ” (USGS 3 http://landsat.usgs.gov/band_designations_landsat_satellites.php

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47 Landsat Mission Website4, retrieved on January 15th 2015). Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) are the most recent satellite launched in 2013. It provide s two thermal band (band 10: 10.60 m 11.19 m and band 11: 11.50 m 12.51 m); “ TIRS bands are acquired at 100 meter resolution, but are resampled to 30 meter in delivered data product ” (ibid). For example, Zhou et al (2011) used Landsat ETM+ to capture LST. They studied the influence of composition and configuration of land cover types on LST. They concluded that the composition of land cover types could be more influential in the magnitude of LST compared to land cover configuration. They found that buildings could produce the highest LSTs. Unsurprisingly, vegetated land cover types produce less land surface heat. There are many studies that used a similar methodology for measuring LST in relation to urban heat island using Landsat images. For example, Singh & Grover (2014) used Landsat ETM+, Odindi et al (2014) used Landsat OLI 8. ASTER satellite is another resource for thermal remote sensing. ASTER provides five thermal bands which is considered very high spectral resolution compared to Landsat. Mult iple thermal bands ( Table 4 ) provides the opportunity of using more accurate algorithms (multiple split window) for calculating surface temperatures. There are many studies that used ASTER images for measuring LST in relation to urban heat island effect such as Kato & Yamaguchi (200 5), Nichol et al (2009), Tiangco et al., (2008). Table 4 Thermal Bands of ASTER Satellite Images ( Votano et al., 2004 ) Band Number Spectral Range (m) Spatial Resolution 10 11 12 13 14 8.125 – 8.475 8.475 – 8.825 8.925 – 9.275 10.25 – 10.95 10.95 – 11.65 90 m 90 m 90 m 90 m 90 m 4 http://lands at.usgs.gov/band_designations_landsat_satellites.php

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48 As I discussed in the previous sections, exploring urban heat island effects through measuring ambient temperature, surface temperature, or their combination has its advantages and disadvantages. It is very important to understand that l and surface temperature is not exactly similar to the ambient temperature above that surface. Schwarz et al (2012) explored the relationships between land surface temperature (LST) and ambient temperature. They found that the location of weather stations is a crucial variable. In the evenings , the ambient temperature is higher than LST almost in all stations except those that are located in lawns. In the morning, the LSTs are very cl ose to the ambient temperatures . Ultimately , they concluded that air temperature and LST are related with relatively high correlation (Rs~0.60). The behavior of LST and ambient temperature are the function of day time (due to presence or absence of short w ave radiation) and the neighbor characteristics of weather stations. Modeling and simulation of the urban microclimate In order to understand how urban heat island forms we need to explain how energy comes to the ground level, is absorbed, and stored. The refore, we need to explain how climate forms in the urban scale. In this section, I review the literature of conceptualizing and parameterizing urban microclimate. This review w i ll shed light on the drivers of urban heat and the role of urban form elements . Scales of Climate Study Climate is a complicated nexus of variables and components. Studying the climate at the global scale could be a closed system. However, studying the climate at an urban scale is an open system which could be impacted by outer var iables. Therefore, it is important to identify the complications of studying climate at an urban scale. The urban climate is affected by the horizontal climate context and vertical atmospheric layers. A part of the atmosphere which could be impacted by the terrestrial surface is named “troposphere”. The thickness of this layer is about 10km. In a short term analysis (2 3 days), the affected atmosphere could be even thinner and is called “planetary or atmospheric boundary layer” (Erell et al., 2011, P.15). Figure 25 shows a conceptual framework of atmospheric layers in urban areas:

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49 UBL: urban boundary layer is all atmosphere above the built up area. According to Erell et al., 2011), the height of this layer is estimated about ten times. Mixed layer is the highest level of UBL which connects the higher atmosphere levels to the layers close to the surface. Roughness sub layer is the next layer which connects the mixed layer to the urban canopy layer. Turbulence caused by urban geometr y affects this layer. The lowest layer of the urban atmosphere is the urban canopy layer (UCL) and its height is equal to the height of buildings and other urban features such as tree canopies. Figure 25 Atmospheric Layers above Urban Areas (Erell, 2011) Urban canopy layer (UCL) is very important for microclimate formulation because it is affected both by surface properties and higher atmospheric layers. There is no consensus in defining these layers. For example, Arnfield (2003) defin es only two layers: UBL and UCL;

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50 Mirzaei and Haghighat (2010) also discuss only two layers, while Erell et al (2011) define four layers. Erell et al also argue that even the depth of soil is important in modeling microclimate. They also argue that the se layers are just a classification and in each context, depending on the properties of the terrain, soil, moisture level, etc. the height and depth of these layers would vary. In most simulations or microclimate formulations, UBL and UCL have been used to avoid the systematic complications. Formulation of Urban Energy Balance As I reviewed in the past sections, energy balance is the foundation of urban microclimate modeling. The basis of energy balance in urban environment is that the sum of input energy s hould be equal to the sum of stored and output energy (Erell et al., 2011). Energy input = energy output + change in stored energy The energy transfer between surface (built environment) and the atmosphere can be quantified through the estimation of energ y fluxes5. The general equation ( Equation 1) for urban energy balance is suggested by Oke (1988) and is used in other studies such as Arnfield (2003), Mirzaei and Haghighat (2010), and Erell et al (2011). Equation 1 Eneryg Balance of Urban Microcliamte + = + + + Where Q* represents the net all wave radiation, QF is the anthropogenic heat flux, QH is the convective or turbulent fluxes of sensible heat, QE is latent h eat flux, QS is the net storage heat flux, and QA is the net horizontal heat advection flux. Advecti on flux is transport of a property by a fluid, in this case the movement of heat by air. Oke (1988) suggested that at large scales, we can use this equati on written for an imaginary surface body as a proxy for an urban built environment ( Figure 26) . 5 Energy flux is the rate of energy transfer; Its unit is watt per unit area (wm2).

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51 Figure 26: Conceptual Framework of Urban Energy Balance for Microclimate Modeling (Erell et al., 2011) Ra diation plays the key role in this equation. Erell et al. (2011) separate radiation in to shortwave and longwave radiation. They suggest the Equation 2. Equation 2 Radiative Exchange Q*= absorbed radiation + emitted radiation = ( + ) ( 1 ) + Where Q* represents the net all wave radiation, Kdir is direct radiation (shortwave incident solar radiation ), Kdif is diffused short wave radiation that is reflected by other materials su ch as building walls, atmosphere, clouds, etc. , emissivity of the surface (or albedo), is the incoming longwave radiation emitted by atmosphere or other features in UCL, and is the emitted longwave radiation fro m the surface ( Figure 27) . To simulate microclimate in urban areas, depending on the scale of the study, we need to aggregate the influence of each feature (buildings and surfaces) on radiation absorption, heat storage, and radiation emittance. To relate u rban geometry and morphology to microclimate modeling we need to understand how features of urban form influence on the components of Equation 1 and Equation 2.

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52 Figure 27 Shortw ave (Direct and Diffused) and Longwave Radiation (Erell et al., 2011) Urban energy balance components and urban geometry (form) : In this section, I will review the approaches of urban surface interaction with microclimate components and variables. This review sheds light on the urban heat island generation processes. Identifying urban heat island drivers will help in proposing effective methods for heat miti gation as well. The following subsections explain the role of urban geometry and features on gaining, storing, and emitting energy. Shortwave radiation (solar incident radiation) and diffused radiation coming from the atmosphere: As I reviewed in the Earth’s energy balance section, the main resource of energy is coming from sun. The annual average of r adiation at the top of atmosphere is about 347 wm2. When this radiation in shortwave range (high energy) reaches to the surface of an urban area, it interacts with the materials. Two main process es may occur. The incident beam may be absorbed or reflected. As I reviewed in the “Science of energy balance” section, the quantity of each process depends on the properties of surface s . Absorption coefficient or emissivity defines how efficient a material can absorb radiation energy. Tabl e 5 shows the emissivity of some materials. As emissivity is a function of wavelength and temperature, there is no absolute value for each material. The number, however, helps to

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53 compare the efficiency of absorption and emission of different surfaces. One of the key issues in assessing the way urban surfaces interact with radiation is the emissivity of the surface. Table 5 Emissivity of Some Materials (Infrared Thermography Website6, Retrieved December 2014 & Erell et al., 2011) Su rface (material) Emissivity Albedo Asphalt 0.94 0.96 0.05 – 0.20 Concrete 0.71 – 0.90 0.10 – 0.35 Brick 0.90 – 0.94 0.20 – 0.40 Corrugated iron 0.13 – 0.28 0.10 – 0.16 white paint 0.85 – 0.95 0.70 – 0.90 Black paint 0.90 – 0.96 0.10 – 0.30 Glass 0 .80 – 0.94 0.70 – 0.90 Forest (deciduous tree canopy) 0.98 0.07 – 0.20 Grass 0.96 0.15 – 0.30 Soil (wet) 0.92 0.95 0.10 – 0.25 Soil (dry) 0.80 0.95 0.20 – 0.40 Reflection is another process that occurs for an incident beam. The more a surface reflect s the incident beam, the less energy remains for the absorption process (regardless of its emissivity value). A lbedo is an important property of materials that defines how effective a surface reflects the incident beam. Table 5 also shows the albedo of different surface types. The higher value of Albedo makes a material a better reflector. Another property of urban surface that impacts reflection is urban geometry. In urban areas an incident radiation may be reflect ed several times by building facades. This is called the “canyon effect”. The shape of urban canyons and their direction plays an important role in radiation penetration and reflection. Arnfield (1990) explored how canyon ratio and orientation can influence solar access and consequently solar radiation gain. In this study, Arnfie l d numerically explored the how different variables of canyon form and elements mitigate temperature for pedestrians. He concluded that st reet ratio and orientation, and building f acades are some potential variables that planners and designers could utilize for a climate responding design. Ali Toudert & Mayer (2006) studied the influence of street aspect issue (height to width ratio) and street direction on urban microclimate. They used ENVI met microclimate modeling application to simulate different scenarios in a city in Algeria as a case study with hot and arid climate. They found that street ratio 6 http://ww w.infrared thermography.com

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54 and direction has a strong influence on the temperature of the canyons and higher street ration (H/W) create a more comfortable temperature in the canyons. Bourbia and Awbi (2004) carried out research to measure shade coverage and its impact on creating a more comfortable temperature. They summarized that the North South street orientat ion with street ratio of 1.5 (H/W=1.5) and higher can produce shade that covers 40 t o 80 percent of street area. Erell et al (2011) argue that most physical and numerical models, generally, predict a higher albedo compared to the values suggest ed by exper imental and field studies. This is because of the complexities of urban environments, different faade materials, vegetation, people and activities, etc. S tudies using remotely sensed data show that the average albedo of cities range from 0.09 to 0.27 ( i.e . Brest,1987 and Erell et al., 2011; Taha, 1999; Arnfield, 1982). The albedo of most cities located in North America and Europe ranges about 0.15 (. 05). Some North African and Middle Eastern cities have higher albedo (0.30.4) “possibly because of unifor m, low rise” and integrated urban fabric (Erell et al., 2011, P:32). Figure 28 The Role of Street Ratio in Reflection of Solar Radiation (Erell et al., 2011) Sky view factor (SVF) is an index that has been extensively used to measure solar access. Erell et al (2011) explain how SVF influences radiation gain and reflection. Figure 29 and Figure 30 shows the conceptual framework for measuring sky view factor (SVF).

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55 Figure 29 Sky View Factor Measurement Method (Erell et al., 2011) Figure 30 3D Sky View Factor Measurement Method (Erell et al., 2011)

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56 Through reviewing the literature implicating the physics of radiation reflection , we can extract the following rules: The fabric of a city can create a rough surface (compared to plain areas). Increasing density (built environment density) can contribute to the roughness of the surface. Some studies ha ve proposed methods to measure the surface roughness. In this section, the roughness is considered as a variable influencing radiation reflections ; in a later section, I will review the influence of surface roughness on air movement s and turbulence s . Several studies used the surface roug hness coefficient to model the influence of surface shape on short and long wave radiation (Adebayo, 1990; Mills, 1997; Arnfield, 1984; Verseghy and Munro, 1989). Building height: building aspects reflect the radiation back to the ground. Therefore, a bui lding has more vertical surface to capture radiation and reflect it. Also, tall buildings create a deeper urban canyon. For a given street, a higher building (a narrower canyon) traps radiation through multiple reflections (from one side to the other side) and as a result increases the absorption (Erell et al., 2011). Uniformity and integrity of buildings: a more integrated body of buildings can reflect the radiation more effectively. Building height homogeneity is another variable that can increase the ref lection. Urban fabrics with varying building height are less efficient in reflecting the radiation back to the space. Street orientation: the general (dominant) street orientation is related the extent to which building facades are exposed to solar radiat ion. As Ali Toudert & Mayer (2006) found, the street orientation does not a significant role in the temperature of street canyons. Nevertheless, they found that East West streets could be marginally warmer than NorthSouth street orientation. The material of building facades: building faade could be made from transparent materials such as glazed walls. As a result, radiation can pass through and be absorbed in the building interiors. Reflective but not absorptive materials can direct radiation to the stre et surface and contribute to higher temperatures. Roof materials and their albedo: the color and type of material can also affect albedo. Lighter colors have higher albedo.

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57 Longwave radiation (emitted radiation from the surface) : As discussed in the sci ence of heat transfer section, Stefan Boltzmann Law states that any object with a temperature higher than zero kelvin ( 272.15C) emits energy through radiation. Therefore, all features and elements in urban areas emit radiation back to the atmosphere. Thi s energy loss help s cit ies to cool down especially over the nights. This energy will also heat up other features in urban environments such as buildings and its reflection will reach to other surfaces as well. Therefore, all variables discussed for short w ave radiation, will be important in heat flux modeling. For measuring long wave radiation the emissivity of a material play an important role . Figure 31 Long -wave Radiation Emitted from Surfaces Convective sensible heat flux: If the temperatures of surface s and atmosphere are different, then the energy moves from higher temperature toward lower temperature. Convection is the movement of air. The size of convective heat flux depends on two variables: (1) the magnitude of the tem perature difference between surface and adjacent air; (2) the resistance to heat transfer. Erell et al (2011) defines the heat transfer equation as: Equation 3 : Convective Heat Transfer = ( )

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58 Where QH is the rate of convective heat exchange (Wm 2), hc is the convective heat transfer coefficient (Wm2K1) and Ts and Ta are the temperature of the surface and the air. In this equation the complexities are because of convective heat transfer coefficient (hc) because it is dependent on the quality of air, air flow speed, and the geometry of the surface. Some empirical studies have defined hC coefficient. For example, Clark and Berdahl (1980) proposed some values for dif ferent conditions that could be used as a general rule. They proposed hC as 0.8 if the wind speed is very low (less than 0.076ms1) and as 3.5 when the surface is warmer than ambient air and wind speed is lower than 0.45 ms1. Erell et al., (2011) provide a summary of the proposed coefficients for several conditions. Most models estimate the convective heat transfer coefficient for a simple and flat surface while in the urban environment, surfaces have complex geometry. Most microclimate models ignore these complications. One important issue that should be considered here is that the complex geometry of urban fabric can decrease the wind speed close to the ground and as a result can increase the convective heat flux . Also geometries with higher exposed faces (area) can transfer heat more effectively that flat surfaces). Turbulent sensible heat flux: Air turbulence or wind flow moves the molecules and particles above urban environments. The heated air (adjacent to the ground) moves around and carries the warm er or cooler air to other places. Urban fabric influences the wind flow on the ground (UCL) and in the sublayer (UBL). For measuring turbulent sensible heat flux both horizontal and vertical movements are important. Modeling air turbulence is extremely complex and high resolution simulations require significant computational power. As the wind patterns in a region are usually divers e in different seasons, it requires neighborhood scale simulation to understand the function of urban fabric in impacting air turbulences. Computational fluid dynamics (CFD) is a common approach to simulate wind flow in urban areas. Some CFD models calculate air pressure , speed, and direction and their relationships with temperature, radiative heat fluxes, and latent heat fluxes (presence of water and vapor). Mirzaei and Haghighi (2010) argue that CFD models can produce more accurate results. However, considering the amount of details needed as inputs and modeling requirements (computation power) running CFD microclimate models could be a challenge. Mirzaei and Haghighi (2010, P: 2195) argue that: “ On the other hand, theoretical problem is related to the unmatched temporal

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59 and spatial resolution of the phenomena which occur inside a city. For example, atmospheric and canopy scal e turbulence cannot be modeled in a same scale of time and length” . To solve the scale issue, most models are designed for two scales: (1) mesoscale and ( 2) micro scale. Several studies used CFD to explore how form can influence microclimate in cities (i.e . Capeluto & Shaviv, 2002; Ramponi & Blocken, 2012; Hooff & Blocken, 2010) . Latent heat flux: Latent heat flux is related to the energy absorbed or released by moisture of soil, biomass, surfaces, and atmosphere. Latent heat is important in the process of precipitation or evaporation. From the urban form perspective, permeable surfaces can keep soil moisture and mitigate surface heat. Impervious surfaces, on the other hand, are dry and can potentially heat up quickly. In addition, vegetation adds moisture to the air through transpiration and mitigate s heat through latent heat flux. Plants also absorb moisture from deep soil and bring it to the ground. Tree canopies not only create shaded area, also absorb heat through evapotranspiration (Erell et al., 2011). In some studies, the amount of vegetation in urban areas and permeable surfaces are used to es timate latent heat coefficient. (i.e. Arnfield, 2003; Takebayashi & Moriyama , 2007; Masson, 2000). To incorporate latent heat in microclimate simulation, some studies used water budget through estimating inputs and outputs. For example, Takebayashi and Moriyama (2007) used water budget to simulate the contribution of green roofs in heat mitigation. In another study, Brethier and Andrieu (2006) parameterized water budget model in urban areas. Also Nakayamaa and Fujita (2010) used a water budget model to measure the influence of water holding pavements in the heat budgets of urban areas. Thermal storage: The absorbed heat is stored in the material and mass of the objects and surfaces. Each object has a capacity to store heat as a function of heat capacity coefficient and its size ( engel & Turner, 2004) . Since the amount of stored heat plays a key role in energy budget of the system, we need to understand the amount of stored heat. Stored heat usually makes objects warmer than the ambient air over nights. As a result, these objects start transferring heat (through radiation and conduction) to the ambient air. Over a daily cycle (24hours) the storage flux is usually mi nor

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60 because surfaces gradually accumulate heat in summers and release it in winters. If we ignore the yearly variation, the daily balance would be zero (gain over day times and loss over night times). Storage heat in urban areas (or heat capacity) is usually measured through assigning an average for each object type in urban areas. It is usually very difficult to assign a precise number to each object. Erell et al (2011) suggest that we could estimate an average value for each object type. They provide a l ist of values for each type ( Table 6) . These estimated numbers simplif y calculation of thermal storage heat flux in microclimate models. This helps to classify objects in urban areas and assign the estimated values to them. Table 6 : Thermal Properties of Typical Objects and Materials in Urban Areas (Erell et al., 2011) Anthropogenic heat: Human activity in our modern world requires energy. We burn fossil fuels to heat up or cool down buildi ngs and to run cars and industries. This energy produces some work (machinery functions) and heat. Erell et al (2011) formulated the magnitude of anthropogenic heat flux through three main variables: QF = QV + QB + QM

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61 Where QF is total anthropogenic heat f lux, QV is the sum of inputs form vehicles, QB is the sum of heat produced by buildings, and QM is the sum of heat produced by metabolism. In this approach, the heat produced by industrial activities will be still considered in heat produced by buildings. Ichinose et al (1999) measured the spatial distribution of energy consumption and its contribution to urban heat island. They identified the energy consumption and heat generation of different sectors such as households, commercial, manufacture, transport. As transportation is one of the heat generators in urban areas, the spatial structure of a city could be a key variable which influences the amount of VMT ( Vehicle Miles Traveled). In general VMT could be a good measure for estimating QV. Klysik (1996) carried out an experimental study to measure the anthropogenic heat flux of different neighborhood types in Lodz, Poland. For example, he measured that the “new areas of blocks of flats (about 30 Km2) have a mean annual flux of 35 Wm2”. Also he found that t he mean annual flux for central part of the city which has some industrial uses are about 40 Wm2. He also found that the winter anthropogenic heat flux in winters are higher than summers for this city. These studies show that we could assign an average value for each land use type or for each neighborhood type to estimate the anthropogenic heat generated by buildings (QB). There are also estimates for VMT in each city. The Census Bureau provided VMT at census block groups in 2000 which could provide a fai rly precise spatial distribution of vehicle related anthropogenic heat flux in cities. Heat released by human metabolism and presence in urban areas is a minor proportion of anthropogenic heat flux. Erell et al (2011) believes that this number is only 23 percent of total anthropogenic heat flux. Most studies have ignored this parameter. Erell et al has summarized the suggested estimated measures of anthropogenic heat fluxes. Table 7 shows the average annual anthropogenic heat flux for several cities. For example, Los Angeles, CA has a relatively high per capita of energy use compared to Vancouver. This high per capita in Los Angeles is mostly because of high VMT. Table 7 Average annual anthropogenic heat fl ux (Erell et al., 2011)

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62 Urban heat island mitigation Most of the available literature about urban heat mitigation is focused on increasing the albedo of urban surfaces including roofs and pavements through using light colors and high albedo materials. A nother widely proposed solution ha s been urban forestry or planting vegetation. Akbari and Huang (1987) studied the potential of vegetation in reducing the use of summer time cooling systems in residential buildings. This research shed light into the ways landscaping impacts microclimate of cities and as a result the energy consumption. Rosenfeld et al (1995) reviewed the mitigation programs in Florida and California. They suggested that any heat mitigation program needs (1) to run test procedures for cool materials, (2) to assemble cool materials databases to guide and support the building development industr y , architects, industries, and developers, (3) to incorporate cool roofs and tree canopies to build energy performance codes and other amendments, (4) and to offer incentives to complement standards and codes. They also measured the impact of cool roofs and higher albedo roof colors in reducing energy consumption. Their experimental studies in California and Florida showed that cool roofs can reduce the energy use by 20 40%. Rosenfeld et al (1995) enumerated a number of policy programs that could encompass heat mitigation policies. Bretz et al (1997) studied Sacramento, California. They estimated that about 20% of the buildings and 10% of roofs have low albedo. They estimated that if the albedo of these surfaces were elevated, the overall albedo of Sacramento city could be raised by 18%. This improvement in albedo could produce a significant saving (about 10%) in energy consumption.

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63 Rosenfeld et al (1998) argued that in Los Angeles , the annual residential air conditioning bills can be reduced by about $100 M through adopting strategies such as increasing the albedo of surfaces and planting shade trees. They argued that this saving results in the reduction of emission and consequently smog in Los Angeles’ weather, which benefits the city indirectly. They estimated the indirect benefit could be about $360M. Takebayashi and Moriyama (2007) study some variables including the surface temperature, radiation, wat er content ratio, etc., in relation to green roofs and high albedo roofs. After comparing different surface types they find that on a surface with high albedo (white paint), the sensible heat flux is small because of the low net radiation (most portion of the shortwave radiation is reflected back to the sky). On the green surface, the sensible heat flux is small because of the large latent heat flux (through evaporation) although the net radiation is large. This study, through a numerical modeling, shows that high albedo and water contents can significantly reduce urban heat and should be addressed in mitigation policies. Akbari and Rose (2007) studied four major US metropolitan areas at high resolution to measure the surface type precisely. They examine the land use and land cover types in urban areas and find that about 2941% of the area is covered by vegetation, 1925% is covered by buildings, and 2939% is covered by paved surfaces. They find these surfaces a potential area of change and suggested planti ng vegetation and increasing the albedo of surfaces as some viable solutions for mitigating urban heat. EPA (2008) summarizes that vegetation and green/cool roofs are the main heat mitigation strategies considered by standards and policies. However, they m ention heat mitigation through modifying urban geometry could be a potential area that has not been considered well. Memon et al (2008) carr ied out a review study and summarized the proposed strategies for heat mitigation. They also stud ied the potential temperature reduction and energy saving. Again, they focus ed on increasing albedo and vegetation as the main strategies. Urban geometry and morphology was not among the variables they reviewed ( Table 8).

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64 Table 8 : Proposed mitigation strategies, maximum potential temperature reduction, and possible energy savings (Memon et al., 2008) It is evident that urban mitigation policies are highly focused on albedo and vegetation. Although there has been good research identifying the role of urban geometry on forming urban heat island effect, most studies have ignored the influence of urban morphology in heat mitigation. One reason could be related to easier process of increasing roof albedo or pla nting vegetation compared to modifying urban form and morphology needs a long term plan and raises highly complicated policy issues. Another reason could be that most of these studies are coming from engineering or environmental study disciplines and the p lanning dimension is very weak. Planners need to study the role of policy and space making in heat mitigation. Urban heat island mitigation in policy documents in Denver As discussed in the previous section, most mitigation strategies were focused on incre asing vegetation and surface albedo. This is also a visible track in policy documents. As urban heat mitigation is a relatively new issue, in most planning and design policies there is no direct attention or intention to address the urban heat issue. In re cent years, adaptation and mitigation plans or climate action plans (which are mostly advisory not mandatory) are raising the urban heat issue. In this section, I briefly review the climate adaptation and mitigation plans . The City of Denver prepared its f irst Climate Action Plan in 2007 which was mostly about reducing GHGs. In 2014, a new Climate Adaption Plan was published. Contrary to other cities’

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65 climate action plans , an increase in temperature caused by urban heat island effect is one of the main conc erns of this plan. This plan also has addressed the possibility of extreme heat events in the Denver Metro area. In that report, the literature of urban heat island and extreme heat events is reviewed with the support of some evidence in the region ( Table 9). However, in the proposed strategies urban heat island mitigation is limited to “Reduce urban heat island effect through infrastructure such as shade trees, urban gardens, green roofs, and lighter colored hardsc apes” (City and County of Denver, 2014, P:75). These tasks are assigned to Department of Public Works (DPW). Denver’s climate action plan suggests that building codes should address issues related to roof colors and materials issue. Other suggestions are r elated to adaptation to extreme heat events. For example, the plan suggests a weather advisory and notification system to notify high risk populations . They also suggest preparation strategies for emergency services, urban infrastructure, public cooling shelters, and education. Denver Climate Action (2014) also suggests some mitigation strategies including: Preparation of a tree and shade master plan, Offering a list of approved trees for planting in public realms, Preparation of storm drainage master plan , Promoting the energy efficiency of buildings and reducing anthropogenic heat, Installing high albedo hardscape when resurfacing roads, multi use paths, and city parking lots, and identify life cycle costs associated with concrete vs. asphalt , Requiring permeable pavement for a portion of parking lots larger than one acre , and Integrating climate change into planning and zoning considerations. Overall, the Climate Action Plan (2014) proposes some good strategies and directions. However, this plan needs to translate to codes and policies that could change the general planning and design practice. It seems the distance between setting appropriate goals and objectives and policy tools is not filled yet. One of the main strategies of this plan was “integrating climate change into planning and zoning considerations”. The latest zoning which was adopted in 2010 suggest s promotion of urban vegetation but still does not force heat mitigation in practice. Comparing the climate action plans for Boston (2014), Los Ang eles (2012), and Denver (2014) reveals that Denver has taken a very progressive approach in paying attention to urban heat

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66 island effects and heat waves. Denver proposes s ome significant strategies and objectives which are consistent with the current liter ature. Los Angeles and Boston do not even consider urban heat mitigations in their plans. Although Denver’s plan is a considerable move in identifying and addressing the urban heat issue, there is a gap between high level goals and objectives and policies. Table 9 : Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of Denver, 2014) Conclusion of microclimate section Climate change is causing extreme situations harming natural and human systems. Clima te change drivers and consequences are strongly related to energy use, transportation behavior s , and development patterns in urban environments . Therefore, there are two main tasks for planners from this perspective. First, how planning and design policies can mitigate climate change; second, how planning and design can make cities more resilient and adaptive to minimize damages. Considering these tasks , c limate change mitigation and adaptation should become (if they are not yet ) two of

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67 the main priorities of planning policies. This strongly entails the reframing of planning theories, goals, and objectives. Even sustainable development , as the current dominant planning paradigm , does not meet all climate change mitigation and adaptation strategies. This mean s, revision of application review processes (appraisal processes) , main policy tools, growth control strategies etc. also need fundamental modifications . P lanners should revise planning theories, techniques, methods, education, and ethics to respond to the e merging issues . Also, planning research need s to scrutinize any planning policy or development strateg y to highlight the ways policies and development strategies influence climate change drivers and effects in short and long terms. Climate change exacerbates both the urban heat island phenomenon and heat waves. Except for the anthropogenic heat flux (a small portion of total heat flux related to urban heat island) produced by mechanical processes such as cars, industries, and heating/cooling systems , ur ban heat island is mostly the result of built environment configuration. Nevertheless, overlapping effects of heat waves and heat island s could be a signific ant risk in urban environments. There is a potential for improving urban microclimate through regul ating form and built environment elements. The science of urban heat is well e stablished now. The drivers of this phenomenon are identified in the literature. Heat mitigating strategies such as increasing albedo and vegetation are highly emphasized. However, other strategies and elements such as urban canyons and building forms are less studied . T here remains a gap in the literature in translating the identified strategies to planning and design policy and practice. Urban heat island research has been most ly p u rsu ed in engineering disciplines and there are few studies from planning perspective. In general, urban heat is not well formulated in the planning and design discipline . Planning scholars need to connect the scientific aspects of this phenomenon to m itigation practice. To conclude and summarize this section , I provide a list of urban form elements that science shows could influence heat absorption, storage , and reflection (emission). This list will be my guid e to explore policies which could influenc e the microclimate of cities. Table 10 Urban form elements and microclimate modeling Form Element Variable Influenced Energy Fluxes Surface materials (3D environments) Albedo Reflection/absorption of radiation Emissivity Absorpt ion/emission of radiation Conductivity Advection heat flux

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68 Impermeable or permeability of surface Latent and radiate heat flux Moisture contents (indicating latent heat) Latent heat flux Mass (buildings) Total mass on the ground being capable of st oring heat (heat capacity) Conductive heat transfer Urban Fabric Orientation of streets and buildings (Radiation gain in facets and aspects) Radiative heat flux Urban canyons (sky view factor) (street width, building heights) Radiative heat flux Gener al surface roughness of a city (homogeneity and integrity of building and urban fabric) Radiative heat flux , advection flux, convection flux Surface Geometry (homogeneity and integrity of building and urban fabric) Radiative heat, advection, convection Landscaping Vegetation (type and cover) Radiative heat, advection, latent heat, convection Anthropogenic heat Number and type of cars, trucks, and buses (burned fuel). Anthropogenic heat flux Heating/Cooling systems of buildings Anthropogenic heat flux Machinery used in industries Anthropogenic heat flux

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69 A general literature review of planning and design codes and standards in urban development In this paper, I review urban development policies with an emphasis on downtown development. Although t his is a general literature review about development polices, I highlight policies that could influence urban microclimates. I discuss historical and political contexts of policies to inform the processes through which they are shaped and implemented. For example, zoning is being used extensively to control growth and development in most American cities; understanding how zoning is devised and its main goals and conflicts will help to criticize its current function as a development control tool. The literat ure review in relation to policies which shape urban form will help me to formulate the relationship between policy and heat mitigation. I focus on policies such as zoning, subdivision regulations, and design guidelines that shape urban morphology. The way different form elements influence urban microclimate is extensively discussed in the first paper of my literature review, “Climate Change and Microclimate.” After reviewing the literature of development control policies and microclimate, I will be able to discuss how policy can change microclimates of cities and the future direction that would help planners and designers to mitigate urban heat island effects. In this paper, first, I review the literature of urban design theories, the current challenges of urban design, and the future challenges, paradigms, and conflicts. I review urban renewal approaches and downtown development policies. Second, I review the general literature about urban codes and standards. Third, I review the subdivision regulations. F ourth, I review zoning policies and codes, their types, and political economic issues. The fifth section is about design guidelines. Finally, the last section is a discussion about the policies that are designed to mitigate heat. Design theories Reviewing urban design approaches benefits this paper because it highlights strategies and methods dealing with the design and regulation of public realms. We need to depict the direction in which design theories have evolved and the paradigms that could be dominant in the future. Key public spaces in each city are usually located in downtown areas; therefore, activity and built environment characteristics matter for any policy evaluation in downtowns. Policies and economic forces have been among the main drivers in shaping American downtowns. Policies usually are

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70 founded upon planning and design theories. The way we frame urban design as an issue affects the practice of design and policy making. Urban design, with its current meaning, was a response to rational desig n and planning approaches in the modern era (Lang, 2005). Before and during the modern era, many efforts in planning and design influenced the design and planning practice. For example, Garden City by Ebenezer Howard (1965) , and the Neighborhood Unit plan of Clarence Parry (1929) proposed clear strategies for public realms and configurations of built environments. Critics of rational planning and design efforts encouraged planners to focus on social and economic aspects of planning rather than physical desi gn (Fainstein, 2010). For example, public resistance and social activism encouraged by Jane Jacobs (1961) directed planners toward advocacy planning focusing on the politics of planning and theorizing planning as public and political activity (Campbell & M arshall, 1999). Most research projects and studies related to urban design are project oriented (case oriented). Each project provides new experiences, successes and failures. Lang (2005) elaborately explains the nature of urban design and its domain, typologies, and procedures through examining these projects as case studies. As illustrated in Figure 32, he categorizes typologies of urban design through ‘ a three dimensional matrix of types in terms of (1) the desi gn and implementation process (2) the product type and (3) the major paradigm that structures the process and gives form to the product ’ (P:56). These three criteria help to understand design processes and their products. Jon Lang (2005) criticizes archite cts who think ‘anybody who can design a building well is capable of designing a good city’. As a result, architects have proposed, and in some cases, built cities (e.g. Radiant city by Le Curbusier, mega cities proposed by Norman Foster, and new towns such as Brasilia designed by Oscar Niemeyer).

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71 Figure 32 A Typology of Urban Design Projects (Lang, 2005) To understand the drivers of change in the design process of public realms and changes in planning approaches, we need to eval uate the bigger picture of public space design in the theories of planning and policy making. Madanipour (2006) proposes a theoretical framework to define the role of urban design in the development control process and its future challenges. He argues that in order to appreciate the significance of urban design and its evolution, we need to recognize the main trends and changes that cities are experiencing (Carmona, 2010). Madanipour mentions globalization as a relatively new phenomenon (in the history of urbanization) which influences the economies of cities and consequently impacts their design and planning priorities. Although globalization is an example of the current trends and forces that are influencing cities, there are other issues such as climate change, which seems to be one of the major concerns in the current century (Thornley & Newman, 2011). Influences of the global economy have been studied from planning perspective. Manuel Castells (1988) proposed the “spaces of flow” theory to investigate how information technologies have revolutionized time and space in urban contexts. Space is a product of many variables including economy, culture, and history. Castells’ theory explains how

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72 market players and capitalism have changed their strategies produci ng new forms and places in different spatial scales. Madanipour (2006) focuses on structural changes in economy, labor division, means of production etc. He argues that new trends in the economy have forced cities to compete with each other and this has changed the development market and consequently city centers. Madanipour (2006) concludes that “design is a helpful tool for development friendly authorities that try to reduce the tensions between exchange value and use value, between development and cons ervation, between economy and society” (P: 183). Urban space has been studied as a product of capitalism (or generally the dominant economic system) by new Marxists. David Harvey argues that urban space is shifting to become the consumption space rather than the production space (Harvey, 1991; Harvey, 1996; Harvey, 2007). Harvey argues that capitalism uses the postmodern culture to produce flexibility in use, investment, and space. As Lefebvre (1991) frames the concept of space in the critical discourse, modernist capitalism used space as a place for production while, since the mid 20th century, postmodern capitalism has produced space to gain the exchange value and uses space to promote consumption culture. Zukin (1995) believes that capital is intertwined with cultural systems of a city. In a capitalist planning system, there is a competition among cities to gain more exchange and use value through producing a high quality space that promotes the consumption culture. Consumption is the key component in the economy of cities. Food, art, shopping, and entertainment are different manifestations of the new culture and each demands its own space. From a new Marxist perspective, urban space could be one of the productions of capitalism through market forces. Accor ding to Madanipour (2006), planning systems have been a medium through which these forces interact and shape the outcome. Local authorities are forced to behave similar to a corporation to maintain their revenues. There are two main forces influencing planning and development control systems. One is the market forces and the other one is social movements. Market forces tend to utilize planning system in favor of producing more profit or protecting and increasing exchange and use values. On the other side, s ocial activism and public movements demand more democratic processes leading to sustainability and affordability. Most of current environmental regulations are the outcome of social campaigns protesting against social and environmental justice degradations (Haughton, 1999).

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73 We also can study the evolution of urban design practices in the context of planning theory changes. According to Fainstein and Campbell (2012) planning approaches changed from proposing long term comprehensive plans to providing a regulatory system. This pushes planning systems to focus on small projects rather than the whole city, which is titled incremental planning. These changes have made planning systems more plan based, visionary, and more regulatory aiming to create higher qualities in public spaces (Madanipour, 2006). This change is more visible in the proposition of form based codes and design guidelines studied by Elliot (2012), Punter (1999), Talen (2012), Lang (2005), and BenJoseph (2005). Assuming that urban design guideli nes and landscape regulations now are a dominant dimension of planning systems (Aherm, 2013), exploring this issue will lead us to ask: what kind of qualities are in the current agenda to be addressed either in projects or in design control standards? In a ddition, who defines what a good design is remains a key question. Madanipour (2006) claims that policy makers of cities, in the new global economy, have more emphasis on competing with other cities to attract more investment and more creative classes. A b etter quality of space can increase exchange values, attract more people and businesses (Gottdiener, 2010). Urban design should deal with some challenges for serving a better outcome. This approach fits with New Marxian theories of consumption space. Citie s need a more vibrant space for shopping, dining and entertainment, which increases the exchange and use value of properties (Knox & Pinch, 2014). The city that provides a happier and more attractive place for residents and especially the creative class, c an gain more investment and surplus. The New Marxian theories, however, raise a conflict in their arguments. If capitalism as a dominant economic system encourages cities with higher qualities of open and public spaces, they are contributing to create a better place for all classes as well; all citizens can benefit from a walkable and bikable city with vibrant centers even if businesses benefit from too (Feagin, 1998). Making a city affordable never has been the ultimate goal of capitalism. This is the miss ion of planning authorities to advocate for vulnerable and low income groups through encouraging affordable housing development or providing other services. If the economic system and other forces encourage a specific space (production space or consumption space), planning theory and practice should identify these patterns and highlight the advantages, disadvantages, and impacts on other human and natural systems. If there are trends that harm nature or social justice or

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74 exacerbate climate change, planners need to regulate development to control those trends (Punter, 2010). Recent design and planning paradigms encourage advocacy and environmental planning to protect the rights of social groups and the quality of natural systems. Graham and Aurigi (2007) beli eve that public spaces in cities have been occupied by privatizing and commodifying them. They advocate for social groups to have more extensive access in using and designing public and open spaces. Goheen (1998) also argues that the public sphere in citie s should be democratized. Urban design movements since the 1980s have attempted to improve urban life in public spaces. Gaffikin et al (2010) investigated the roles of public spaces in ‘contested cities’. They propose a review of the historical and contemporary role of urban design in shaping social space and interrogate the feasibility of using urban design to facilitate more integrated cityscapes. Jacobs and Appleyard (1987) in “Toward an Urban Design Manifesto” articulate that the goals of urban design a re to achieve a better urban life or “an urban fabric for an urban life” including livability, identity and control, access to opportunity, community and public life, and an environment for all. Each of these goals can be studied from a different perspecti ve. Here, I think we can connect the major concern of current planning and find the overlap with urban design, which is climate change. A public space should be designed with respect to the future challenges such as global warming to protect urban life in extreme events. Also, the design should be consistent with major climate properties. Urban design in Denver, CO should respect to the cold winters and hot summers while using the same form in Seattle would not make such differences in urban microclimates. The quality of the built environment in public spaces is a key variable in improving urban life through promoting walkability and diversity of use. Therefore, built environments should have better aesthetic and social qualities (Rogers et al., 2011). The form and elements of spaces, also, influence climate conditions such as microclimate, shading, and thermal comfort (Watkins et al, 2007). Jan Gehl (1987) in his thorough study of pedestrian activity in public spaces, categorized outdoor activities as nece ssary, optional, and social activities. Optional and social activities are highly dependent on the quality of design. He doesn’t mention the climatic characters of cities and the way they can affect these activities, perhaps because twenty five years ago, global warming and climate responding design was not a major concern. However, Mahmood Tavassoli (2009)

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75 explored organic design of Iranian historical cities in the central part of the country with the hot and arid climate and found that public spaces are d esigned to mitigate high temperatures and create comfortable conditions in outdoor public spaces ( Figure 33). William Whyte paid attention to climatic elements in the design of public spaces and people’s behavior. He noted that in chilly days of winter, sunlight attracts people. He explains “what people seek are suntraps and the absence of winds.” He found the significant role of trees in public spaces. Trees are beneficial in winter because of blocking wind and in summer for the pleasant shade. He found that even on very cold days, small parks are quite habitable. He criticized the design of high rise buildings which create intense wind at ground level. He believed “Wind tunnel tests on models of new buildings are now customary, but they are not made with people in mind.” He mentions different cities such as Seattle and Chicago where high rise buildings damaged the public space by making them inhabitable and unwalkable. Whyte found the presence of trees incredibly useful for public spaces and argued that trees should be close to sitting spaces to provide aesthetic and microclimate benefits. Figure 33 Yazd (Left) and Gonaabaad (Right) Climate Responding Organic Design in Iranian Cities (Tavassoli, 2002 P:19) As I reviewed the literature of urban microclimate in the previous chapter, urban form and built environment characters influence urban microclimate. Thermal comfort creates a better place for all social groups including the elderly, children, and disabled people ( Capeluto et al, 2003). Planning and design theories need to identify strategies to mitigate heat and embed them in policies and regulations. These activities also are related to climate change mitigation and adaptation. Revi ewing the current design theories reveals that there is a clear trend toward climate responding design. However, there is still a gap between the literature and policies to implement heat

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76 mitigation strategies in practice through modifying built environmen ts and form elements. In short, we need to reform design and planning theories leading to the practice to redefining a good design with respect to prospective climate challenges and to make cities more resilient. Urban Renewal Policies Climate change mitigation and adaptation strategies require some modifications in built environments to produce more energy efficient forms (indoor and outdoor) and to emit less GHG. Existing public spaces, urban fabrics, and buildings should be modified to meet the goals and objectives of climate change mitigation and adaptation policies. Modifying existing built environments will demand urban renewal efforts. Urban renewal projects could be a title for any intervention in physical environments with an intention to improve i t (Roberts & Sykes, 1999). Therefore, urban renewal shares its historical evolution with planning history (Hall, 1996). In some literature, urban renewal approaches are categorized into premodern era, modern era, and postmodern era (Cooke, 1990; Gordon, 2003; Knox, 1987). In some literature, World War II was a benchmark in urban renewal policies because it caused a need for reconstruction of neighborhoods and providing social housing. In this section I classified urban renewal approaches into three categor ies: (1) the period of bulldozer and dictating topdown interventions intending to clean the built environment with emphasis on physical improvement, (2) the comprehensive approach to rehabilitate with focus on social rehabilitation, and (3) the economic development through revitalization of downtowns and developing catalyst sites. In the first era, the goal of planning and intervention was obviating health issues through cleaning slums and low quality neighborhoods (Peterson, 1979). In European countries t he redevelopment directed by Haussmann in Paris (1870) is a benchmark attempting to “treat over crowded” neighborhood suffering from crime and disease through demolishing existing buildings, building wide streets and boulevards, sewer systems, and water ducts (Gandy, 1999). Carmon (1999) studied urban renovation in the US through clearance of land sites by public agencies and found that slum areas were demolished to construct shopping centers, offices, and conventional centers in the years after World War I I. Carmon (1999) found that between 1949 and 1964 only less than one percent of federal funding for urban renewal was allocated to relocated households. These policies raised criticisms for neglecting social aspects of such extreme approaches. The challen ges between Robert Moses and Jane Jacobs over renovation projects in New York city in

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77 the 1960s is a classic debate in urban planning considered as a benchmark for reviewing renovation policies (Gratz, 2011). The second era is an outcome of social movemen ts questioning consequences of totalitarian approaches to urban renovations. In the US after the 1960s many movements advocated civil rights and bottom up processes in city planning to reduce poverty and empower low income groups (Cullingworth, 1993). As a result, public opinion in planning processes became more important and demolishing a neighborhood to build a shopping center or office building was not possible anymore. In that time, many federal and local policies addressed poverty as a driver of blight in neighborhood. These programs aimed to decrease social injustice in cities. As Cullingworth (2009) mentions, President Johnson’s policies for “the great society” and the “war on poverty” were examples of federal policies. In addition, local governments and public agencies tried to take advantage of public participation in proposing and implementing plans. Cullingworth (2009) quotes from President Clinton (1995) that “the days of made in Washington solutions, dictated by a distant government, are gone. Instead solutions must be locally crafted” (P: 295). Another important program aiming to empower communities was Community Development Block Grants (CDBG) signed by President Ford in 1974 for improving low and moderate income neighborhoods. All these approaches and policies led to stronger bottom up or participatory community development plans (Cullingworth, 2009: 306). I review economic development very briefly as the third generation of urban renewal policies. In a study by Gibson and Prathes (1977), soci al programs for supporting housing were examined to evaluate their efficiency in improving communities and the life of vulnerable people. According to this study, in most cases these programs were not effective. Storm (2008) identifies political coalitions between public agencies (city officials as representatives) and private corporations to invest significantly in renovating neighborhoods and downtowns. These projects also include catalyst projects that are targeted as development stimulation or capital a ttraction, which can improve the general economy of cities. In addition, there is more interest in preserving historical land marks and converting them to cultural attractions, hotels, and entertainment centers to market the city as a tourism destination. Another recent trend in economic development strategies is related to the attraction of high tech startup firms and technology clusters (Yigitcanlar et al., 2008). These “knowledge intensive

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78 industries” are dependent on creative class and entrepreneurs and can attract young generations of recently graduates into the labor force (Corey & Wilson, 2006). These startups are formed by students usually graduated from local universities and in most cases have strong relationships with faculties and research center s in fields such as software development, multimedia, robotic inventions, and biotech (Wu, 2005). Wu explores the reasons and factors that a city can attract these clusters and finds that first the presence of universities are a key factor in generating su ch groups and feeding them through cutting edge research; second, the relationship between universities and big industries that can provide funding for research projects plays a crucial role. However, there are still questions about the efficiency of this approach in helping vulnerable classes systematically (O’Mara, 2007). Improving the economy of the city through these clusters attracts many well paid employees and consequently raises housing and service prices. Low income classes barely benefit from this type of economic growth and eventually they will need to move to peripheral areas to find cheaper housing (McCann, 2007). Different strategies of urban renovation approaches including economic development and physical reformations (renovation or reconstruction) are important because they are the only window for preparing our cities for future challenges. Street height ratio, building materials, open spaces, landscaping opportunities, pocket parks, green/cool roofs, etc. are key variables for heat mitigatio n that require appreciation by urban policy makers. Downtown development policies Downtowns are becoming the heart of urban life again (Heath, 2001). This leads to several processes that gentrify city centers and attract investments, creative classes, and activities (Zukin, 1987; Wilson, 2004). Many cities are implementing urban renewal and design projects to create higher quality public spaces and more walkable environments (Isenberg, 2005). This provides new opportunities to modify urban form, improve spatial structures, and adopt climate change mitigation and adaptation policies (Yow, 2007). An urban design approach that incorporates urban microclimate strategies would create a more comfortable temperature for users of public spaces (Nikolopoulou et al., 2001). Besides improving social activities in public realms, there are energy and health concerns that heat mitigating policies could contribute to. Birch (2009) studied downtown populations from 2000 to 2007 and found that the residential population li ving in downtowns rose 12 percent. He argues that the relationship between

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79 downtown growth and overall performance of the economy in cities is significant. He found that most cities in the West and South are growing while most declining cities are located in the North East and Middle West. He advocates that providing high density residential mixed use can contribute to the livability of cities in general. The new paradigm in downtown development is moving away from the heavily single use pattern of office d evelopment. The new paradigm encourages dense, walkable, mixed use with a considerable residential component providing small size housing. Public uses such as universities, hospitals and schools should be integrated with the fabric of downtown without disc onnecting the walkable and commercial nodes. Birch shows that local governments tend to expand downtowns and dense mixed use districts. Another dimension that city leaders have attempted to improve is public spaces and their amenities. In Birch’s study, m any cities started heavy investment in redesigning downtowns to attract more users and increase property values. He provides the example of several cities that used gardens, parks, retail streets, etc. Birch argues that downtowns are more resilient against economic depression and during the last economic depression (since 2007) downtowns show higher growth compared to other areas (Birch, 2009; P: 151). Storm (2008) explores two dimensions of change in downtowns including changes in the physical shape and changes in the economic and political forces impacting downtowns. Changes in the physical environment of downtowns are as an outcome of planning and design processes tending to encourage walkable and mixed use environments. Exploring the changes in politica l processes of downtown development has been discussed by political scientists and sociologists and is less addressed by planners. This discourse studies various stakeholders involved in the governance procedures, which includes elected officials and burea ucrats, corporate leaders and business associates, and neighborhood organizations or social groups. In the 50s and 60s downtowns were heavily influenced by corporations and business elites. Their decisions about moving their investments could impact the pe rformance of business districts significantly. Availability of land in suburbs connected by highways could provide more financial benefits making corporations more resilient against property market collapses. Strom (2008) studied the historical relationships between “business leaders” and “entrepreneurial mayors and development officials, leveraging federal urban renewal funds to shore up downtowns.” She believes although these relationships are contested by public groups,

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80 “economic elites” have still a co nsiderable share in decision making of downtown reshaping processes. Strom questions to what extent the corporate power still matters in the interaction with other stakeholders. She concludes that in most major American cities, downtowns are not the heart of corporate power anymore. Land use of downtowns is a mix of cultural, entertainment, and retail, which means corporations own less land and have less interest in holding political power. Strom reviews approaches which encourage people to perceive downtow ns as a place for leisure activities and entertainment including art galleries, walking places, sport venues, and retail to explore which political, economic, or social forces are stronger in shaping the built environment of downtowns. Strom concludes (2008) that the economic base of ownership and land uses are changing from corporations, bankers, and manufacturers to city officials, real estate brokers, and maybe university presidents. She mentions that presence of nonprofit and public officials has crea ted a different development agenda compared to private entities and corporations in the past. This has resulted in the inclusion of public and nonprofit officials in leadership boards of downtowns. However, it seems that in most cases, real estate partner s stay as an effective player in downtown development processes. Strom’s argument is not proved in her paper and remains a hypothesis. She assumes that although real estate developers are a dominant player in decision making of downtown reshaping, their roles as investors are substantially different than corporations and bankers because their interests are different in the long term and short term. There is a gap in the literature exploring how changes of stakeholders of downtown investors and owners have i nfluenced decision making processes in leadership boards and negotiations with city officials in designing PUDs, for example. Some economists believe that downtowns could be strong attractions for tourism through providing cultural festivals, vibrant day a nd night life for diverse groups. From this point of view preservation of historical districts and buildings, development of museums, theme restaurants, and cultural events can promote the economy of downtowns and cities. In this approach, large districts of offices can degrade the quality of downtowns for tourism attraction (Xie, 2006). Kemperman and Borgers (2009) articulate how unique shopping opportunities with cultural themes can promote downtown tourism. They found that shopping supply, with strong ac cessibility supported by physical characteristics and preserved historical particularities are important aspects improving route choice behavior. In this study, they concluded that physical improvements could increase the economic performance of downtowns.

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81 Over the past twenty years, local economic growth played an important role in urban politics and planning in American cities. Local governments adopt increasingly entrepreneurial economic development strategies to attract capital and startups. According to Leitner (1990) local governments behave entrepreneurially because of economic interests, or because autonomous political agents draw the attraction of entrepreneur industries. To identify these trends, it is necessary to analyze how economic and political processes, operating at different spatial scales, negotiate to influence policy making and local government actions. This is then helpful to explain the evolution of downtown development policies.

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82 Codes and standards The identification of opportuniti es in the current policy frameworks for heat mitigation requires understanding the historical and political context of policies. Several policies and planning tools shape built environments. Each policy addresses specific aspects of built environments. For example, zoning regulates building envelopes, its location in parcels, and open spaces, uses etc. Subdivision codes regulate building height ratios, street shapes and orientation and so on. All these parameters are important variables in influencing the m icroclimate of cities. In this chapter, first I review the general discussion related to codes and standards, their importance, contradictions, and complications. Then I review subdivision codes, zoning codes, and design guidelines. Codes and standards are “the hidden language of place making” (BenJoseph, 2005). Planning and regulating standards share a long history. Marshal (2011) uses “urban code” to address and study all codes and standards including building codes, landscaping codes, subdivision standa rds, etc. I believe separating codes from planning practice in general could be misleading because in most cases codes have been the instrument of implementing the general plan, master plan, or comprehensive plan. In this section, I review the works and re search of three authors who have explored codes (urban codes) specifically and their influence on urban form: Eran BenJoseph, Emily Talen, and Stephen Marshal. All of them review the history of urban codes and their emergence; nevertheless, they offer their own methods for embarking on this subject. My focus in this paper is not reviewing the history of codes and their evolution. Instead, I review how the codes produce built forms in recent planning practices to extract parameters that can impact urban mic roclimate. Ben Joseph (2005) provides a dialectic historical review exploring the contexts in which codes were offered and treated. He studies how these codes could cause problematic ambiguities, homogenization, and stereotyped developments. I will discu ss his approach and findings later. Marshal (2011) reviews several international studies in different countries to show how codes evolved in their context and across nations. He concludes with categorizing these standards and offering some future directions. Talen (2012) picks a practical method through which she examines codes and standards by presenting examples on the ground to show how the existence or lack of codes can influence urban form.

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83 In his historical review, Ben Joseph (2005) shows several exa mples of regulationsthat implemented standards and codes that were generalized and globalized. These standards were not designed to consider local specifications such as climate and culture. These standards generate similar buildings, shapes, and form. His points out that preparing codes respecting local particularities is an expensive and time consuming process and many local governments borrow codes that already were prepared. He calls codes the hidden language of place making and probes the history to fi nd evidence reflecting the existence of codes. American placemaking code (language) has been replicated around the world. Ben Joseph identifies two main variables in placemaking which are traceable almost in all standards. The first variable is the conce rns related to public health and sanitation. This variable has been a strong inspiration to regulate space and protect communities from disease and hazards such as fire. The second variable is related to the “desire for consistency” to facilitate preparing and implementing codes and construction of new neighborhoods. Many codes and standards carry features and characteristics from their historical creations and modifications similar to genes. However, many of the drivers that contributed to the creation of such forms do not exist anymore. One of the examples that Ben joseph (2005) points out is fire codes shaping buildings and subdivision layouts. He argues that these codes usually overestimated the risks to release agencies from any responsibility. Fire codes significantly impact urban microclimate. For example, street width, building heights, and roof/faade materials can influence radiation absorption and reemission. Fire codes significantly restrict density and some shading strategies. Adopting fire code s has been considered a high priority in most communities and cities without evaluating and modifying them to address the local issues including climate parameters. In addition, there is no considerable innovation in the design of fire fighter equipment to fit in narrower streets or taller buildings, even though the technology would allow us to provide smarter services. The improved methods of computer simulation to evaluate different parameters such as climate and energy issues, risk assessment, etc. can l ead to better and more efficient standards. BenJoseph points out a controversial point that the emphasis on social and economic aspects of design after the era of modernism, has pushed the focus on physical design back and it is time to address physical a spects of design and planning to deliver a balance between social aspects and the physical environment.

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84 I think the peripheral role of technology and simulation for physical design and planning has not been significant until recent decades because the advances in computer applications were not profound enough to deal with some real complicated issues of the real world. In addition, adopting a set of prepared, documented, and examined standards, such as fire codes, is the result of legal complexities of dea ling with possible harms. Local governments prefer to sacrifice improved planning in exchange for guarantying maximum safety. The decentralized governance system in the US is another reason because preparing such standards for local communities need a grea t deal of expertise and funding and fragmented governance system generating small local governments encourage them to adopt such national codes without worrying about legal consequences. Marshal (2011) summarizes his cross national review of codes and standards through categorizing them into three types based on their purposes. The first are codes with utilitarian purposes designed to provide health, sanitary, and safety such as fire related codes or even separation of industrial uses from residential areas . These codes protect properties against nuisance. The second category of codes serve a visionary approach. These codes aim to create a specific urban form and qualities through, for example, preserving historical fabrics and creating walkable neighborhoods. Design guidelines are an example of codes with such purposes to create or preserve some characters in downtowns and core urban areas. The third type of codes tend to create a better condition for different social groups especially for vulnerable groups. Provision of affordable housing and inclusionary approaches are examples of codes with such purposes. Talen (2013) highlights the need for understanding the ways rules shape built environments and for exploring “the effects and the neglect of rules” (P: 2 ). She presents several examples that show how bad rules can neglect the consequences in built environments. Talen (2013) shows ( Figure 34) that the municipal codes require a developer to provide one parking lot for every 250 square feet of commercial floor area. She argues that the outcome of this policy is very poor because of extensive parking lots and unwalkable spaces, which exist because of the absence of other rules to prevent extensive parking lots. She suggests some policy alternatives that could mitigate the vast parking areas including: parking maximum, limitation on size of surface parking lots, reduction of parking for mixeduse projects, walkways through parking lots, and required bicycle parking. Park ing lots also play a considerable role in the microclimate of cities. Extensive impervious and dark surface of parking lots can increase radiation absorption and consequently

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85 can exacerbate urban heat islands. Therefore, some form elements such as large sh opping malls surrounded by parking lots not only degrade walkability of cities but also they impact microclimate. However, the microclimate issue has not gained enough attention from planners and designers. Figure 34 Shopping Mal l in Chandler, Arizona, a product of neglecting the side effects of rules (Talen, 2013; P: 2) Talen (ibid) identifies the right problem effectively and spots the right location to illustrate how poor policies create an unpleasant unwalkable space. I believe, however, her approach does not address the main problem. In other words, although the parking requirement policy forces such extensive parking spaces, the existence and location of such a large shopping mall, its relationship with streets and neighborhoods, offering single use with minimum landscaping qualities, and its segregation from the spatial structure of the city are also seriously questionable. Talen organizes her policy evaluation into three categories: use, pattern, and form. In each category she brings examples that regulations and rules have left a visible footprint on the ground. All three authors introduce interesting methods for exploring the role of policies in shaping built environments. However, none of them offer a systematic method to identify the problem at

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86 different scales and hierarchies. For instance, they do not offer a method to identify poor outcomes of policies and finding the root of the problem from different perspectives including deficiencies in regional and city scale poli cies (with respect to spatial structure of cities), zoning (or any sort of district regulation systems), use distribution policies, building envelope regulations, and landscaping standards. Any poor form is probably the outcome of a combination of all thes e deficiencies. Also it would be helpful that such a policy evaluation method could categorize different aspects of a poor urban form implying issues such as (for example) walkability and bikeability, energy inefficiency, social exclusion, safety, and lack of identity issues. To frame a more precise policy evaluation method, I suggest a framework with at least two dimensions: (1) the subject of policy (related to form) such as land use regulations or building envelop control; and (2) type/scale of policy. Subdivision regulations The main goal of subdivision regulations is dividing large pieces of land into smaller ownership lots (parcels). In the Standard City Planning Enabling Act (1928) a subdivision is defined as a tool to divide land into lots or parce ls for the immediate construction or future use and selling of land. Subdivision regulations are very important because they shape streets, blocks, lot sizes, and lot patterns. These parameters create the structure of built environments that hardly change over time. Also, these parameters play an important role in impacting urban microclimate. Lot size, street width, building location in a lot, building height limitations, front and backyards, vegetation refuges in streets all impact microclimate. The form produced by subdivision plans, as a structure for neighborhoods, changes very slowly and as a result it is very important to evaluate the consequences of subdivision plans in our environment and climate. Cullingworth (2009) identifies variations in defini tions of subdivision regulations in different states. The way terms such as “previously developed” and “improvement” are defined is one of the major differences. While zoning controls the development of individual parcels, subdivision regulations control t he way a developer divides land and shapes a group of parcels, street alignments, grades, widths, drainage and sanitary facilities, location and size of easements and right of ways, fire roads, lot size and configuration, and other required facilities or uses for the neighborhood considering the size and scale of subdivision (Cullingworth, 2009). Although zoning

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87 and subdivision regulations share some common methods to regulate the pattern of development, they may apply at different phases of development projects. Subdivision regulations are prior to zoning in most projects. In fact, street patterns, lot shapes, and block shapes are tied together. Changing one will affect the other. In order to study the ways these variables are regulated, we need to study z oning, subdivision regulations, building codes, and street design standards in an integrated framework. Southworth and BenJoseph (1995) argued that rigid structures of suburban development standards have influenced built environments extensively. Reviewing these standards reveals that they are an outcome of old, outdated, and complex standards formed by engineers, financial institutions, road building industries, fire protection and police agencies. Southworth and Ben Joseph found the root of suburban deve lopment patterns in the 19th century when several standards were proposed for improving industrial cities. For example, in 1844, “the First Report of the Commissioners of the State of Large Towns and Population Districts, published in London” proposed some standards for revising street design such as regulating street width, pavement, etc. (Southworth and BenJoseph, 1995, P. 66). According to Southworth and BenJoseph (1995), Olmsted and Vaux and Co in a plan for Riverside, IL, proposed some design guidel ines which are clearly borrowed from British standards; these standards included setback (about 30 feet), curved streets, width of 30 feet for residential streets, pedestrian walkways on both sides, and planted strips of trees for separating road way from pedestrian pavements. The emergence of these standards is not an accident. They are a response of designers to issues of their time such as sanitation, overcrowding, new modes of transport and safety related issues. The necessity of regulating movement of different vehicles forced policy makers to enact street width and features in subdivision regulations. For example, in 1919 the Bureau of Industrial Housing and Transportation provided standards for street width, vegetation, pedestrian pavements, etc. Thes e evolutions led to Clarence Perry’s neighborhood unit in 1929 with the goal of creating a safe neighborhood, which was a response to traffic congestion. Clarence Perry and Thomas Adams provided clear ranges of street width for different street hierarchies and block shapes (Lawhon, 2009). Federal policies including home financing and insurance strategies (e.g. Federal Housing Administration) forced a uniform standardization in new developments, mostly in suburbs.

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88 Southworth and BenJoseph (1995) mentioned how other organizations (e.g. Urban Land Institute and Institute of Transportation Engineering) contributed in the evolution of subdivision standards. Currently, most local governments use the publication of ITE (1965 and its revisions in 1984 and 1991) Re commended Practice for Subdivision Streets in which there are fairly rigid standards: “Right of way: minimum 60 feet, Pavement width: 3234 feet, Curb: vertical curb with gutter, rolled curbs not recommended, Sidewalks: at both sides, minimum width 5 fe et, Planting strip: 67 feet with sloping towards street, Cul de sac: maximum length 1,000 feet, with 50 feet radius at end, Parking lane: 8 feet, and Driveway regulated with minimum width of 10 feet for one car, with 20foot wide curb cut (5 foot flar e at each side)” (Southworth and Ben Joseph, 1995, P. 78). Subdivision regulations provide an important regulatory system for controlling development. However, studying the ways in which these regulations can shape the built environment should be in relation with zoning and other rules. In addition, most neighborhoods were laid out in the early twentieth century. Changing the layout of existing neighborhoods seems almost impossible. Therefore, street patterns and widths are unlikely to change. Nevertheless, buildings and lots change more frequently and as a result, regulations such as zoning could potentially make a difference in urban forms. Subdivision regulations remain valid for laying out new neighborhoods, which is not very common any longer. Zoning M ost planning theorists and practitioners agree that zoning is a key tool in the American planning system. Zoning aims to control development, growth, land use, and the shape of cities. Zoning is probably the most influential planning tool on the form of buildings and parcels and the distribution of land use. It is widely accepted that zoning shapes the third dimension of cities. Therefore, zoning has a substantial impact on microclimate as in the microclimate chapter I discussed how building form can influe nce microclimate. Willis (1993) believes that the form of

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89 New York is shaped by two important planning efforts: (1) the grid layout, with broad North South avenues and multiple narrower East West streets, as a product of the Commissioners’ Plan of 1811 pro posed by the New York State Legislature; (2) the Zoning Resolution of 1916. The motivations behind these policies are different. Considering that growth management policies tend to limit development of suburbs and advocate infill development or urban core intensification, the current central issue of planning is probably not subdivision plans any longer. These trends, however, raise the importance of zoning as the main regulatory tool for the intensification of urban areas and particularly of downtowns. As Elliot (2008) argues, to understand why zoning does not work, we need to understand how it is supposed to work or the reasons that it was offered in the early 1910s. In this section, first I briefly review the history of zoning and the context in which it was devised. Then I review different types of zoning and new approaches including form based zoning. Finally, I review the criticism of zoning and its political economy. Zoning History: Conditions Leading to the Enactment of the 1916 Ordinance in the New York City In the 1870s and 1880s, in Manhattan (New York) due to the rapid growth of skyscrapers, residents began to complain about the lack of light and general environmental qualities. In response, the State Legislature enacted some height regulations f or constructing residential buildings, explicitly stated in the Tenement House Act of 1901. Soon, developers found how some flaws in regulations of the Tenement House Act of 1901 could be utilized to extract maximum surplus from lots. Exploiting these flaw s, in 1915 the 42story Equitable Building was built without setbacks to its full height of 538 feet in Lower Manhattan and cast a sevenacre shadow over neighboring buildings, affecting their value (Salkin, 2000). The emergence of such buildings to supply office space in a high demand market raised concerns for the future of Manhattan and set the stage for the nation’s first comprehensive zoning resolution (City of New York, 2014). Zoning in the 1910s was motivated by two main issues: (1) avoiding nuisanc e (i.e. polluting uses), and (2) access to sunlight and air and protecting properties from tall buildings as obstacles. Having access to climate parameters (light and air) motivated people to regulate development (Salkin, 2000). The Zoning Resolution of 1916 was a relatively simple document to regulate height and setback and to designate residential districts excluded from “incompatible uses.” The Zoning

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90 Resolution was frequently amended to be responsive to major shifts in population and land use patterns ( Cullingworth & Caves, 2009). According to Willis (1993) the idea of stepping back the upper floors to allow more light to reach the street had first been suggested in the 1890s and in 1907. Several architects including David Boyed offered a formula to calc ulate amount of setback for each floor. The formula used street width and lot size as factors to define the setback. Height limitations depended on the size of lots, meaning that larger lots could have higher height limitations. This encouraged merging par cels to create a large lot and as a result to reach higher height limits. The number of required elevators (occupying a considerable amount of a lot), the zoning formula for reaching height limits, and the economics of maximizing rental space, all together , led to larger lots and buildings. Considering that the majority of original lot sizes in Manhattan were 25 by 100 feet (divided in the Commissioners’’ Plan of 1811), assembling such large parcels could be difficult. Willis argues that by the 1960s and 80 s these drivers could produce huge setback structures covering a whole city block. Building heights and pyramid shapes are important variables influencing urban microclimate. Therefore, the birth of zoning affected and to some extent regulated urban microc limate. Zoning was a practical tool designed to deal with immediate problems, unlike former planning practices such as comprehensive planning and the city beautiful movement that were more visionary (Elliot, 2012). Zoning was an antithesis for the chaotic development of tall buildings and shrinking open spaces. The city authorities needed a tool to stop such a trend. On the contrary, most planning practices before the twentieth century and even during the modern era were inspired by the utopian approaches ( Fischel, 2001). From this perspective, zoning delivered efficiently in a short term in the context of New York city. The special context and economy in Manhattan made zoning an important regulatory tool limiting capricious developers. This success attracte d other states and local governments to follow this experience but in a very different context (BenJoseph, 2005). In New York city, zoning became a tool to protect the public’s right to have access to light and open space. Hood (1931) claimed that zoning was the first step toward public participation in the process of decision making in the planning system because it enabled the public to advocate their rights against developers. In the rapidly growing context of New York in the 1890s and 1900s

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91 dominated by thirsty developers to maximize office space and invest in tall building construction, zoning could protect public interests. Therefore, from the beginning, the goal of zoning was protecting the property rights and value which could be degraded by their neighbors. This became an important cornerstone of zoning later in other cities. Fischel (2001) scrutinized this concept and articulated his argument to understand the political economy of zoning and entitled it “Home Voter Hypothesis”. He articulated how zoning is utilized to protect prosperous neighborhoods against any change proposed by local governments to promote diversity and affordability. The Standard Act made zoning the main tool of planning in the country, comparable to a police power with its flaws and usefulness. Zoning was a rational response to chaotic developments in New York city in the 1900s. Implementing the same framework with some nuances in very different contexts in which the nature of problems is totally different could cause several systematic problems. Elliot (2008) claims that after 1928, many states adopted zoning and comprehensive plans but still there were a confusion whether zoning is a plan itself or part of plan, and whether zoning is a master plan or an instrument to impleme nt a master plan. He also points out that in most cases zoning and the comprehensive plan were adopted at different times and could not have completely logical relations. Cullingworth and Caves (2009) argue that zoning is an exercise of police power in re gulating developments. The American Constitution confers this power upon the states, delegated to local governments. All states in the US have passed legislation enabling municipalities to implement zoning controls. In the Enabling Zoning Act, it is expli citly stated that zoning should be in accordance with the comprehensive plan. Planning theorists consider zoning as a tool for implementing planning visions and ideas. However, some scholars (Punter, 1999; Elliot, 2008; and Cullingworth & Caves, 2009) beli eve that in most cases, zoning became more important than it was supposed to be and instead of planners, lawyers took control. In addition, the Zoning Enabling Act explicitly states that zoning should be accompanied and consistent with a comprehensive plan (Elliot, 2008). However, in many cities there is no comprehensive plan and zoning remains the only planning system. In the Zoning Enabling Act, there is no clear procedure articulating how zoning should follow the comprehensive plan in the long run. Culli ngworth and Caves (2009) believe that in those states with a strong growth management plan, zoning is more consistent with the comprehensive plan. Overall, I believe, the

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92 nature and origin of zoning and comprehensive planning are disparate; as a result, br inging these two needs strong review boards with significant negotiation power to conquer inconsistencies and conflicts raised by diverse stakeholders. Euclidean zoning shaped in the 1920s remained the same, without significant alteration, until after Wor ld War II. The main driver of change was the onset of automobile domination in the streets. For example, Denver adopted its first zoning ordinance in 1923 and its second ordinance in 1957. The 1957 ordinance covered new topics like parking, loading, the em ission of heat, glare, radiation, fumes, and vibration, and special zone lot plan. By 1994 the ordinance code of Denver became very complicated. Table 11 shows number of districts and their subcategories in Denver from 1923 to 1994. Table 11: Numbers and Categories of Denver Zoning Districts from 1023 to 1994 (Elliot, 2008: P.12) 1923 1957 1994 5 residential 3 business 3 commercial 2 industrial 5 residential 6 business 1 office/industrial 1 park 3 special 3 industrial 16 residential 12 business 7 mixed use 2 office 1 park 3 industrial 1 planned unit development (PUD) Total=13 Total=19 Total=42 Zoning Techniques: Euclidean zoning is still the backbone of zoning techniques. However, s everal techniques are offered to make zoning more flexible, inclusionary, and accommodating. Elliot (2008) classifies the evolution of zoning to three categories: Euclidean zoning, modifications on Euclidean zoning, and form based zoning. Parolek et al (2008), as proponents of form based codes, call the modifications on Euclidean zoning as some “band aids” to address the problems of zoning. In this section, first, I review these techniques (types) intended to make zoning more flexible as an evolution proces s, then, I review form based codes as a new approach. Planned Unit Development

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93 Planned Unit Developments (PUDs) are considered a method to ensure some standards in development of important sites. PUDs are some special lots and districts which usually have one owner. Local governments outline PUDs when they intend to have a general plan setting the general uses, activities, and forms without proposing precise standards. In fact, the purpose of PUDs was a method to break the rigidity of firm regulations and i mplement zoning through a process. They use review boards to require developers to guarantee qualities beyond traditional zoning codes. This negotiation process (between cities and developers) gives developers and owners some flexibility to offer a site plan and gain optimum benefits. In other words, local governments invite owners to negotiate about the details of the plan, which is not a usual process in traditional zoning. PUDs could be considered as a contract between local governments and owners (devel opers). PUD leaves room for innovation and bargains ( Brewster et al , 2008). PUDs don’t have a perfect outcome. Since the quantity and quality of development is not precisely defined, planning of complex urban systems such as infrastructure and transportati on is difficult at the beginning (Elliot, 2008). As a solution, in most cases, such as Denver Union Station, development of the required infrastructure is also the responsibility of developer(s). Another solution has been offering the general concept of PU D districts with fixing density as a cap. Then, the general plan specifies total amount of development such as density and built area, total housing etc. PUDs can potentially convert planning practice to a negotiation process between local government and developer(s) to reach a win win agreement (Buttny, 2010). In this process, planners are supposed to advocate for vulnerable groups and public interest. However, this is not an easy game because such projects involve heavy investments and powerful groups and lobbies. Elliot (2008) believes that usually developers and land owners have an upper hand in the negotiations. He believes that in most cases PUDs did not bring innovation or quality for cities while they involved a very heavy work load for planners to process. The quality, experience, and skills of local governments’ employees, who review the final site plan proposed by the developer, matters to ensure that the outcome would benefit cities (Whittemore, 2014). PUDs are important in downtown development policies because they provide a good opportunity for local governments to create some specific rules for downtown districts. For example, in Denver, recently, the downtown is developed under a PUD plan named Union Station.

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94 This part of downtown is heavily r enovated through constructing new buildings. The special location and amount of infrastructure required for this project was very complicated. Regular zoning is not detailed enough to address all issues in such a project. PUDs also are very important from urban microclimate perspective because planners could force more details for landscaping, form, building sizes, etc. PUDs provide a customizable framework in which urban heat island mitigation policies could be embedded effectively. Performance codes: The performance zoning technique is a response to the fixed parameters or rules that could be inconsistent with performance variations. In other words, instead of rigid physical metrics, the expected performance would be measured. Although many cities did not replace Euclidean zoning with performance zoning, they adopted some performance metrics instead of fixed measurements (Brewster et al, 2008). Performance standards mostly applied for industrial uses where the impact or outcomes of the activity is more vis ible and measurable. Elliot (2008) believes that the idea of some regulations and standards could make zoning more flexible. The reason that performance codes did not replace Euclidean zoning, however, was that defining and determining the standards is a complicated process. Determining actual thresholds for most problems such as pollution, noise, and vibration need a thorough research for each item. The more difficult issue related to performance zoning is reviewing the plan to approve that buildings or infrastructures are adequately well designed to mitigate the negative consequences (Cullingworth and Caves, 2009). Regular planners are not capable of such reviewing processes which needs a more scientific background in several disciplines. The third probl em is related to predictability. Euclidean zoning provides a fairly predictable form while the performance zoning may guarantee to not disturb the neighborhood but it does not provide a clear image of built form and as a result may create a heterogeneous o r unexpected form. Different forms also may cause some unpredictable results that planners could not predict. Performance codes could be a feasible strategy to address the influence of buildings and built environments on urban climate issues such as urba n microclimate. The amount of radiation absorption and reflection, color or albedo of roofs and surfaces, and extensive impervious surfaces could be regulated. For example, the Walkie Talkie building in London followed all predicted standards, building cod es, and planning codes. However, the outcome was a building with a curved

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95 glass faade. The curvature of the faade reflected intense radiation and caused several damages in its neighboring buildings and streets. This example shows that standards may fail in predicting the consequences. In most cities, performance codes are fused with Euclidean zoning through enriching the standards. Spot zoning Spot zoning emerged when property owners or land owners wanted to have some special conditions which were not possible under the regular codes. Elliot (2008) named this as a "loophole" and claims that spot zoning is the application of zoning to a specific parcel or parcels of land within a larger zoned area. While zoning regulates the land use in whole districts, s pot zoning makes unjustified exceptions for a parcel or parcels within a district. Floating zoning In floating zones, the exact location of uses and lots is not specified. Instead, total number and area of required services and uses are required, in addit ion to limiting parameters such as density, setbacks, FAR, and other standards for the whole site. According to Cullingworth and Caves (2009) “it is important to consult each state’s enabling statute to determine how flexible courts will be in allowing municipalities to use the floating zone concept. One state may view it as essentially spot zoning. Another state may allow its use as long as the proposed use does not conflict with the master plan” (P: 101). Cluster Zoning Cluster zoning addresses suburban residential neighborhoods to protect natural landscape and environmentally sensitive features. In this technique, instead of determining density and form of each lot, the general density of a site is limited (Elliot, 2008). Overlay zoning Overlay zone was a method to add some extra regulations for some areas. Flood plains are a good example of overlay zones for adding some floodrelated regulations no matter what the main zoning is. Variances

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96 Variance involves a relaxation of ordinances. Variance leaves sp ace for negotiation and interpretation whether it harms public interest or not, whether it is an unnecessary hardship or not, and whether the spirit of the ordinance is harmed or not. Incentive Zoning Incentive zoning was developed initially in the 1950s and 1960s to encourage desired development through incentives, again allowing for greater flexibility for the developer and discretion for the community. Developers gain the bonus when they provide an amenity or a feature which is not required in the zoni ng ordinance but it could benefit the public. Developers usually do not provide these amenities because they are not profitable; therefore, local governments use incentives such as higher limits, FAR, etc. to encourage developers. The initial applications of incentive zoning occurred in Chicago and New York city, and allowed for increased height and/or reduced setbacks in exchange for public amenities such as plazas or streetscape improvements (Elliot, 2008). Density and other bonuses were initiated in the late 1970's and early 1980's in New Jersey and California, respectively, to encourage affordable housing construction. Density and FAR bonuses, fee waivers, expedited review, and reduced parking are now relatively common incentive techniques in zoning. The incentives are usually intended to further the community's goals for affordable housing, historic preservation, environmental protection, ground floor retail use, and transit oriented development (Cullingworth and Caves, 2009). Density bonuses for affordable housing are often a good example of problematic incentives. Some developers may profit more from building at lower densities, resulting in larger homes, than taking advantage of the density bonus. The few bonus units may result in lot and unit sizes on the remaining market rate units being reduced and selling for less. As a result, communities today often require minimum affordable housing levels ("inclusionary zoning") but then provide a bonus for additional affordable units too. There is a delicate balance between what a community requires versus the use of incentives to encourage certain types of development, as well as trying to match the appropriate level of the incentive to the bonus. Form based code:

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97 Elliot (2008) believes that Form Based Codes (FBC) are the third big change in zoning history. Parolek et al (2008) claim that FBC is a new approach in development of regulations because it is “vision based” aiming to require all developments to follow the detailed vision set at the beginning of the plan. From their perspective, then, FBC itself is zoning regulations and comprehensive plan at the same time. They praise FBC because it “is holistic, addressing both private and public space design to create a whole place, including buildings, streets, si dewalks, parks, and parking.” Form based Code Institute7 (FBCI) defines (2014) FBC as a land development regulation technique that provides predictable forms and walkability in the public realm through the creation of desirable forms and mixeduses (rather than separation of uses). According to Elliot (2008), the principles of FBC originated in the New Urbanism movement which is rooted in the work of these planning practitioners. Katz (1994) presented examples of walkable and less car dependent developments, with respect to neighborhood character. Duany and Plater Zyberk also published several works reflecting the experience of walkable and compact neighborhoods (Kelbaugh, 1989; Duany et al, 2001). These works contributed significantly to the improvement of relationships between street and buildings through regulating building facades and frontages. FBC borrows the Traditional Neighborhood District (TND) concept from smart codes to determine the character of neighborhoods based on their locations in the ci ty using transect zones ( Figure 35). These zones are classified as rural to urban transects. Blocks close to the core offer higher densities, mixed uses with public frontages, while blocks close to the edge of citi es have a more rural (suburban) character. In FBC, regulations are also organized in the framework of transect zones. According to Parolek et al (2008), the six transect zones should be modified considering the characteristics of local communities. These z ones can be categorized into smaller subset zones (e.g. T4a, T4b, etc.). 7 The Form Based Codes Institute (FBCI) is a non profit professional organizatio n dedicated to advancing the understanding and use of form based codes. FBCI pursues this objective through three main areas of action.

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98 Figure 35, Transect Zones : Rural to Urban Characters (FBCI, 2014) We can identify five main elements in FBC: regulating plans; building standards, streetsc ape standards or public standards; administration as a project review process, and definitions including a glossary to ensure the precise use of terms (FBCI, 2014). The framework of standards in FBCs is open. This means that cities can adopt additional sta ndards such as architectural, landscape, signage, and environmental resource standards. Standards of building frontage design, facades, and public realm elements are concepts that the traditional zoning approaches do not cover. Transect zones accommodate r egulations as a guiding framework. These standards, however, were part of design guidelines which some cities adopted as a separate regulatory system. Classifications of regulations could be adopted differently in cities. For example, Elliot (2012) collect ed several implemented FBCs in different cities and provided a handbook of FBC development. He proposes seven categories (Table 2) of regulations: Blocks/Alleys; Buildings; Streetscape; Parking; Retail; Historic preservation; Public improvements. Public space standards deal with parks, plazas, other open spaces, and thoroughfares including their elements and amenities. The term thoroughfare is used instead of street or road to avoid conventional terms, as Parolek et al (2008) argues. The standards of street features are very detailed. They regulate street profiles (including width and lanes), landscaping, plantation, and amenities such as benches, bicycle facilities, parking spaces, lightings, etc. In the case of civic spaces (parks and plazas) there are les s clear standards. Some hints and templates are provided in the guiding documents but the standards do suggest many limitations. Other standards suggested by FBCs are considerably detailed. FBC tends to preserve the characters of neighborhood through det ermining all details of building envelopes including openings, deck, and features. This makes the implementation of FBC in the existing neighborhoods

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99 very complicated because the standards should preserve the character of neighborhood while following the l ogic of transect codes. These two issues sometimes conflict and as a result, planners need to require public participatory processes if they attempt to change the character of those neighborhoods. This is probably the most critical point in implementing FB Cs because applying changes that are not consistent with existing character could raise public resistance, then using property rights to fight back. Therefore, from a legal perspective, FBCs are not different with traditional Euclidean zoning because they are still grounded in the context of property rights protection. Certainly, FBC is a significant improvement of zoning techniques, providing a more comprehensive framework for regulating the built environment. After about 1015 years from the creation of F BC, experience of its implementation in large and medium cities is limited. Even cities such as Denver that claim to have replaced the traditional zoning with FBC have used a hybrid version of traditional code and FBC. To examine if the excitement of FBC e mergence is realistic or optimistic I need to first explain what FBC offers then juxtapose benefits with the criticisms of traditional zoning to see the extents of successes or failures. FBC may offer some new ideas and standards about public spaces that a re neglected in the American planning system. However, FBC is not a ground breaking idea as it is pitched by some of its proponents such as Parolek et al (2008). In the recent years (since the 1980s), large cities have been using design guidelines as a com plementary component of planning review process. Cities such as Seattle, San Francisco, and Washington have been using complex guidelines to force developers to provide public amenities, walkable spaces, and regulated facades similar to FBC’s standards. T he main criticisms about the Euclidean zoning is its failure in protecting the vulnerable groups’ interests. Although FBC offers more mixed uses, this does not mean that FBC provides more affordable housing units. Nevertheless, higher densities advocated b y FBC may increase housing supply in general. Also, FBC is still involved in property rights and is not able to go beyond it. The significance of property rights in hindering provision of affordable housing through changing the character of a neighborhood may be considered a systematic issue rooted in the American Constitution. Another well studied problem of Euclidean zoning is its inclusionary effects. It is still unclear to what extent FBC can solve this problem. Because most mixeduses are offered in u rban core

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100 areas including downtown areas, this can partially solve the problem of single office use in downtown areas. However, the problem remains the same in suburban neighborhoods with the domination of single family housing units. In spite of praises devoted to FBC, they still have some conceptual problems. Other than the above issues, FBCs simplify urban structures with the concept of transect zones. Many cities do not follow the simple pattern of a monocentric structures. In these cases, there are s everal specialized centers with diverse activity types. Also, the distribution of social classes in neighborhoods can add more complexities. FBCs do not have clear strategies for such complex conditions. FBCs ignore social, cultural, and climatic contexts of cities and neighborhoods. Each of these variables need a deliberate unique design guideline to address local issues. FBCs are offering stereotyped standards for very diverse contexts which intentionally ignores particularities of each context. FBCs are another step forward in improving the practice of planning and the traditional zoning. They consolidate design guidelines and the traditional zoning regulatory system. This hybrid model equips planners with a more efficient tool to promote walkability and liveability of cities. FBCs are the outcome of long term experience in modifying Euclidean zoning. The FBCs affords planners for more innovations leading to the improvement of standards. New technologies of policy and design evaluation enables planners to suggest smarter standards fostered by new measuring equipment. Error! Reference source not found. shows an example of FBC developed for Colombia Pike, VA regulating blocks/alleys, buildings, streetscape, parking, retail, historic preservation, and public space improvement. These regulations offer smaller lots sizes, less parking lots or smarter parking standards, and mixeduse development. These standards are more progressive than traditional zoning standards but a re very similar to design guidelines which have been used for more than thirty years. FBCs could be important policy shift that can potentially mitigate heat. FBCs have certain rules about building frontages that are capable of creating more shade in stree ts and in public realms. They improve landscaping policies such as planting in streets and parking lots, and green roofs. In general, the flexible transect framework and context base of FBCs provide good opportunity to regulate microclimate related policies in different morphological contexts.

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101 Political economy of zoning As discussed in the previous sections, zoning was designed to protect property value. In fact, zoning was extensively used to protect neighborhoods from changes degrading the quality of lif e. Separation of uses and prioritizing them was inspired by the idea of protecting residential areas from pollution. However, this led to nimbyism (not in my backyard) and gives right to owners to avoid any unwanted change, which as a side effect produced exclusionary zoning. Failure of zoning in advocating intervention (change) in favor of low income groups is a significant criticism pointed out by many social and environmental justice scholars. According to Feagin (1998) there was no evidence of signific ant challenges at the level of the Supreme Court prior to the 1970s. He studied the conflicts related to planning regulations in the Supreme Court and classified these conflicts into three categories: (1) residential development for low income and minority groups, (2) environmental protection, (3) communities’ reaction against large development efforts. In several studies, residential development projects for low income groups have been disputed by “white suburban” groups (P. 194). The mechanisms of zoning preparation or modification is not efficient to reach social and environmental justice. Instead it serves class conflicts. Local governments use land use regulations and zoning to maximize and protect their revenues. In a capitalist free market, cities com pete to gain more resources and gain more profit. They offer low taxes and subsidies to attract businesses and shopping centers. From this perspective, zoning is a tool to develop land and provide guarantees for owners that their property value would be pr otected by zoning. Fischel (2008) argues that local governments act like a corporation to accumulate capital and protect it. Local governments usually do not care about regional and environmental issues. Small cities in metropolitan areas don’t have strong interests in improving the efficiency of the metropolitan structure. Most developments at edge cities contribute to car dependency, increase infrastructure costs, and degrade natural habitats. However, local governments offer greenfield sites for developm ent of shopping malls to seek more tax revenue. Zoning provides a legal power to develop suburban land, to gain surplus, and to protect use and exchange values. Lack of legal authority for regional regulation has resulted in the emergence of several self i nterested local governments with strong autonomous power in

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102 managing land use without respecting regional concerns and zoning is the main tool for implementing this failure. To understand how zoning functions as a tool, we need to understand the main deter mining factors in its policy making and review processes. From a political economic perspective, zoning influences land as an asset or capital. Therefore, the value of land, its “exchange value” and its “use value,” serve as important parameters to underst and how zoning impacts the amount of capital investment, its movement, and accumulation. Use values relate to the utility of land and property, either residential or commercial. Different social groups, for example, worker homeowners intend to protect thei r ability for continual use of the space; while real estate agencies or corporate property owners intend to protect the exchange value of their investment as a property or land. Therefore, different groups react differently against intervention in a built environment, which raises conflicts among public, local governments, and property owners. Some argue that although the goal of planning is to protect public interests and serve social and environmental justice, most mechanisms of zoning are designed to protect the use and exchange value of properties, which is contradicts public interest. From a political economic perspective, space could function as production of capitalism for accumulating capital, creating a consumption environment, and changing the sta tus of capital to gain surplus in the exchange process. However, Feagin (1998) argues that capital accumulation could relate to or happen in a space as a tool of production without the intention of producing space. In other words, space could be a side pro duction of capitalism process. Therefore, space patterns represent class conflicts and contradictions of capital. To identify the behavior of capitalist classes in space, we need to trace patterns of investment and capital mobility for gaining exchange values, because capitalist corporations seek to maximize the “constant renewal of the profit.” Changes in built environments, such as land development, subdivision, and urban renewal provide opportunities for capitalist classes to gain surplus. Feagin (1998) believes that capitalism plays an important role in decisions made particularly in CBDs and commercial centers. However, as I reviewed in the “downtown development policies” section, corporations are not the strongest player in downtowns as the land use i s being changed to public and recreational uses. If we assume that capitalism has great interests in development and built environment in urban areas and also

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103 acknowledge that downtowns are not their main territory anymore, the main question will be where the interests of capitalists class is laid now. This is still a gap in the literature of political economy. Interests of capitalism are not in the office buildings of downtowns but could be mixed use residential buildings and hospitality services. The abo ve question can be asked in another way in relation to regulations. If patterns of use and activity in downtowns are changing due to social and global trends, what kind of roles are planning and design regulations playing? This evaluation should consider t he historical background of zoning and its political economic role. Zoning: summary and criticism Zoning plays an important role in regulating developments. To understand its effects, we need to examine it in its contexts including legal supports, social a nd economic variables. Zoning implements a strong police power and follows the American Constitution. Therefore, the American governance model is directly implemented through zoning as a framework. In fact, most criticisms of zoning are related to the syst ematic problems of the governance system in the form of a liberal democratic model. The main barrier against converting zoning from an exclusionary model to inclusionary one is property rights. This constitutional right enables residences of a neighborhood to resist against any unwanted change. Although this principle has positive aspects, it creates the nimbyism issue. Parts of social segregation are, in fact, caused by this principle and zoning has been an instrument ( Glaeser and Gyourko, 2002). The lan d use segregation effect of zoning is another important criticism of zoning. This problem represents the early idea of separation of inconsistent uses such as industrial and residential uses especially when they cause nuisance. This concept was a common pr inciple in the early twentieth century among architects and planners in not only the US but also in other countries such as England. This concept also left its footprint in master and comprehensive plans. Nevertheless, modifications of zoning tended to sol ve the land use segregation problem. FBCs suggests effective solutions to promote mixed use in urban core areas. However, it seems, the principle of being loyal to the character of a neighborhood may still preserve the single use character of suburban neig hborhoods.

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104 This still leaves a legitimate question: if zoning is not an appropriate tool, then what would alternatives be? Houston, TX is a city without zoning; instead it uses Home Owner Associations (HOA) to regulate development in neighborhoods compared to other cities. In the case of Houston, the property rights principle plays a much more important role. The implementation of HOAs could also result in social exclusion and land use segregation. The growth of Houston represents a traditional liberated ma rket approach in which land use zoning is considered a violation of private property and personal liberty. From the perspective of advocacy planning, the aim of planning practice is protecting public good against private interests and in the case of Houston there is not an effective tool to protect public interests. In this context, Houston is in the hands of home owners, corporations and the market, which means there is no appropriate alternative to create a more inclusionary model. Qian (2010) explores the HOA system in Houston and argues that equity goals are not met in market approaches in this city and public planning intervention is necessary. Success or failure of zoning could not be proved by the failure of HOAs; nevertheless, we know that the HOA ci ty regulation system has its own problems and still zoning has considerable advantages. There is no doubt that zoning significantly influences urban form through regulating building envelopes (density and height), uses, and the character of building fronta ges. The evolution of zoning is tied to the history of planning practice in general and several modifications have been offered to obviate problems caused by zoning. For example, PUDs provided significant opportunities for planning through the process of r eviewing and appraisal through which unique characters and issues of place could be considered. PUDs, floating zoning, spot zoning, and other modifications shifted the focus on the process of planning rather than the outcome of planning. The major transi tion of zoning, probably, is the introduction of FBCs. Planners are watching the implementation of FBCs around the country closely to evaluate whether they can deliver a better outcome. FBCs highlight substantially the importance of form and the relationships between buildings and the public realm. To summarize how FBCs tend to improve the outcome of planning, I recognize five principles that can produce a better urban form. First, in FBCs the location of each neighborhood in cities relative to the center m atters. This means, standards regulate neighborhoods not only based on their districts but also on their relations with centers and urban structure. Second, FBCs encourage higher densities, smaller lots and buildings, and more dandified built environments. As Talen (2013) points out, the minimum lot and building sizes are considerably

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105 lower in FBCs. Third, FBCs promote mixed used buildings and neighborhoods through providing retail shops in core areas at the ground level of residential buildings. This promotes walkability and vibrancy of the public realm. Fourth, FBCs offer landscaping standards which include guidelines for planting and use of vegetation in public spaces. In addition, there are standards for the location of parking spaces (not in front of buildings) and use of vegetation for increasing permeable surface and mitigating urban heat island effect. Fifth, FBCs create continuous building frontages with regulated facades and public amenities. They also provide more enclosure through faade design gu idelines and preventing blank walls and limited setbacks. Design Guidelines Unlike zoning, design guidelines aim to regulate the details of development. From the previous section, I argued that the exact forms which traditional zoning can produce are not predictable. We can predict height and density limits, and perhaps the location of buildings in the lot but many other details and morphological variables are left vague. In commercial zones, the outcomes could be substantially disparate. This gap could da mage historical and aesthetic values specifically in old neighborhoods and downtowns. Design guidelines were used to fill this gap and regulate details of site and building planning and design. In the 1980s, when the theory and practice of urban design was progressing, several large cities adopted design guidelines to prevent unexpected shapes, in specific zones such as downtowns. Several studies were carried out reviewing the history of codes and standards including design guidelines (i.e. BenJoseph, 2005; Punter 1999; Talen, 2010; Marshal, 2011). Some of them (BenJoseph and Talen) started their historical reviews from the efforts of ancient communities in regulating any construction. In this section, I focus on design guidelines as a regulatory system st arted from 1980s to serve urban design values (with its modern definition discussed in the first part of this paper). Elliot (2008) argues that works of Christopher Alexander, particularly, and A Pattern Language (1977) have played a critical role in the u se and improvement of design guidelines as an appraisal tool. Alexander identified and classified the elements of buildings that can define their characters. He proposed a systematic method for analyzing building elements, characters, and types. Design gu idelines are supposed to reflect particularity of cities including culture, economy, climate, and the character of buildings/neighborhoods. This entails local governments design and

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106 adopt a specific set of rules. Preparing and implementing design guideline s, therefore, becomes a political process which needs effective public engagement. Punter (1999) argued that public engagement is the cornerstone of design guideline implementation. He argues that public engagement should be beyond public consultation and move toward defining design principles by the public. He found that in cities such as Portland and Seattle the public is enabled to make decisions about design guidelines. For example, in Seattle, a political consensus building effort resulted in a string comprehensive plan in 1994 aiming to accommodate growth, intensify urban areas, and provide affordable housing to achieve higher qualities through increasing neighborhood design control. He claims that implementing design led downtown development was not s uccessful because the public was not empowered and people engaged to resist powerful development interests and a powerful “City Center Development Corporation driven by tax increments provided through redevelopment” (P:196). There is always a tension betw een developers’ interests and the public interest. Environmental issues, walkability, aesthetic values, and sustainable transportation modes are examples of issues which may not be consistent with developers’ interests. For example, according to Punter (1999) public revolts against some strategies of downtown development plans in Seattle (1984) and San Francisco (1985) led some modifications to address public concerns. In the ongoing challenge between developers and citizens, only strong public participation frameworks can serve a better balance. Local governments can conduct education programs to raise planning literacy and encourage activism efforts to resist against corporations’ interests. Design guidelines need a legal back up and also should be clear, meaningful, and easy to understand. Also, from legal a perspective, design guidelines should be predictable because courts follow “no surprise” principle in case of conflicts. Design guidelines can be accommodated in zoning and implement its standards through a zoning regulatory system. Vague rules can raise conflicts between local governments and developers/owners. Courts do not accept arguments such as “incompatible” or “non harmonious” developments to reject an application. Punter (1999) argues that cour ts consider such terms and rationales as not properly researched or vague policies. For example, in a court in Washington State, a permit refusal by the city was rejected in the case Anderson v. Issaguash because of not clear standards and rules of zoning.

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107 Those cities with strong design guidelines and regulations have been successful in embedding details of land use, activity, form, and buildings. However, preparing such comprehensive rules needs significant funding and time. Even cities with great plans are not able to revise and update them. New analyses and tools could improve plans through an evidence based process. Design guidelines were designed to cover shortcomings of zoning in regulating actual shape and character of buildings in their neighborhood contexts. They could also override zoning rules by providing some qualities or specifications. Talen (2009) claimed that design guidelines are advisory. However, I believe Talen’s argument is not accurate in all cities. Sometimes design guidelines are adopted as regulations which are not less important than zoning. Developers have to follow these rules, otherwise their applications could be rejected. Punter (1999) studied five major cities and showed how design guidelines play an important role in shaping special districts, downtowns, and PUDs. Nevertheless, there is no consistency among the design guidelines adopted by different cities. In some cases, design guidelines remain very brief and peripheral. Also, Punter does not provide a clear explanation of the relation between zoning and design guidelines. There are questions that I could not find appropriate answers for in the literature: What type of shortcomings does zoning have that design controls could resolve? How do design guidelines address climate adaptation and mitigation strategies (especially urban heat mitigation)? To summarize, design guidelines provide a great opportunity for controlling design details and microclimate variables. Design guidelines are customized regulations for downtowns or s pecific areas and as a result they can potentially guarantee some qualities. Cities can improve public space qualities with detailed design guidelines. Design control is a process rather than a product and should be revised based on new issues, paradigms, and needs. Similar to performance zoning codes, design guidelines could rely on the consequence of a development or a project. For example, as the shape of buildings are important, the solar reflection of their facades and overshadowing issues could be controlled under some quantified standards. In other words, design guidelines are a good framework to connect general goals and objectives to quantitative measures and standards.

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108 Planning procedures At the same time, procedural and political factors are als o critical components of local regulatory systems. Recent discussions in planning theory have addressed the process of decision making in a democratic context. These conversations are mostly focused on social justice discourse and whether “democratic” procedures can produce “just outcomes” (Healey 2003) or how the endemic, inherent imperfection of democratic processes does not inevitably lead to a just outcome (Fainstein 2010) . The complications may include imbalanced power relationships, domination of public engagement by privileg ed groups (Healey 2003) , conflicts of interest (Campbell 1996) , local economic drivers (Harvey 2010) , quality of discretionary review processes (Nasar and Grannis 1999) , and character of redevelopment teams (i.e. owners, investors, developers, consultants) (Stevens 2010) . Healey (1997) shows how variations of norms and principles can produce different processes and outcomes in planning. At the same time, Fainstein (2010) advocates for focus on ensuring a ‘just outcome’. She suggests a more direct intervention in circumstances where the procedure can potentially fail. The failure in achieving main goals is a pro duct of various conflicts in the process of planning. The nature of conflicts in the planning process is well theorized. However, there are less studies exploring how conflicts impact the management of major developments and more specifically the way confl icts can potentially hinder planners in achieving environmental values. In this paper, we examine two local regulatory environments, including both institutional and procedural contexts, to assess how their decisionmaking processes affected microclimate outcomes as an example of a complex urban system in the context of climate change. Urban Heat Island Mitigation in Policy Documents Urban heat island mitigation Most of the available literature about urban heat mitigation is focused on increasing the albed o of urban surfaces including roofs and pavements through using light colors and high albedo materials. Other widely proposed solutions have been urban forestry or planting vegetation. Akbari and Huang (1987) studied the potential of vegetation in reducing the use of summer time cooling systems in residential buildings. This research shed light into the ways landscaping impacts the microclimate of cities and as a result energy consumption.

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109 Rosenfeld et al (1995) reviewed the mitigation programs in Florida and California. They suggested that any heat mitigation program needs (1) to run test procedures for cool materials, (2) to assemble cool materials databases to guide and support the building development industry, architects, industries, and developers, (3) to incorporate cool roofs and tree canopies to build energy performance codes and other amendments, (4) and to offer incentives to complement standards and codes. They also measured the impact of cool roofs and higher albedo roof colors in reducing energ y consumption. Their experimental studies in California and Florida showed that cool roofs can reduce the energy use by 20 40%. Rosenfeld et al (1995) enumerated a number of policy programs that could encompass heat mitigation policies. Bretz et al (1997) studied Sacramento, California. They estimated that about 20% of the buildings and 10% of roofs have low albedo. They estimated that if the albedo of these surfaces were elevated, the overall albedo of Sacramento city could be raised by 18%. This improveme nt in albedo could produce a significant saving (about 10%) in energy consumption. Rosenfeld et al (1998) argued that in Los Angeles, the annual residential air conditioning bills can be reduced by about $100 M through adopting strategies such as increasi ng the albedo of surfaces and planting shade trees. They argued that this saving results in the reduction of emission and consequently smog in Los Angeles’ weather, which benefits the city indirectly. They estimated the indirect benefit could be about $360M. Takebayashi and Moriyama (2007) study some variables including the surface temperature, radiation, water content ratio, etc., in relation to green roofs and high albedo roofs. After comparing different surface types, they find that on a surface with hig h albedo (white paint), the sensible heat flux is small because of the low net radiation (most portion of the shortwave radiation is reflected back to the sky). On the green surface, the sensible heat flux is small because of the large latent heat flux (th rough evaporation) although the net radiation is large. This study, through a numerical modeling, shows that high albedo and water contents can significantly reduce urban heat and should be addressed in mitigation policies. Akbari and Rose (2007) studied f our major US metropolitan areas at high resolution to measure the surface type precisely. They examine the land use and land cover types in urban areas and find that about 2941% of the area is covered by vegetation, 1925% is covered by buildings, and 2939% is covered by paved surfaces. They find these surfaces a potential area of change and

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110 suggested planting vegetation and increasing the albedo of surfaces as some viable solutions for mitigating urban heat. EPA (2008) summarizes that vegetation and gree n/cool roofs are the main heat mitigation strategies considered by standards and policies. However, they mention heat mitigation through modifying urban geometry could be a potential area that has not been considered well. Memon et al (2008) carry out a r eview study and summarized the proposed strategies for heat mitigation. They also study the potential temperature reduction and energy saving. Again, they focus on increasing albedo and vegetation as the main strategies. Urban geometry and morphology is not among the variables they reviewed ( Table 8). Table 12: Proposed mitigation strategies, maximum potential temperature reduction, and possible energy savings It is evident that urban mitigation policies are highly focused on albedo and vegetation. Although there has been good research identifying the role of urban geometry on forming urban heat island effect, most studies have ignored the influence of urban morphology in heat mitigation. One reason could be related to easier process of increasing roof albedo or planting vegetation compared to modifying urban form and morphology needs a long term plan and raises highly

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111 complicated policy issues. Another reason could be that most of these st udies are coming from engineering or environmental study disciplines and the planning dimension is very weak. Planners need to study the role of policy and space making in heat mitigation. Urban heat island mitigation in policy documents in Denver As discu ssed in the previous section, most mitigation strategies were focused on increasing vegetation and surface albedo. This is also a visible track in policy documents. As urban heat mitigation is a relatively new issue, in most planning and design policies th ere is no direct attention or intention to address the urban heat issue. In recent years, adaptation and mitigation plans or climate action plans (which are mostly advisory not mandatory) are raising the urban heat issue. In this section, I briefly review the climate adaptation and mitigation plans. The City of Denver prepared its first Climate Action Plan in 2007 which was mostly about reducing GHGs. In 2014, a new Climate Adaption Plan was published. Contrary to other cities’ climate action plans, an incr ease in temperature caused by the urban heat island effect is one of the main concerns of this plan. This plan also has addressed the possibility of extreme heat events in the Denver Metro area. In that report, the literature of urban heat island and extreme heat events is reviewed with the support of some evidence in the region ( Table 9). However, in the proposed strategies urban heat island mitigation is limited to “Reduce urban heat island effect through infrastructure such as shade trees, urban gardens, green roofs, and lighter colored hardscapes” (City and County of Denver, 2014, P:75). These tasks are assigned to Department of Public Works (DPW). Denver’s climate action plan suggests that building codes should address issues related to roof colors and materials issue. Other suggestions are related to adaptation of extreme heat events. For example, the plan suggests a weather advisory and notification system to notify high risk population. They also suggest prepa ration strategies for emergency services, urban infrastructure, public cooling shelters, and education. Denver Climate Action (2014) also suggests some mitigation strategies including: Preparation of a tree and shade master plan, Offering a list of approv ed trees for planting in public realms, Preparation of storm drainage master plan, Promoting the energy efficiency of buildings and reducing anthropogenic heat,

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112 Installing high albedo hardscape when resurfacing roads, multi use paths, and city parking lots , and identify life cycle costs associated with concrete vs. asphalt, Requiring permeable pavement for a portion of parking lots larger than one acre, and Integrating climate change into planning and zoning considerations. Overall, the Climate Action Plan (2014) proposes some good strategies and directions. However, this plan needs to translate to codes and policies that could change the general planning and design practice. It seems the distance between setting appropriate goals and objectives and policy t ools is not filled yet. One of the main strategies of this plan was “integrating climate change into planning and zoning considerations.” The latest zoning which was adopted in 2010 suggests promotion of urban vegetation but still does not force heat mitig ation in practice. Comparing the climate action plans for Boston (2014), Los Angeles (2012), and Denver (2014) reveals that Denver has taken a very progressive approach in paying attention to urban heat island effects and heat waves. Denver proposes some significant strategies and objectives which are consistent with the current literature. Los Angeles and Boston do not even consider urban heat mitigations in their plans. Although Denver’s plan is a considerable move in identifying and addressing the urban heat issue, there is a gap between high level goals and objectives and policies. Table 13: Priority Climate Change Vulnerabilities in the Denver Metro Area (City and County of Denver, 2014)

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113 Urban Heat Related Policies: We can categorize all policies that could influence urban microclimate into two classes: (1) policies designed specifically for urban heat mitigation, (2) policies designed for other purposes but capable of influencing urban microclimates. Among all American citie s there a few that have some policies purposely designed to mitigate heat. In this section I will review the codes and ordinances of some cities that have detailed design guidelines related to heat mitigation. All other policies that I reviewed in this sec tion could be classified in the second class. For example, zoning, subdivision, and design guidelines regulate some form elements of cities, influencing urban microclimates. As the main subject of my dissertation, I will explore these policies to unfold th e

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114 ways form changes microclimate of cities. In this section of literature review, I focus on policies designed specifically to improve urban microclimates and I briefly bring some examples from other policies designed for a purpose other than heat mitigati on. Microclimate related policies in Chicago I chose to review policies in Chicago because the great heat wave of 1995, which caused more than 500 mortalities, attracted more attention to the urban heat island subject at policy levels. In chapter 18 of the building code which is about energy conservation, there is a section dedicated to design criteria that mitigate urban heat islands. This section focuses on buildings, their roofs, materials, energy efficiency, and facades. The regulations enforced in thi s section are mostly designed to increase radiation reflectance. “All roof exterior surfaces shall have a minimum solar reflectance as specified in 18 13303.2.1 through 1813303.2.3 when tested in accordance with ASTM E903, ASTM E 1918 or by testing with a portable reflectometer at near ambient conditions. 1813303.2.1 Low sloped roofs: Roofing materials used in roofs with slopes of 0 in 12 to 2 in 12 shall meet the following requirements: Any roof installed pursuant to a building permit application submitted before April 22, 2009 shall have a minimum initial solar reflectance of 0.25. (Amend. Coun. J. 9104, p. 30857, 1; Amend Coun. J. 11508, p. 45090, 1) 1813303.2.2 Medium sloped roofs: Roof materials used in roofs with slopes of over 2 in 12 and up to and including 5 in 12 shall, beginning 1/01/05, have an initial solar reflectance of 0.15 or greater” (City of Chicago, 2009, P: 15). In this code, there are very specific rules for building and roof insulations which can potentially reduce energ y consumption and consequently can mitigate anthropogenic heat flux in the urban energy balance. Also, there are regulations about controlling the glare of facades and preventing them from reflecting solar radiation. In the use regulations of zoning ordinance (chapter9) there are some criteria that prevent nuisances. For example, in section 7 of this chapter in relation to commercial uses, it is stated that:

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115 A business live/work unit shall not be established or used in conjunction with any of the following activities: “Any other activity or use as determined by the Zoning Administrator to not be compatible with residential activities and/or to have the possibility of affecting the health or safety of business live/work unit residents, because of the potenti al for the use to create dust, glare, heat, noise, noxious gasses, odor, smoke, traffic, vibration or other impacts, or would be hazardous because of materials, processes, products, or wastes”. Although this rule is not directly designed to mitigate heat, regulating glare and heat could contribute to heat island mitigation. However, the regulations do not define “glare” and “heat” precisely. In the landscaping regulation section (1710) of the zoning ordinance, there are some clear guidelines about planting trees and vegetation. For example, “One tree must be planted for each 125 square feet of required interior landscape area”. Also parking lots with the area of 30004500 SF need planting tree canopies equal to five percent of the total parking area. Parkin g lots with the area of 450030000 SF need to be covered by tree canopies as much as 7.5 percent of the total area of the lot. These rules can reduce the urban heat mitigation to some extent because parking lots are one of the significant radiation absorbe rs in cities. However, the City of Chicago has adopted several plans and strategies to promote sustainable development. These plans target improving vegetation and storm water management systems. For example, in 2008, the City of Chicago prepared a comprehensive plan named “Adding Green to the Urban Design”. This plan suggests a wide range of strategies to promote storm water management and urban vegetation. This plans suggests methods to convert impervious surfaces to permeable surfaces. There are some spe cific objectives offered to mitigate urban heat island through vegetation, green roofs, water management, urban forestry, etc. However, this is an advisory plan not an enforced one. The Chicago Green Alley Handbook, also, is a detailed guideline for promot ing urban vegetation and sustainable storm water management. This plan is also very similar to the previous one. These efforts are strongly consistent with urban heat mitigation strategies and were designed to improve water and air quality which includes u rban heat mitigation solutions as well. Microclimate related policies in Phoenix, Arizona

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116 Phoenix is located in a hot and arid climate. Phoenix has been the case study of many urban heat island studies. Therefore, there is a good knowledge about the natur e of urban heat island in this city in the literature. Reviewing the policies and codes adopted by the City of Phoenix shows that there is a strong dimension related to urban heat island mitigation. In 2002, in a general plan titled Environmental Planning , an urban heat island is considered as a central issue. Urban heat island mitigation is one of the main goals in this strategic plan. Although this plan could guide some detailed guidelines in next steps, it remains as an advisory policy document. Some ge neral objectives are recommended (City of Phoenix, 2002, P: 271): 1. “Study options for building materials and paving surfaces that minimize the absorption of heat. Recommendations: a) Study and explore options to increase shade canopy, by developing street des ign standards to increase the number of trees planted along all new public streets. b) Retrofit existing streets where possible, to increase the shade canopy along each side of the street for both pedestrians and vehicles. c) Encourage the use of light colored building and roofing materials on municipal, commercial, industrial, and multiunit residential structures. Consider a recommended standard for solar reflectivity for roof systems. d) Research alternative paving materials that absorb less heat. E. Explore metho ds for restricting the use of reflective glass on commercial properties above the second floor, whenever the commercial structure is adjacent to a residential area. e) Consider amended street cross sections, which decrease the amount of paving required. 2. Encourage the planting of mature trees (and other vegetation) as a method to provide shade and help reduce temperatures. a) A. Study an ordinance change that would require public and private development to plant and maintain an adequate number of trees that will achieve 50 percent shading on parking lots and the nonbuilding portion of a site in 15 years..

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117 b) Encourage constructing medians with size appropriate shrubs and trees in new streets of four or more lanes. c) Encourage shaded open space in private development to reduce heat impacts. d) Develop a program to educate the public regarding the heat island effect. e) Explore developing a citywide program to promote tree planting as a method to help reduce the urban heat island effect. Another important policy document that has a strong urban heat mitigation dimension is Downtown Phoenix Urban Form Project. This plan, which was adopted in 2008, is a policy document “designed to provide directions as work continued on the Form Based Code. This effort resulted in the Downt own Code which was adopted by City Council in 2010 and is now Chapter 12 of the Zoning Ordinance”. In this plan there is significant attention to shading to mitigate urban heat: “The need for shade in the pedestrian environment, and the need to design for longterm environmental sustainability is critical. Concerns were expressed about the ability to make Downtown comfortable during hot weather months, and the need to minimize the Urban Heat Island effect. Chapter 2, presents detailed guidelines to ensure s hade, create comfortable temperatures for pedestrians, and minimize the UHI” (City of Phoenix, 2008, P: 111). Increasing the density of the city and specifically the density of downtown has been one of the strategies to mitigate urban heat island effect: “Cooling the Urban Heat Island Effect. Build compact highdensity development in Downtown so that other land in the Phoenix region remains undeveloped and mitigates rising regional temperatures. Construct buildings, streets, and public spaces in Downtown t o minimize the Urban Heat Island effect” (City of Phoenix, 2008, P: 115). Chapter 4 of this policy document is dedicated to the urban heat island issue. This chapter explains the science of urban heat island and its effects. Several strategies of heat mi tigation are reviewed and introduced in this plan including: Optimizing street canyon proportions for shade, sky view and air flow (deep urban canyons that could direct and canalize wind are encouraged,

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118 Building form optimization and proposed massing standards (using a good combination of open space and building mass to produce shadow and distribute open space). Given the assumptions and simulations noted above, the Urban Form Project is proposing the following building massing, street wall and open space g uidelines for high rise commercial and residential districts should be considered when developing urban form standards: I. Maximum lot coverage of 8090% (or 10 20% open space) not including alleys II. Building base not to exceed of 8 stories or 90’ III. Building projections of 10’ permitted in the right of way (creates effective street canyon proportion of 1:1.5) IV. Maximum lot coverage of 50% above 8 story base V. Towers to be located a diagonally opposite corners VI. The average street canyon proportion is not to exceed 1:2 – measured over the entire block (average of base and tower) VII. Minimize building sections to encourage natural ventilation Supplemental shading (“the proposed street canyon proportions provide a minimum amount of shading coverage and must be supplemented by additional pedestrian level shading on all street sides. This additional layer of shade shields pedestrians from the reflected light and long wave radiation from the structures above. The presence of a shade canopy (natural or architectural) also diminishes the amount of heat absorbed by the sidewalk and helps in the mitigation of UHI”) (City of Phoenix, 2008, P: 416). Building materials (lighter colored materials with a relative low density are suggested because they are more efficient in reflecting radia nt energy from the sun) Cool pockets (distributing areas of concentrated shading and cooling through the urban fabric)

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119 This policy document summarizes the strategies and solutions of urban heat mitigation through suggesting a series of policies. These policies ( Fi gure 36 Proposed Building Massing (Phoenix, 2008)

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120 Table 14), in fact, are some objectives that need to be translated to actual code and standards. In other words, although this document offers some fairly detailed solutions, it still remains genera l and advisory.

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121 Table 14: Urban Heat Mitigation Policies Proposed in the Downtown Development Project (City of Phoenix, 2008) 1) Adopt thermal comfort and sustainability standards for building form in Downtown to optimize thermal co mfort, minimize heat gain, and enhance air flow. 2) Encourage 50 percent of the south facing building wall adjacent to streets, sidewalks, and public spaces to be shaded at solar noon on the summer solstice. 3) Prepare development standards for ground level sh ade. 4) Encourage the location of buildings and shade structures to maximize shade over road intersections and mid block pedestrian crossings over major streets. 5) Construct shading materials for trellises and canopies of low mass, non conductive materials. 6) Prepare a development standard requiring 50 percent of habitable roof areas, including parking decks, to be shaded with trees, trellis vines, photovoltaic panels, or a combination thereof. 7) Prepare development standards for roofing materials to reduce heat gain using the Standard Reflectivity Index (SRI) 8) Consider establishing standards for the use of permeable paving materials for public and private develop. 9) Prepare development standards requiring construction using wall materials with high levels of refl ectivity and emissivity with smooth surfaces and the ability emit heat to the surrounding environment. 10) Provide development standards that require a minimum of 50 percent shade in publicly accessible plazas, courtyards, and other public spaces (publicly o r privately owned).Shade from adjacent buildings or structures can be counted towards the total. A minimum of 25 percent of the shaded area should be trees or trellis vines. 11) Encourage a minimum 30 percent continuous live vegetative ground cover in public spaces larger than 5,000 square feet. 12) Consider including a water feature in public spaces such as courtyards or plazas. Design water features to optimize thermal comfort by wetting large surfaces and introducing moisture into the air through sprays or in termittent jets. Water features shall be located in semi enclosed areas to contain cool air. 13) Encourage green walls to reduce excessive radiant heat accumulation in pedestrian areas receiving excessive sunlight.

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122 Figure 37 Buil ding Frontage Regulations from the Design Guidelines of Downtown Belmar, Lakewood, CO Conclusion of planning and design policy section: In this paper, first, I reviewed design theories and new directions in urban design, urban renewal, and downtown development policies. Then, I reviewed different urban policies that shape urban built environments. I reviewed codes and standards of regulating urban form, subdivision regulations, zoning, and design guidelines. The core issues reviewed in this paper are zoning and design guidelines that are the main tools of regulating planning and design. In both literature review papers (microclimate and policy), I provided a precise picture of available literature in relation to current policies shaping urban built environm ents and the ways built environments influence microclimate. Development control and urban form regulatory systems are supposed to protect the natural environment and to restore social justice through advocating interests of vulnerable groups. It is

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123 evide nt that human interventions have driven climate change and global warming at local scales as well as global scales. The consequences of climate change affect low income and vulnerable groups the most. Therefore, it is essential for planners and designers t o identify the climate related issues, develop some feasible adaptation/mitigation strategies, and readdress the environmental and social justice issues with a fresh perspective. Most environmental issues such as water quality, air pollution, flood, habit ats, endangered species, and forests have been addressed through strong policy frameworks. In each case, researchers have shown the importance of the issue and the role of human activities. Urban microclimate and more specifically urban heat is a relativel y new and unknown issue. Therefore, understanding the scientific mechanism becomes an important step to direct policies for mitigating and adapting related problems. In urban areas, we already have created a strong regulatory policy framework to guarantee quality of life and sustainability. Although zoning has its own flaws, it is still a significant police power that enables planners to leash market forces (to some extent) and to create walkable and vibrant public spaces. As I reviewed, planning scholars have identified some side effects of zoning such as inflexibility, increasing housing prices, and exclusionary effects. Reviewing case studies and evidence show that land use and zoning regulations could produce completely different outcomes than planners’ goals. The efficiency of tools depends on the context, the implementation process, and their principles or approaches. In short, not only the types of regulations are important, but also the approaches they use, the groups they target, and the problems they focus on, which could produce good or bad outcomes. In my dissertation, I am interested to explore how different approaches in utilizing zoning and design guidelines in the development of downtown and commercial areas could make a significant differenc e in their microclimates. Reviewing adaptation and mitigation policies in multiple cities show that except for some general strategies, there is not any specific policy intending to mitigate urban heat. The current available policies remain as advisory str ategies without developing specific details to implement them. The literature review of policies and urban microclimate show that there is a significant gap in the practice of planning to translate general heat mitigating strategies to codes and standards. However, there are some codes and guidelines that are designed for a different purpose but could potentially mitigate urban heat. In this research, I will explore the

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124 potential effects of indirect policies in heat mitigation. I will scrutinize zoning and design guidelines to find which aspects or parts could mitigate or exacerbate heat effects in downtown and commercial areas.

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125 III. CHAPTER 3: METHODS Research aim, objectives, and questions Research aim This research goal is to explore how urban development policies –in particu lar, zoning and design guidelines – can create an urban morphology that is more effective for heat mitigation in cities. In fact, my broader aim is to introduce a method for evaluating design strategies and related poli cies in the context of environmental and climate related issues. My proposition in this research is that, in addition to other variables, policy and planning and design regulations shape the built environment. These factors can potentially affect microclimates of urban areas . Thus, my main focus becomes measuring whether certain policy approaches or variables affecting the implementation processes can significantly change the microclimate outcomes of urban areas. My previous research, pilot study, and literature review show t hat certain elements of urban form, including building envelope, vegetation, and street patterns, are capable of causing considerable microclimate variations. Given this preliminary knowledge about the relationships among policies, form elements, and urban microclimate, I am interested in exploring the exact mechanisms of these relations to propose specific policy modifications targeting effective heat mitigation in the context of a changing climate. To explore the interconnectivity of these variables, I ch ose two case studies in the Denver metropolitan area that have been recently redeveloped in an urban renewal framework to create walkable and vibrant urban spaces. Later in this chapter, I will explain why and how I selected these two sites to carry out my research. Research objectives 1. To examine the extent to which urban form can be modified to deliver a better (cooler) microclimate ( particularly i n hot and arid regions) while satisfying sustainable development principles , such as compactness and walkabili ty; and 2. To understand the policy making and implementation processes through which urban form could be regulated in relation to urban microclimate.

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126 Research questions To address these objectives, this dissertation has two main and one subsidiary research questions: 1. To what extent do planning policies improve or degrade urban microclimate? Comparing form based codes and conventional zoning as two different approaches, which one can provide a better foundation for adopting heat mitigation strategies? 2. In what ways do planning procedures (particularly the design review process) influence the implementation of policies with respect to microclimate outcomes of redevelopment projects?

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127 Research Design I structured this dissertation in two components. The c omponents are (1) urban microclimate and policy simulation and (2) analysis of regulations and their implementation procedure s . I used a hybrid research design. For the first component, I used an empirical research design. This component takes the built form variables (building form, street form, surface types, tree density and type) and simulates microclimate variables (e.g. wind speed, wind direction, ambient temperature, and mean radiant temperature) in the first step. In the second step of the first com ponent, I build various policy scenarios to explore the relationships between form and policy. To develop these scenarios, the main policies of each site were targeted. I chose building height, tree density, and street directions as some variables that would be potentially important according to urban microclimate literature. Assuming that the form is the outcome of policies, I switched the main policies of the sites to examine how policy changes can affect microclimate variables. To assess the impact of po licies on microclimate and compare the two study sites, I developed four policy scenarios in addition to the existing situation . The scenarios address the differences in policies that generated the different built forms in Belmar versus the 29th Street Mal l. The variables I used to build the scenarios include: ( 1) building height, ( 2 ) street directions, ( 3) tree density, and ( 4 ) a combination of all ( Figure 49). The second component of the dissertation uses a case study design to explore the contents of policies and their pertinent context in which they were implemented. Figure 38 shows the conceptual model of the dissertation and the ways each component connects the variables. Urban microclimate is the de pendent variable of this dissertation. The main independent variable is planning regulations and policies; however, to understand how policies affect urban microclimate, urban form is used as an intermediate variable. In other words, planning policies shape urban form and then urban form impacts microclimate. It should be noted here that the relationships between form and microclimate can be scientifically examined. However, the relationships between policy and form is more indirect and needs an indepth qualitative study. As Figure 38 presents, the relationship between urban form elements and urban microclimate needs to be studied first to be able to start the second component which is the relationship between planning policies and urban form elements.

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128 Figure 38 Dissertation conceptual model and components Case studies I chose two recent urban redevelopment projects developed located in the Denver metropolitan area: (1) Belmar in downtown Lakewood, CO and (2) 29th Street Mall in Boulder, CO. Prior to redevelopment t he sites had similar histories. Both were indoor shopping malls developed in the 1960s, surrounded by parking lots. In the mid1990s they experienced declin ing sales, and in the early 2000s the decision was made to redevelop them . The historical shopping mall in Lakewood was Villa Italia, demolished in 2002 to develop Belmar as a new mixeduse urban center. The Crossroads Mall in Boulder was demolished in 2004 and redeveloped as the 29th Str eet Mall , which opened in 2006. Figure 39 a nd Figure 41 show before and after redevelopment of the sites. The two malls also operate in different political and economic environments, which may influence p lanning outcomes. H ousing prices in both communities have increased significantly over the past decade, but Lakewood has considerably lower incomes and real estate values . Lakewood’s median household income is $76,000 per year compared to Bo ulder at $91,000 (Census Bureau 2015) . Its m edian housing value is $350,000 compared to $650,000 in Boulder (Zillow, Inc 2017) . Boulder was a popular destination for real estate invest ors even during recession years and has experienced a high rate of business development . Lakewood, in contrast, experienced lower rates of business growth over the past decade. Table 15 summarizes policies and characteristics of both sites. Belmar Belmar is a mixed use renova tion and redevelopment of on old almost abandoned indoor shopping mall, Villa Italia, surrounded by asphalt parking lots in Lakewood, Colorado ( Figure 39). Planning and Design Policies Urban Form Elements Urban Microclimate First Component Second Component

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129 The site covers 23 city blocks (104 acres). Villa Italia opened in 1966, but its popularity declined over time and by the mid 1990s, most of the stores were empty in 1999. Before redevelopment could take place, the mall site required cleanup of soil contaminated over the years with perchloroethylene (PCE) from two dry cleaning b usinesses located in the mall. (EPA, 2009). The $850 million project began to take shape 14 years ago when thenMayor Steve Burkholder appointed a citizen's advisory committee to guide the redevelopment of the Villa Italia Mall. Since opening, Belmar prope rty values have increased 700 percent from 2004 to 2012. In the Alameda corridor, property values increased 36 percent from 2001 to 2013 (The Denver Post, 2014). Figure 40 shows the Primary site plan. Belmar has been zoned as PD (Planned Development) and M G U (Mixed General Urban). PD8 is the same as PUD (Planned Unit Development) zone, which is an overlay zone on top of M G U9. As a result of PD, the City of Lakewood required a comprehensive site plan which is consistent with Mi xed General Urban regulations. 8 According to the zoning ordinance of Lakewood, “the Planned Development (PD) district is intended to permit the planni ng and development of substantial parcels of land which are suitable in location and character for the uses proposed and are suitable to be developed as a unified and integrated project in accordance with detailed development plans” (City of Lakewood, 2014, P:64) 9 According to the zoning ordinance document, Mixed General Urban district “is intended to provide for mixeduse and community commercial development generally along arterial streets and in transit areas. The Urban context reflects a more pedestrian oriented environment that requires buildings to be located within a short distance of adjacent public streets. Parking shall be located behind or to the side of buildings” (City of Lakewood, 2014 b, P: 1).

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130 Figure 39: Aerial Photo of Belmar before (left image, 1999) and after (right image 2014) (Captured from Google) Figure 40 Belmar Site Plan of the redevelopment project 29 th Street Mall (Boulder, CO) This site is not located in downtown but was developed to create a mixeduse commercial area. Similar to Belmar, 29th Street Mall was developed in the place of an old declining indoor mall, Crossroads Mall. Crossroads Mall wa s built in 1963 with 394,000 leasable square feet for retail stores, surrounded by parking lots. Since the mid1990s, the mall started to decline due to construction of some other regional shopping centers in this region. In October 1997, the vacancy rate at Crossroads was 19%. The Mall closed in February 2004 and was demolished shortly after

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131 its closure. I n 2006, the Twenty Ninth Street retail district opened. 29th Street Mall is zoned as BR 1, which is Business Regional 1. In the zoning document of city of Boulder, BR 1 is defined as “business centers of the Boulder Valley, containing a wide range of retail and commercial operations, including the largest regional scale businesses, which serve outlying residential development; and where the goals of the B oulder Urban Renewal Plan are implemented” (City of Boulder, 2007). According to the zoning ordinance of Boulder, this site has been part of the Boulder Urban Renewal Plan. In other words, the City of Boulder has considered this site as an opportunity for urban renewal for improving mixeduse patterns and walkability. Figure 41 Aerial Photo of 29th Street Mall before (left image, 2002) and after (right image 2014) (Captured from Google)

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132 Table 15 Case stu dies Criteria Belmar (Lakewood, CO) 29 th Street Mall (Boulder, CO) Planning Approach Urban Renewal; New Urbanism; Form Based Code Urban Renewal; Mixed Use; Walkability Main policy Zoning, Design guidelines Zoning, Design guidelines Zoning type PUD M G U Business Regional1 (BR 1) Design guidelines Y es Yes Land use combination Townhouses, Apartments, Restaurants Commercial retailers Commercial Retailers One Residential Building, Restaurants Building types Elevation 5500 ft 5285 ft Latitude

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133 Component 1: Microclimate Simulation Building from these two case studies, t he first main question is addressed using an explanatory framework to explore a causal relationship between urban form variables (elements) and microclimate variable s. To answer this question, I used an experimental research design. The key point in doing so is controlling the context to extract independent and dependent variables for measuring causal relationships. However, uniqueness of regional climate makes this r esearch dependent on the context and limits its generalizability. Through developing multiple policy scenarios, I controlled the context variable s to detect the causal relationships between the independent and dependent variables. The core analytical part of this component is urban microclimate simulations for which I used ENVI met software. ENVI met is a holistic microclimate model that uses high resolution three dimensi0onal built environment configurations (input model). ENVI met calculates most urban en ergy heat fluxes (introduced in the literature review chapter) based on fundamental laws of fluid dynamics and thermodynamics . The input model of ENVI met needs three dimensional building configurations, surface plant types, tree location and species, impervious surfaces and their types (asphalt, concreate, etc.), and permeable surface types (soil types). The simulation, also, requires a set of meteorological variables as the initiation values. Data collection for the experimental phase: The first component of this research uses an experimental research design to investigate the relationships between urban form elements and microclimate. In this phase, I explore causal relationships that are based on scientific rules. The data that is used in this phase have fed the simulation models and their validation process. I build a three dimensional model of each site including building envelopes, vegetation type and density (distribution), and surface type including asphalt, concrete, and permeable surfaces. The dat a for these models are derived from GIS datasets available from local governments. Vegetation and soil/surface type data are collected through surveying the site. All data is digitized and converted to GIS vector formats. The 3D models were converted to EN VI met input area format. To run simulation models, first, a date should be chosen to imitate the model with some meteorological data such as cloud cover, precipitation, humidity, and temperature variations of the regional climate. After running the model, the results should be

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134 validated with the data collected at the site level. The following section will explain how the local data is collected for both choosing an appropriate day and validating the model results. Data collection at the site level: To choose an appropriate day and to validate the results of simulations and models, I collected ambient temperature and relative humidity to examine the accuracy of microclimate simulations at the site level. To collect ambient temperature , I use d a temperaturehumidity data logger ( Figure 42 ). This data logger is produced by LabJack company . The specifications of LabJack data loggers are summarized in Table 16. I use d this instrument to collect data in the sites in 10minute interval s . The data logger has a transparent, waterproof (from top side), and vented (from bottom side) enclosure to protect the instrument and to collect light, temperature, and humidity. Table 16 Technical specifi cations of LabJack TLH Memory 260,000 Readings Logging intervals 10s, 30s, 1m, 10m, 30m, 1h, 6h Temperature accuracy @ 70F 0.2(0.1) to 0.5(0.3) F(C) Battery life 3.3 Years @ 25C and 1m logging rate Battery type 3V CR1632 coin cell, replaceable So ftware Free, Windows only Communication USB Real time clock 2 seconds per day @ 25C Memory Wrap No Single/Multi Use Multi use Conformal Coating Yes Operating Temperature 35C to +85C ( 31F to +185F) Waterproof Enclosure (TL) Yes, IP68 Vented Enclosure (H) IP53

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135 Figure 42 Temperature/Light/Humidity (TLH) Data Logger Produced by LabJack Locating data loggers: I distribute d about 12 data loggers in two sites to collect high temporal and spatial resolution ambient temp erature. I located 6 data loggers in each site and tagged each data logger with a unique number and tried to locate them in similar environmental settings ( Figure 43). Figure 4 3 : Tagged data loggers rea dy to be located in the field

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136 All data loggers were attached to the north facing walls of buildings to avoid direct radiation. Finding appropriate locations was a challenge in commercial areas. First, most buildings and the site managers do not allow any a ttachment to walls. Second, given the height of data loggers needs to be about two meters above ground, they are in plain sight and can be easily removed. All data loggers were attached in locations that are not influenced by trees or permeable surfaces. D ata loggers collected data from June 6th, 2015 until July 3rd 2015. Figure 44 shows the distribution of data loggers in each site. Figure 45 shows the context and location of some data loggers in their environment. The temperature data collection process had some complications. First, finding a relatively safe location that meets all requirements to collect valid data was difficult, and therefore I compromised some of the cl imatic criteria in exchange for a good location to attach the data loggers. For example, at 29th Street Mall the property manager of the site did not collaborate in finding appropriate and safe locations. Instead I worked with individual businesses to atta ch the data loggers and as a result, their heights vary. Second, four of the data loggers were lost out of 12 that were deployed. Figure 44 L ocation of d ata l oggers in the site maps (red circles )

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137 Figure 45: Loction of data loggers Site models: To simulate urban microclimate, I used ENVI met V. 4 software. ENVI met needs a three dimensional gridded model domain including: (1) building envelope (footprint and height), (2) location and species of trees o r surface vegetation, (3) surface material, and (4) soil type for permeable surfaces. I chose a 250 x 250 x 30 grid with 2meter cell size as the resolution of the input files. Input data are collected through field surveys and from GIS datasets made avail able by local governments. I used LiDAR data to create a Normalized Digital Surface Model (NDSM) layer to measure the heights of buildings and tree canopies. The impervious surface dataset

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138 provided by the City of Denver was used for mapping impervious and permeable surfaces. The surface materials, soil type, tree species, and other details were collected through field observations. All layers were digitized and converted to GIS vector formats and then converted to raster layers with 2 meter cell size. I cr eated a geoprocessing procedure to generate the ENVI met input files automatically using GIS. I exported each raster layer (i.e. buildings, trees, 2D vegetation, and surfaces) to ASCII format and then to CSV format. Then the text files for each layer were replaced with its relevant text in the ENVI met input files (the input files can be edited as a text file). To build the required parameters for trees, I used a Python script that reads the raster layer and generates a tree field for each tree in the ENVI met input file. This method for generating the input files facilitates the procedure of creating input files that would otherwise be a very time consuming task using the model design module of ENVI met. Using this procedure, I efficiently generated 10 poli cy scenarios. Weather data: T he ENVI met model simulates ambient temperature, wind speed and direction, humidity, turbulent fluxes, and several other microclimate variables (Bruse, 2013) at multiple heights. To initiate the model, several variables, inc luding soil moisture and temperature at different depths, must be set. I forced the model with hourly weather data obtained from the MesoWest website (University of Utah, 2016). I obtained hourly temperature, wind speed and direction, precipitation, and re lative humidity from the closest weather station in the MesoWest network for each site to provide the regional weather contexts of our simulation models. The model needs specific humidity at the elevation of 2500m as one of the initiation values. I used At mospheric Soundings data provided by the University of Wyoming (University of Wyoming, 2016). T o find an appropriate day for our microclimate simulation, I used the recorded values of light, relative humidity, and temperature collected by the data loggers. I used the light data ( Figure 47) to find a cloud free day, the relative humidity data ( Figure 48) to find a precipitation free day, and the temperature data ( Figure 46) to find the warmest day in the study period that also met the other two criteria. Based on the recorded data, I chose June 29th, 2015 which was relatively warm (T max = 35C), was cloud free, and had no precipitation. Figure 46 and Figure 47 and Figure 48 show the variation of temperature, light, and relative humidity, respectively, for an exa mple period

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139 (June 20th – July 5th) for one of the data loggers located in Belmar. The data collected by the data loggers are only used for choosing an appropriate day for simulation and then validating the model results, not for forcing the models. Figu re 46 Temperature variations collected by a data logger in Belmar (sample period: June 20th July 5th )

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140 Figure 47 Light variations collected by a data logger in Belmar (sample period: June 20th July 5th) Figure 48 Relative humidity variations collected by a data logger in Belmar (sample period: June 20th July 5th)

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141 Soil Data : I used Web Soil Survey (USDA, 2016) and Natural Resources Conservation Services data provided and maintained by the USDA to retrieve soil moisture and temperature information. Table 17 shows the initial values of soil temperature, soil moisture and meteorological data used in the model. Table 17 The initial values of the models Initial Values Belmar Boulder Soil data Temperature, (0 20cm depth) 292K 292k Temperature, (20 50cm depth) 294K 294k Temperature, (50 200cm depth) 298K 298k Relative humidity, (0 20cm depth) 17% 17% Rel ative humidity, (20 50cm depth) 19% 19% Relative humidity, (50 200cm depth) 25% 25% Meteorological Data Wind speed 10m above ground 2.2 m/s 2.6m/s Wind direction 300 North=0 270 North=0 Roughness length 0.01m 0.01m Specific humidity at model top 2500m 3.09 g/kg 3.09 g/kg Validation of simulated results: To evaluate the accuracy of simulations, I used the data collected by data loggers as the observed temperature to measure the error of simulated temperature. The simulated temperature is averag ed hourly from the air temperature outputs at 1.8 meter and the observed temperature is logged each 10 minutes (data loggers were located at the same elevation). I calculated the average

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142 hourly value of observed temperature for all locations and compared t hat with the simulated temperature for the exact location. To measure the error, I used RMSE (Root Mean Squared of Errors) offered by Willmott (1982). Equation 4 presents how to calculate RMSE where N is the number of cases, P is the value of modeled (predicted) temperature, and O is the value of observed temperature. I set the ENVI met simulations from 3am to 23pm (20 hours total). As a result, N equals 20 and i refers to each hour. Equation 4 Root Mean Square Error (Willmott, 1982) RMSE = [ ( ) ] . As RMSE informs the average difference (error) and does not report any information about the type of error, Willmott (1982) suggested measuring index of agreement ( d), systematic, and unsystematic RMSE. The index of agreement ( d) is a descriptive measure that reports relative and bounded measure ( Equation 5). In this sense, d reports the error occurred in the trend or the pattern of variations. Willmott also suggests measu ring systematic and unsystematic RMSE; systematic error reports whether a model is failing a variable that causes a general underestimation and overestimation. It is preferable that unsystematic error of a model approaches RMSE while the systematic error is small or approaches zero. Middel et al. (2014) use the same indices to measure the error of microclimate simulation by ENVI met. Equation 6 and Equation 7 present how to calculate systematic and unsystematic RMSE. Other studies have evaluated ENVI met simulations using these indices and concluded that the model simulates microclimate parameters with an acceptable error. For example, the research that Middel et al. (2014) have carried out simulates microclimate of residential neighborhoods in Phoenix. I can compare my simulation results with this study as a similar study. Equation 5 The equation for calculating d (index of agreement) d = 1 ( ) ( | | | | , 0 1

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143 Equation 6 Systematic Root Mean of Square Error = [ ( ) ] Equation 7 Unsys tematic Root Mean of Square Error = [ ( ) ] Equation 8 = + Urban microclimate simulations I ran ENVI met for all scenarios for a 22 hour period from 1am to 11pm for June 29th, 2015 using the forcing data introduced in the previous section ( Table 17). I visualized the 3D model output grids using Leonardo and exported hourly maps for each variable to a spreadsheet. I constructed a 250 x 250 twodimensional grid for each simulation area in ArcGIS using the Fishnet tool and joined the spreadsheets to the ArcGIS grids. I chose air temperature, mean radiant temperature, wind speed, and wind direction variables at 2meter above ground level. Policy Scenarios To assess the impact of policies on microclimate and compare the two study sites, I developed four policy scenarios in addition to the existing situation . The scenarios are critical to the methods. The scenarios address the differences in policies that generated the different built forms in Belmar versus the 29th Street Mall. The variables I used to build the scenarios include: ( 1) building height, ( 2) street directions, ( 3) tree density, and ( 4) a combination of all ( Figure 49) . One of the alternative to policy scenarios would be design scenarios. I did not run some different imaginary design scenarios because it does not inform policy choices. In order to focus on policy choices, I used the framework of policies and regulations as the leads to design the scenarios. I used my previous research experiences in relation to urban heat, the pilot study of this dissertation and the available literature on heat mitigation. As it is extensively di scussed and summarized in the literature review chapter, building height, street forms, and trees can play a significant role in shaping microclimate.

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144 Figure 49 Site layouts for the existing condition scenario Building scenar io: As I explained before, buildings in Belmar are taller, and this is consistent with the zoning regulation in Lakewood. To detect how variations of building height have affected microclimate, I simulated a switch in the building heights of the two sites and modified the ENVI met input files of each site accordingly. I increased building heights in Boulder’s site to match them with average heights in Belmar (45 ) and decreased building heights in Belmar’s site to match them with Boulder’s regulations (25 as the average of 15 35 ). Figure 50 shows the site layout of this scenario. The main question is how microclimate would change, if different design policies and approaches were in place for each site. comparison of policies at t he two sites shows that buildings are regulated differently. In the 29th Street Mall of Boulder, zoning at the time allowed 55’ building heights. Despite the opportunity of building taller buildings, for two reasons in the final plan buildings are as short as 15’ on the western side of the site and 30’ on the eastern side. First, the city of Boulder measured the height from the basement level. This complication was due to filling the land to mitigate flood plain. Second, the designer and developer of the si te chose to keep the western side of the street one story (15’) to preserve the view of mountains.

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145 Figure 50 Site layouts for the building scenario Street pattern scenario: this scenario focuses on the patterns of streets in both sites. In Boulder, the main street is NorthSouth and there is no East West corridor evident. In Belmar, the main corridor is East West while there are narrower North South streets. In general, the pattern in Belmar is a grid pattern while in 29th Street Mall of Boulder is mainly a linear pattern. I switched the main pattern of both sites to match the street directions and patterns with the other site. Figure 51 presents the changes I made on the street patterns. Fig ure 51 Site layouts for the street scenario

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146 Vegetation scenario: one of the visible differences between the two sites is the location and intensity of trees. Belmar has higher tree coverage compared to Boulder’s site, while 29th Street Mall has a few trees and most of the site is impervious surface. In the main street of 29th Street Mall, there are a few young trees, while Belmar has more mature trees, because the developer of the site bought mature and established trees to plant. The density of trees on the main street of the 29th Street Mall is 0.017 trees per linear foot (17 trees in 1000 feet) and in Belmar is 0.05 trees per linear foot (67 trees in 1300 feet). The difference in density of trees can impact microclimate in diffe rent ways. Trees provide more shade and therefore reduce mean radiant temperature in small spots. To measure these differences , I altered tree distribution in both sites. Figure 52 shows the site layouts for this scenario. I appli ed the tree density of Belmar in 29th Street Mall’s site (0.05 tree per linear feet) and reduced the tree density in Belmar to match that with Boulder site’s density (0.017 tree per feet). Figure 52 Site layouts for the vegetation scenario Combined scenarios: I created a scenario for each site that incorporates all the above variables (tree density, building height, and street pattern). In Boulder, I ran a simulation for a site with taller buildings, connected street corridor s for creating urban canyons, and higher vegetation intensity, whereas in Belmar I created a site plan with non grid street patterns, shorter buildings, and less tree density. Figure 53 shows the site layouts of this scenario.

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147 Figure 53 Site layouts for the vegetation scenario Component 2: Policy Evaluation The impact s of policy on shaping urban form elements are not direct and explicit; although it is very significant and central for the practice of planning and design. The first component of this research provides a critical scientific knowledge on how urban form affects urban microclimate. Having that knowledge in hand, now, the next research question explores how the policy choices were made in a w ay that generated such form elements. For example, why are building height regime s different in Belmar with Boulder’s 29th Street Mall ? To explore such policy choices, I need to layout the context in which planning were practiced. This needs an in depth qualitative analysis of procedures and decisions. The second component, juxtaposes the two case studies to draw the differences and similarities of their regulations, contexts, and decision making processes. The process of policy implementation that leads to microclimate disparities contains a complex nexus of variables shaping the physics of heat absorption and transfer. I used a case study research design for this component. Yin (2009, P:35) introduces three criteria for deciding whether a case study design is warranted (1) When “how” or “why” questions are raised, (2) where the “boundaries between phenomenon and context are not clearly evident,” and (3) where we explore a “contemporary phenomenon within a real life context.” In general, a case study research would be preferred when we explore a rich phenomenon that poses distinctive processes that reveal procedures that might be visible in other cases. Schramm (1971, c ited in Yin, 2009, P: 70) suggests that a case study is a better method for subjects that r equire illuminating “a decision or set of

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148 decisions: why they were taken, how they were implemented, and with what result.” Policy making processes leading to regulating built environments are a good example for such phenomenon for which using a case study research fits well. In my research, a case study research enables me to analyze complex relationships, approaches, and procedures through identifying variables and causes rooted in the planning practice. Three main reasons justify using a case study desi gn for this component. First, shaping a built environment through planning and policy making is a complex social phenomenon. The regulations and site plan in each case is the product of several key players. Each case has a unique socio economic and governa nce characteristics and contexts shaped by interactions of multiple key players, including planning practitioners, politicians, consultants, developers, investors, and public participants. This requires indepth analysis of processes. Secondly, finding com parable cases would be very difficult because the context of policy making, goals, and objectives could be fundamentally different. This provides limited opportunities to have control over the situation and processes. Thirdly, the way built environment sha pes microclimate is a very complex process and in different climatic conditions, we may need a separate set of policies. This makes every case a very unique combination of variables for this type of study. Although these relationships could be explained by scientific rules, there are numerous variables that are unique in the context and the region of the cases. For example, the climate of the Denver metro area creates a different simulation procedure compared to cities on the West or East Coast and conseque ntly, the policy implication of microclimate would be different. Answering my research questions needs a holistic approach that connects the policy implementation process to their scientific analysis of microclimate consequences. Therefore, I can benefit f rom using a case study design for the Policy Evaluation component. According to Yin (2009), for a case study research design, five components are essential for consecration: (1) the type of question should refer to a complex process through raising “why” a nd “how” questions; (2) propositions should address the context and situation of the study and could be exploratory; (3) unit of analysis should be limited to one or a few cases for an indepth study; (4) an appropriate logic that links propositions to the data through creating a “chain of evidence and rival explanations”; (5) the type of methods for interpreting the findings.

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149 Exploring policy making and implementation processes requires indepth understanding of dynamics between multiple individuals and i nstitutions, including city officials, developers, planning professionals, and the public. This goal meets all five main components of a case study design framed by Yin (2009). I raised “why” and “how” questions that refer to a complex procedure: the polit ical, economic, and social history of these two sites as a context that shapes the propositions that are strongly pertinent to the phenomenon. Theory: In a case study research , the propositions, questions, and the data that links these two can lead to a t heory development process. This theory is different with those grand theories in the field. This theory is just a guid e for me to design the research and collect the data. The theory explains relationships between the key players behaving in a complex cont ext. The theories lead me to collect relevant data and utilize appropriate analysis methods. Thus, to have a compass, theory development is fundamental before data collection and analysis. This theory will fill the gap in the theoretical discussion of the planning process. For example, my theory would explain under what circumstances a progressive site plan might be perceived plausible, whereas in a similar governance framework it does not. My theories will explain both organizational and societal character istics of policy making and the implementation process. In addition, theories in this sense define the level and format of generalization. Yin (2009, P: 117) uses the term “analytical generalization” versus the term “statistical generalization.” The findin gs might be generalizable on organizational or social dynamics of policy making; however, the context of each case would add myriad alternatives that require other theories to understand the real situation. Therefore, theories in this sense would be very s pecific. Yin (2009, P: 120) argues, if two or more cases with similar contexts support the same theory, “replication may be claimed.” Data collection for the case study research: This component uses three main data sources. (1) policy documents including z oning, design guidelines, and comprehensive plans. (2) Newspaper archives that covered and reflected the redevelopment procedures, interviews with related people, and conflicts around the projects. (3) interviewing the key players of each project including the developer, consultants, designers, city council members, city staff, and engaged citizens.

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150 Policy document: I collect ed the main policy documents reflecting development, renovation, and landscaping regulations . I review ed comprehensive and master pl a ns for PUDs, zoning ordinances, design guidelines, and other official regulations for each site. Most of these documents are available online and I received more detailed versions from the cities of Lakewood and Boulder. Newspaper articles: there are a few local newspapers that covered issues and stories around these two projects. I investigated related articles on websites of BizWest, Colorado Daily, and Boulder’s Daily Camera. 29th Street Mall in Boulder have received a more extensive coverage compared to Belmar. The reason is that the development process of 29th Street Mall was impeded due to significant conflicts between the developer team, city of Boulder, and city council. The conflicts delayed the project and attracted the attention of the public. The related articles were collected for content analysis that is explained in the analysis methods section. Interviewing key actors: One of the key principles to ensure the construct and internal validity is cross checking the findings in a chain of evidence or alternative explanations. Interviewing the key players in each project will enable me to (1) learn about the stories from perspective of each actor (developer vs city officials) and (2) compare these stories with newspaper articles that provides a fresh reflection of conflicts at its time. Putting together facts and claims from newspaper articles, interviews, and the built evidence on the ground provide parallel paths to check the role and importance of each variable. Interviews : I interviewed stakehold ers from each project, including city staff, planning and design review board members, city council members, developers, consultants, and local experts. I identified most of the interviewees from the news archives and then us ed a snowball method to find additional key individuals. I interviewed 11 people for 29th Street Mall in Boulder and 8 people for the Belmar project in Lakewood. The interviews were openended because the roles of interviewees were very different. Six interviewees were asked for a secon d interview to cross check facts and issues not covered in the first interviews. Interviews were transcribed and coded. Based on the simulation results described in the results chapter , this policy analysis focuses on regulatory factors that affect building heights, tree density, and morphology/alignment of streets. The interview instrument is attached in the appendix 1. To Prior to developing the interview

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151 question, I reviewed and coded the newspaper archives to create a timeline for the projects and to highlight the main events and conflicts. Data analysis for policy evaluation To understand in what regulatory contexts the key planning and design choices were made, I conducted a content analysis to highlight the differences of the policy document s . The c ontents of zoning, comprehensive plans, and design guidelines were scrutinized. I coded and tabulated all the contents including policy, newspaper archives, and transcribed interviews. I started coding with a wide range of variables and then narrowed them down to a short list of variables and themes. Figure 54 shows the content analysis process of the interviews. Table 4 also shows the codes and themes that emerged from content analysis of all contents.

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152 Table 18 Interview codes and themes Main category Variable Code Abbreviation Specificity of design guidelines Landscaping regulations SLR Vegetation regulations SVR Land value Economy, financing, ownership EFO Zoning type Mixed use development MUD Fle xibility/PUD PUD FBC vs Euclidean FBCE Building height limitation BHL Planning history Conflicts between stakeholders CNF Trust and history of relationships THR Authenticity of the project ATP Quality of parties Individuals QIN Quality & cohere ncy of City's guidance QCC Quality of design review board QDR Quality of developer QDR Entrepreneurial City ENC Planning vision Street pattern STP Vision for the site VSIT Vision for the use VUSE Producing consumer space PCS

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153 Figure 54 Content analysis of interviews Validating the accuracy of the information Interpreting the meaning of the themes Generating codes of themes Reading through the data Transcribing interviews

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154 IV. CHAPTER FOUR: RESULTS In this chapter, I present the results of two components of the research. The first component concerns simulation of the urban microclimate based on urban form configurations a t two urban redevelopment case study sites in the Denver metro region – Belmar in Lakewood and 29th Street Mall in Boulder. In this component, I will discuss how different urban morphologies and form elements shape urban microclimate outcomes such as air t emperature, MRT, wind speed, and wind directions. The results of the first component shed light on the way forms and microclimates are related. We learn how urban heat can be mitigated and what configurations are more effective in mitigating the urban heat island effect. The contribution of this part of my research enables planners and urban designers to quantify the magnitude of influence of form modifications on heat mitigation. Also, we learn how diverse microclimate variables are and how they vary in sp ace and time at each site. The variables were studied in this dissertation are ambient (air) temperature, mean radiant temperature (MRT), wind speed, and wind directions. For example, variations of MRT have different patterns compared to air temperature va riations in different hours of day and night. To understand how form configurations matter for each site, I built five scenarios that emulate policy differences of the two sites. Comparing the scenario results reveals how modifications of form elements aff ect microclimate. The comparison of policy scenario simulations highlights how policies affect those forms. The second component of the research utilizes the knowledge produced through the simulations of the first component. Knowing that parameters such as tree density and size, building height, and street pattern affect microclimate, I explored the procedure of planning, particularly the review processes, to scrutinize the decision making process. In this phase, I analyzed interviews I conducted with various people involved in the development process of the two sites. In this chapter, I present the results of content analysis in relation to policy documents and those interviews. The results of this component helped me to understand how the differences in form elements and morphology of two sites were systematically generated in the redevelopment process. At the end of this chapter, I present some variables that played an important role in the decisionmaking process. These variables exist in any redevelopmen t process and controlling them could help planners in achieving environmental goals. Component one: Microclimate Simulation

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155 To report the results of the first component, firstly, I report the main simulation results and their validation assessments. Then I introduce the policy scenario simulations their results. Simulation Results The outputs of ENVI met climate simulation software can be represented in a 3D environment. There are various variables (heat fluxes and air circulation regimes) such as air tem perature, mean radiant temperature (MRT), surface temperature, wind circulation etc. These variables are distributed in a 3D raster. In this dissertation, I transferred this data to a vector grid for presentation. F igure 55 and Figure 56 present the distribution of simulated air temperature and wind speed in both sites at 2 meters above ground at 3pm. The simulations of existing conditions in both sites provide interesting i nsights about the distribution of temperature. The RMSE between simulated temperatures and values recorded by all data logger locations range between 1.15oC to 2.35oC. The simulated temperature distribution shows an edge effect in both sites. The edge effe ct occurs because the model does not know how the urban environment is composed outside the model area. Although we used cyclic forcing for the simulation, the simulated values at the edge of the models are still not accurate. I did not use the edge cells for exploring simulation results. The range of errors are comparable with reported errors in other simulation studies. At the 29th Street Mall site in Boulder, the model overestimates air temperature in the early morning. Later, between 8am and 2pm, the e rror has different patterns depending on the location of data loggers. In two sites the model slightly underestimates the temperature; in others, it overestimates. In this morning period, however, simulated and observed temperature values are closer. The m ore considerable error is related to afternoon hours (3pm 10pm). The patterns of errors in Boulder and Belmar are very similar in most locations. In most of the data logger locations the simulated temperature is slightly (1 2oC) higher than observed temper ature on average.

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156 Figure 55 Distribution of Simulated Air Temperature at 2 meters above ground at 3pm on June 29th 2015 for Belmar (left) and 29th Street Mall (right) Figure 56 Distribution of Wind S peed (meter/second) at 2 meters above ground at 3pm on June 29th 2015 for Belmar (left) and 29th Street Mall (right)

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157 Figure 57 Measurement regions and mean radiant temperature in Belmar (existing condition) Figure 58 Measurement regions and mean radiant temperature in 29th Street Mall in Boulder (existing condition)

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158 Figure 59 Simulated versus observed air temperature in the data logger number 3 location of Belmar Figure 60 Simulated versus observed air temperature in the data logger number 4 location of Belmar

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159 Figure 61 Simulated versus observed air temperature in the data logger number 2 location of Boulder Figure 62 Simulated versus observed air temperature in the data logger number 3 location of Boulder The proportion of unsystematic error seems higher than similar studies such as Middel et al. (2014) and Emmanuel and Fernando (2007). Thi s could be because of the slightly lower accuracy

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160 of logged temperature in this study. Since the sensors were attached to walls, the temperature readings are potentially affected by the temperature variations of walls. Since we did not have the option of c hoosing perfect locations to collect data in a controlled environment, the distribution of errors is also different. The index of agreement ( d) in our study ranges between 0.96 0.99. Considering the different components of error in our study and comparing them with other studies that used ENVI met for microclimate simulations shows that we reached a similar accuracy. However, a more controlled environment for data loggers would improve our validations. That being said, the model is adequate for the purpos e of this study. Since the sites are not geographically very close (their distance is 23 miles), they already have different microclimates because of the regional regimes. The observed and simulated temperatures in Boulder are lower by about 1oC. This is e xpected specifically knowing that the context of these two sites are different. The City of Boulder is closer to mountains and has significantly higher coverage of urban trees in general; whereas Lakewood has a higher proportion of impervious surfaces and fewer urban trees. Therefore, these sites are located in different contexts that I am not including them in this study. For the purpose of this study, I am exploring how the site designs have affected the microclimate. Therefore, a direct comparison of these two sites is not in the scope of this study. Scenario results For each of the five scenario simulations (existing condition, tree density, building height, street pattern, and combined), I compared four ENVI met output variables: air temperature, mean radiant temperature (MRT), wind direction, and wind speed. My hypothesis at the beginning of the study was that the ambient temperature would be very different due to the site morphology. However, the results and outcomes of scenarios showed that air temperatures may not be adequate. Thus, I added MRT as another important microclimate measure. MRT is an important factor for outdoor thermal comfort. We found that in different variations of the built environment, air temperature does not change considerabl y, however MRT is directly related to shade and can vary significantly. In some studies, MRT is used as one of the factors affecting walkability (Emmanuel and Fernando, 2007) because that is the temperature that people feel on the site. For example, while the ambient temperature of a shaded space is not very different with an unshaded space, the mean radiant temperature would be dramatically different. This

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161 difference defines the level of comfort of the users. Comparing the maps shows that building height does not considerably impact air temperature. However, it significantly lowers MRT in the morning and afternoon hours. In addition, street patterns shape wind direction and speed. As a result of changes in air movement, ambient temperature is also affected. Figure 63 and Figure 64 compare simulated air temperatures of all scenarios for Belmar and the 29th Street Mall, respectively. The changes in scenarios are spatially variable. To measure these changes, I designated some comparison regions in each site and measured differences in the averages of air temperature, MRT, and wind speed. Figure 57 and Figure 58 show the location of the comparison regions in each site. The reasoning behind choosing the location and size of the comparison regions is that these are places where we detect potential differences such as urban canyons and shaded sidewalks . Figure 65shows a summary of microclimate changes across all scenarios. Appendix B presents the variations of ambient temperature, wind speed, and MRT for all regions of both sites. Figure 63 Simulated air temperature of scenarios of Belmar in Lakewood

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162 Figure 64 Simulated air temperature of scenarios in 29th Street Mall in Boulder

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163 Belmar (Lakewood, CO) 29 th Street Mall (Boulder, CO) Air Temperature Wi nd Speed Mean Radiant Temperature Figure 65 Comparison of microclimate variables across all scenarios where H values are hours of the day of simulation 29 30 31 32 33 34H12 H13 H14 H15 H16 H17 H18 BuildingHeight CombinedScenario ExistingScenario StreetDirectionScenario VegetationScenario 28 29 30 31 32Average of T6 Average of T5 Average of T4 Average of T7 Average of T8 Average of T9 Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Height Scenario Combined Existing Scenario StreetDirection Vegetation -0.1 0.2 0.5 0.8 1.1 H 0 H 1 H 2 H 3 H 4 H 5 H 6 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 BuildingHeight CombinedScenario ExistingScenario StreetDirectionScenario VegetationScenario 0.6 0.65 0.7 0.75 0.8 0.85 0.9 Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Average of Height Scenario Combined Existing Scenario StreetDirection Vegetation 10 30 50 70 H4 H5 H6 H7 H8 H9 H10 H11 H12 H13 H14 H15 H16 H17 H18 H19 H20 BuildingHeight ExistingScenario 0.00 20.00 40.00 60.00 80.00 Average of T6 Average of T5 Average of T4 Average of T7 Average of T8 Average of T9 Average of T10 Average of T11 Average of T12 Average of T13 Average of T14 Average of T15 Average of T16 Average of T17 Average of T18 Average of T19 Average of T20 Height Scenario Existing Scenario

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164 The policy scenarios show changes in all three variables. However, the variations are local and depend on the relationships between built environment and microclimate components. To spot the differences among the scenarios, I visualized the results across the space and time dimensions. Through probing these variations, I highlight three main findings: (a) Building height : air temperature changes related to the building height scenarios are minor at both sites. Building height might change the overall microclimate of the entire site, however at the scale of the comparison regions I am not able to detect any change. At 29th Street Mall, there is a slight change in wind speed (0.05 meters per second [m/s]) between the existing condition and building height scenario. However, it does not seem that this difference drives a sign ificant change in air temperature. I also compared MRT of the building height scenario with the existing condition and found that taller buildings provide more shade in the public space, thus reducing MRT, which improves outdoor thermal comfort on hot summ er days. Thorsson et al. (2007) also show how the influence of building morphologies on the sky view factor is one of the main variables controlling MRT. Taller buildings may not have a direct impact on air temperature, but their shade can create much more comfortable spaces for users of public spaces. Figure 66 presents the difference of MRT between the building height scenario and the existing condition in region 7 (as marked in Figure 57 ) in Belmar. As it is expected, the shorter buildings used in the building height scenario for Belmar increase MRT in the morning (7 10am) and afternoon hours (2 6pm). My own hypothesis was that ambient temperature would be significantly d ifferent but as the results show, the difference of ambient temperature in different scenarios are not remarkable. That is why the mean radiant temperature become the central variable of the outcomes. This is also noticed by other similar studies such as M iddel et al. (2014).

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165 Figure 66 Comparison of Mean Radiant Temperature (MRT) for the building height scenario (shorter building height) and existing condition in region 7 of Belmar (b) Tree density scenario: Trees affect microcli mate through various mechanisms. One of their most important effects is providing more shade. From this perspective, they are very similar to the shade provided by buildings. Simulated air temperatures by ENVI met do not show a significant difference between the tree density scenarios and existing conditions. However, as Figure 57 and Figure 58 show, MRT drops around trees as the shade impact and reduced radiation, creating better thermal comfort on the sidewalks. (c) Street pattern scenario: changing the pattern of streets affects the air movement regime and thus temperature. This raises a more important issue. When the air moves along streets, what is the temperature of th at air? Has it already been warmed by the urban environment, or is it cool air? This depends on the site design, site location, and landscaping strategies. In both Belmar and 29th Street Mall, the dominant wind direction is from the west. For example, in B elmar, changing the street pattern from grids to a more linear pattern increased wind speed in region 9. As Figure 67 shows, a 0.1 m/s increase in wind speed reduces air temperature by about 0.5oC. Furthermore, at 29th Street Mall extensive parking lots are located on the west side of the site. By facilitating air movement through the creation of urban canyons at this site, air is moved that is already warmed by the asphalt parking lots. Figure 64 clearly shows that creating a grid pattern in the Boulder site exacerbates warm air temperatures in regions 4 and 6. Therefore, we see that changing street patterns to create urban canyons or enclosed spaces can either mitigate or exacerbate heat 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Mean Radiant Temperature C BuildingHeight ExistingScenario

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166 depending on the site morphology. In fact, for any site design, the important variable is knowing the direction and intensity of air movement. Some features in a site may generate heat (i.e. parking lots) and some other features may mitigate heat (i.e. trees and grass). Knowing what the dominant wind is in the warm season, we would know whether wind carries the warm or cool air. Figure 67 Comparison of wind speed and air temperature for the street pattern scenario (linear layout) and existing condition (grid layout) in region 9 of Belmar 1.02 1.07 1.12 1.17 1.22 29 30 31 32 33 34 35H12 H13 H14 H15 H16 H17 H18 H19 H20Wind Speed m/s Air Temperature CHour Temperature Existing Condition Temperature Street Pattern Scenario Wind Speed Existing Condition Wind Speed Street Pattern Scenario

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167 Table 19 Summary of simulation results ( = effective in heat mitigation) Belmar 29 th Street Mall Notes Buildings Tall buildings Short buildings Tal ler buildings reduced MRT significantly and air temperature slightly Tree Density High tree density Low tree density Trees reduce air temperature and MRT significantly Street Patterns Grid streets Linear Streets are important for air movement. They ca n channelize air, speed up its movement, and carry cool or warm air. If the air passes over a heat generating space such as a parking lot, a street could move warm air to other spaces. A vegetated surface can cool down air and street patterns could be help ful for carrying the cool air to public spaces. Boulder blocked the warm wind from penetrating to the site generated by vast parking lots on the west side of the site. Replacing the parking lot with vegetated area would generate cool air and then the street pattern could change to benefit from such air movement. Overall, both sites could have a more efficient air movement.

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168 Component two: Policy Analysis In this section, I report the results of the second component of this dissertation. As it was explain ed, the first component informed how different morphologies and form modifications shape urban microclimates in 29th Street Mall and Belmar. The fundamental question in the second component is how planning policies generated such differences in forms and m orphologies. Following this question, I pursued more detailed questions in relation to policies and decisionmaking procedures. How did different approaches to zoning impact microclimate related form elements? I specifically explored the differences between form based codes versus Euclidean zoning. The other main policy variation I looked at is PUDs and the flexibility that they bring. I analyzed the contents of these policies to find relevant differences. In the next step, the other question I raised is how procedural differences can affect the decision making processes in such development projects. For example, why are buildings of Belmar taller than buildings of 29th Street Mall? Why does Belmar have more trees and how did they end up with buying mature trees instead of planting young trees like those installed at 29th Street Mall? In this section, I report the results of policy content analysis and coding of interviews. Before that, it is helpful to explain the development process of both sites. The s tory of two sites Knowing that Belmar is performing better in heat mitigation and creating more comfortable temperature, we explore differences in planning and design policies and implementation procedures. To explain why this component of the research is a case study design, we articulate similarities and differences at both sites. Location and regional climate: Both sites are located in the Denver metropolitan area. Boulder is in the northwest of Denver and Lakewood is in the west of Denver. The aerial distance between two sites is 23 miles. Although the general climate regime of the sites is similar, their locations relative to mountains and farm land in the Front Range creates different weather patterns. Belmar’s altitude is 5500ft whereas 29th Street Mall’s altitude is 5285ft. In addition, the general urban form of both cities has created different microclimates. Background: Both sites have very similar backgrounds. They were both indoor shopping malls developed in the 1960s surrounded by vast parking lots. In the mid 1990s they declined and

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169 had many vacant stores. In early 2000s they were redeveloped. The old shopping mall in Lakewood was Villa Italia and was demolished in 2002 to develop Belmar as a new mixed use urban center. The new project was ope ned in 2004. Like Belmar, 29th Street Mall was developed in the place of an old declining indoor mall, Crossroads Mall. The Mall was demolished in 2004 and 29th Street Mall was opened in 2006. Economic context: despite the similarities in their background s, these sites are in two municipalities that have very different contexts. The redevelopment projects happened in the early 2000s and went through 2007 when the recession started. In the Denver metropolitan area, Boulder has been always a stable economy and a more attractive place for real estate investors. Currently Boulder’s population is 108k, another 66k people commute to Boulder from Denver and other suburban municipalities every day. Housing prices have considerably increased in Boulder in the past d ecade ( Figure 68 ). Generally, Lakewood is a lower income community with an average $86k household income compared to Boulder with $96k. Median housing value in Boulder is $650k whereas in Lakewood it is $350k ( Cens us Bureau, 2017). Although these data are for the past decade, however, it shows the difference of the contexts. This shows that Boulder in general has been experiencing significantly high pressure in its real estate market. Thus, we see that redevelopment of these two sites occurred in two different economic contexts. Figure 68 Average housing value in Boulder and Lakewood (Zillow website, 2017)

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170 Planning contexts: as presented in the previous section, Boulder has been a popular destination for real estate investors even during recession years. Boulder has adopted a series of policies that limit the real estate market. For example, in addition to limiting sprawl through its open space, Boulder has a city wide building height limita tion (55’). Despite these limitations, Boulder has developed a cluster of high tech startups and businesses. While Boulder has strong policies to slow down growth, Lakewood has been a progrowth local government. Furthermore, Boulder is well known for its highly engaged citizens. Most projects in Boulder receive remarkable turnout at public hearings. According to our observations and interviews, some active citizen groups in Boulder strongly resist change and growth in their neighborhoods. Lakewood has a di fferent political environment. Citizens are less engaged and development projects such as Belmar could attract more investment as a catalyst project. A city with a weak economy can benefit from a flagship project to stimulate the market. Planning and desig n policies: Belmar has been zoned as a PUD (Planned Unit Development). According to the zoning ordinance of Lakewood, “the Planned [Unit] Development district is intended to permit the planning and development of substantial parcels of land which are suitable in location and character for the uses proposed and are suitable to be developed as a unified and integrated project in accordance with detailed development plans” (City of Lakewood, 2014, P:64). In addition to PUD, Belmar is zoned as M G U (Mixed Gene ral Urban) which uses a form based zoning approach. As a requirement for PUD, development of this site requires a comprehensive site plan and a design guideline. The general regulations on this site provide some flexibility of design while ensuring that th e general urban form is high density mixed use that fits an urban core morphology. 29th Street Mall in Boulder is zoned as BR 1, which is Business Regional 1. Boulder uses a conventional zoning approach. This zone is supposed to provide business centers f or the central region of Boulder and allows a wide range of retail and commercial uses, including the largest regional scale businesses. This zone also requires a “concept plan and site review.” The zoning regulates buildings as envelopes with some specifi c restrictions. For example, the maximum building height is 35 feet and maximum number of stories is 3; and maximum FAR is 4.0. Case study research design : as we explained, the cases have some similarities and differences that make a good case study design . Both sites are located in one region with similar

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171 climatic properties that has hot and arid summers. This makes them good choices for a microclimate comparison. Both cases have similar regional economic context as they are located in one metropolitan are a and are subject to similar state level policies. However, differences of local economy and planning polices and contexts enable us to control regional variables and investigate local variables of both microclimate and planning procedures. Furthermore, t he cases have different zoning approaches that create an interesting case for a comparison of new (FBC) and old (Euclidean) zoning approaches. Belmar uses PUD and 29th St Mall does not. We are able to investigate whether the flexibility and requirements of PUD have played a role in affecting urban microclimate. In addition to different policy approaches, the context in which planning is being practiced provides a good range of variation. In Belmar, the community and the local government are progrowth, wher eas in Boulder the city is very conservative in terms of growth and there is a significant public sensitivity around any redevelopment project. In fact, the planning review process is more intense and slower in Boulder. In such an environment, conflict of interests among all involved parties create considerable tensions in the procedure of planning. Knowing that Belmar is performing better in heat mitigation we investigate how policy variables shape these differences. As Yin (2013, P:35) argues, in a condit ion where “how” or “why” questions are raised and the research investigates a “contemporary phenomena within a real life context” a case study design is preferred. Exploring rich phenomenon posed as distinctive processes can reveal procedures that might be visible in other cases as well. Land use and building form controls: We reviewed the codes and regulations of both sites and found that zoning and design guidelines are the main tools for regulating form and use. However, there are significant differenc es between the two sites that influence their microclimates. 29th Street Mall, Boulder: The main policy documents for 29th Street Mall include (a) the general zoning regulations, (b) the general design guideline of the Boulder Valley Regional Center, and ( c) a design guideline provided for the project and adopted in 2005. a. Zoning: As we discussed before, 29th Street Mall is zoned as BR 1, which is a conventional zoning method to regulate building envelope and use. This zone requires a

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172 concept plan for the re view process. In this zone, the maximum building height is 35 feet and maximum number of stories is 3; and maximum FAR is 4.0. b. Boulder Valley Regional Center Design Guideline: this design guideline is for an area plan that is part of the Boulder Valley Comprehensive Plan. This design guideline was adopted in 1995 (about 10 years before redevelopment of the site). This document is mostly an advisory guideline and most content lacks specific regulations. For example, in a section dedicated to “Site Layout”, the code encourages locating buildings close to the street; however, this does not go beyond general advice: “Locate buildings close to the street, with parking behind and/or beside the buildings. Streets lined by buildings rather than parking lots are mor e interesting to move along, especially for pedestrians. If the property spans an entire block (fronts on two parallel streets), try to locate a building along each street.” In other parts, the guideline also uses flexible language. In the section of “Automobile Parking” the language is even softer: “Try to minimize parking needs” or “Try to provide structured, rather than surface, parking”. Clearly, the guideline offers some general directions for future site designs without providing any regulatory tool o r specific objectives. Assessment of the built elements of 29th Street Mall shows that most generic suggestions of the guideline were adopted; however, some specific details pertaining to the landscaping and trees of the built environment do not match the proposed principles. For instance, in Section 4.1.Q, a row of street trees is prescribed, however that was not implemented in the final site plan of 2005 ( Figure 69). “Section 4.1.Q Street trees are required in t he setback of certain streets A row of street trees is required in the landscape setback around the interior of the Crossroads Mall “block” and along the west side of 28th Street, to continue the established tree pattern. Linden trees should be planted 30 feet on center, at a 15 foot stagger from the row of Ash trees in the landscape strip. Littleleaf Lindens and Redmond Lindens are preferred.” Figure 69 Boulder valley design guideline

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173 c. 29th Street Mall Design Guideline: In theory , this document is supposed to regulate the specifics of site design and buildings for both the redevelopment and future developments. However, in this case the document provides a site plan rather than regulating for future buildings or changes to the sit e ( Figure 70). As Punter (2002) argues, design guidelines need to be visionary and provide detailed standards for landscaping that could be applicable for future changes. We do not see such details in the design gu ideline of 29th Street Mall. What we see in the design guideline of 29th Street Mall instead is a site plan of what was implemented, while lacking standards for the future. In other words, it is more descriptive rather than prescriptive. Figure 70 Design guideline of 29th Street Mall in Boulder Belmar: the main regulatory tools in Belmar include (a) zoning (a form based code and PUD as the overlay zone), (b) a master plan (required by PUD), and (c) a design guideline. a. Zoning: Bel mar is zoned as Mixed Use – Core Urban (M C U) with an overlay zone of Planned Unit Development (PUD). The MixedUse Core Urban zone reflects high density, with retail and building frontage for streets. This code permits various uses including residential, community public uses, offices, retail, etc. The building height minimum is 30 feet (2 floors) and the maximum is 120 feet. The massing and building placement is relatively flexible. The code follows the general principles of form based code for the

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174 urban context and highdensity areas. The Belmar site is also zoned as a PUD that requires a master plan and a design guideline. This allows the city to use a specific design review process while it provides flexibility for design; As Elliot (2008) points out, PUDs generate an onerous and complicated review process and are not an easy path for local governments. b. Masterplan: This document, prepared in 2002, provides the general layout of urban blocks, street profiles, and infrastructure. c. Design guideline : The c ity of Lakewood adopted the design guideline as a part of its masterplan in 2002. This document is regulatory (not advisory), visionary, and is framed to guide future changes. The site is divided into sub areas and each sub area has its own regulations and standards. Also, each street has a separate set of regulations. The design guideline lays out the standards and regulations for the site plan, architecture, landscape, and signs. Figure 71 shows some examples from the document on street ratios and landscaping of parking lots. Figure 71 Design guideline of Belmar Comparing the codes, it is clear that Belmar had a much more flexible foundation through PUD. The zoning regulations also re gulate in favor of high densities and taller buildings. Maximum building height in Boulder is 35’ whereas in Belmar minimum building height is 30’. FBC in Belmar has created a better and more active building frontage as well.

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175 Land economy: One of the them es that emerged from the content analyses and seemed to have significant influences on the process of plan making, review, and implementation is issues around land economy. We observed two main variables in relation to land economy: (a) financing and (b) l and ownership. The data shows that this variable played a remarkable role in the plan making and implementation process. We discuss the financing and ownership situation of each project. a. Financing the project: The Belmar project was financed by TIF (Tax In crement Financing) and the Southern Ute Indian Tribe. The tribe invests in a variety of activities including real estate and housing development. The manager of this project from the developer team of Belmar (Continuum) initiated a relationship with the Ute tribe. One of the interviewees who was an important person in this project stated: “An interesting thing about Belmar is that the developer went to the Ute tribe and asked their help for funding the project. They are fairly wealthy in terms of natural re sources and they wanted to diversify their investments. This was very helpful because the Ute tribe trusted the developer and provided funding without intervening in the design process.” The other important point in the Belmar project was the partnership o f the City, the Developer, and the Funder (Southern Ute Tribe). The City offered a TIF (Tax Increment Financing), of $100 million to pay for public infrastructure. In Belmar, there was not much conflict between the partners. Several interviewees mentioned that the city manager and the mayor of Lakewood had a great leadership. In the 29th Street Mall case, the situation was significantly different. The city and the developer did not agree on the amount of TIF. The city agreed on $58 million but the develope r, Macerich, wanted $80 million. Resolving this conflict took about two years. One of the interviewees who was a city staff said: “To determine whether to do a public or private partnership, it was a joint decision. I think that’s important. That was not t he decision of the city alone. It was not like Macerich comes and says hey will you fund the project and we said no. We had meeting after meeting and after meeting for months

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176 and months and months. The city does not do many TIF projects. We do it very rare ly. I sat in those meetings; Macerich also determined it was not their best interest to get the TIF.” Another interviewee who was involved in the negotiations as a council member said: “They wanted this money to build parking lots and we did not want to pay for the parking. It was not worth it. I don’t think we would have gotten a different plan from them even if we had agreed to the $80 m TIF”. One of the interviewees who was a city staff did not see this as a conflict: “There was not much conflict; both sides ran the numbers and reviewed the options and the decision was made that it was better for them to keep it a private project and the City decided to use a regular planning review process.” Whether we name it conflict or negotiations, it seems that be tween 2002 and 2004 the city and the developer could not agree on public funding and the developer chose to keep the project private. One of the highlevel people from the developer team said ( Storum, 2003): “Macerich will not pay for the redevelopment wit h TIF or subsidy of any type. It’s a private project. As long as we were willing to fund this 100 percent out of private sources then the city wouldn’t get into the business of telling us what to do.” b. Ownership: the ownership of the land in each project w as a complex problem. Since both sites used to be indoor shopping malls, there were numerus business owners that needed to agree for such redevelopment. In Belmar, the city used condemnation to deal with some retailers who held the property. Then the deve loper bought the land. The condemnation process took about two years but eventually helped the developer to demolish the whole site and implement a new site plan. In 29th Street, the ownership was much more complex. Parts of the site were owned by family trusts. The family trusts held the land and did not agree with the redevelopment plans. This added more complications to the financial tensions. Although some ideas were discussed in the city

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177 council to buy the whole land by the city, the council members c ould not agree on this option. Also, the city did not want to go through the condemnation process. One of the council members said: “It would make the project much more complex; it would be a very expensive, long, and exhausting process. We would have lost our tax revenue.” Most of the site was owned by Macerich; the other parcels were bought by Macerich eventually. The fact that the site was owned by an entity who is a large scale regional shopping mall developer made the project very complex. Macerich did not want to give up the land and the city knew that Macerich did not have a vision to develop a mixeduse urban center. Multiple interviewees including city staff, council members, and design consulting firm representatives explicitly verified this. c. Loca l economy: Each city has its own local economy. This affects any redevelopment project. Boulder has been a popular destination for businesses with a steady and reliable real estate market. On the other hand, Lakewood has a weaker economy with more low inco me residents. The local economy affected these two projects in at least two ways. First, the mall in Boulder had still been working despite the general decline. Some stores wanted to continue the business. Foley’s (owned by Macy’s) did not agree to close the store. Macerich did not want to force them to close for demolition. One of the interviewees said: “Macerich owned 25 regional malls in the country and had a deep relationship with Macy’s (they owned Foley’s). Macerich did not want to force them to clos e the store for redevelopment because it would have hurt their relationship.” Eventually, they kept the building and continued the business even through the construction. This building is still on the site and is not wellintegrated with the site. The situation in Lakewood was different. The city of Lakewood needed change; thus, they were pro growth and willing to raise the property value using the site as a catalyst project. The mall also was completely vacant which made purchasing the property much easie r.

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178 Planning contexts: The local politics and social dynamics of each city create an environment that affects the process of plan making and implementation. Considering that Boulder is an attractive destination, active citizenship accompanied by a signifi cant housing shortage has created an intense real estate market in a city where density is remarkably limited. Whereas, in Lakewood, citizens advocate for growth to attract more investment to their fairly low income suburb of Denver. The participation of citizens in the process of planning is known and discussed in community planning and urban renewal projects. As discussed by Campbell (2006) and Forester (1999), public engagement can improve the planning process. However, what we observed in our collected data is that active citizenship and sensitive citizens created complex local politics. The City of Boulder is famous for its sensitive citizens about new projects or basically any change. They actively engage in the process of redevelopment, any changes t o the built environment, and the modification of relevant policies. Several of our interviewees referred to this phenomenon as NIMBYism (Not in My Back Yard). One of the interviewees said: “Boulder is a very liberal city. You’d think that in a liberal city you would have better urbanism. The anti growth NIMBYs have made any highdensity project in this town almost impossible. It is so frustrating. This type of activism is against environmental values and this has become normalized in Boulder.” This slows down any process of redevelopment and engages staff time; thus the staff does not have enough capacity to adequately address and focus on the meaningful and qualitative aspects of the projects like what planning staff did in Belmar. Both pro growth and anti growth groups use public hearings, community forums, and local media to debate and negotiate options. This complicates the planning review process, ultimately making any project very controversial. Not only are the citizens active but also the city provide s the opportunity for discussion and opposition. One of the board members said: “The number of opportunities for comment is second to none here. You can go far and wide before you find another American city that opens its process the way Boulder does to the public.”

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179 Several interviewees verified that the social context in Boulder is very intense and citizens are very demanding and sensitive to any change in the city. Also, multiple interviewees believed that the city could be more aggressive in pursuing progressive goals even if anti growth groups are not happy. This conflicted context loads more work on to the city’s staff. As one of the interviewees, who is also a Boulder Planning Board member, comparing Boulder and Lakewood said: “Lakewood doesn’t hav e 50,000 concerned citizens beating down the door every time a project is proposed. A ’signature project’ [in Lakewood] gets all the attention, because 30 other projects flew under the radar. 29th St Mall [in Boulder] is just one of 30 projects [in Boulder] that are all getting scrutiny because nothing in Boulder is happening without scrutiny. So the department just doesn’t have enough time and staff to budget to this project because everything is so blessedly important. We live in a world where every pro ject is the End Of Boulder.” Planning vision: For an important project, such as Belmar or 29th Street Mall, all parties need to have a clear and progressive vision in order to create a walkable space that is sustainable with respect to environmental val ues. Both projects are important for the spatial structure and economy of the cities. Belmar is the new downtown Lakewood now and 29th Street Mall in Boulder could be another important center in the city connecting the east and west. Such projects require profound visioning to be done well. The vision of each project was shaped in the planning, social, and political contexts that we described; therefore, those limitations have affected the ability of cities in achieving their goals. However, we observed sig nificant differences in the process of envisioning for these two projects. 29th Street Mall in Boulder was owned by Macerich, a shopping mall owner/developer. The vision of the developer was not creating a mixeduse urban center with public spaces for act ive living or social interactions. The developer aimed to regenerate the mall as a consumer space with a different style. One of the interviewee said:

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180 “They demolished the old indoor mall and built an outdoor mall. Now they don’t need to pay for the air conditioning.” As explicitly stated in the news archives, the developer wanted to create a “lifestyle shopping mall.” They insisted on having a street with through traffic and pull in parking spaces. One of the city staff stated: “It was Westcor’s decision t o eventually want to have pull in parking; Westcor wanted some opportunity for people who wanted to drive through the site to be able to look around to find an opportunity to potentially find the parking space and therefore get more penetration.” We asked one of the City’s staff whether the City wanted an urban center project and Macerich wanted a mall. The interviewee answered: “When we finally came up with top ten goals for the site we were much more in line with Westcor. I never felt we are off in terms of the goals.” This is indicative of Boulder’s lack of vision for a true mixeduse urban purpose for this site. On the other hand, the city of Lakewood paid considerable attention to the Belmar project. The city hired a well known developer who had the experience of designing mixed use urban centers. The vision for Belmar was creating a mixed use center for everyone for families, for shoppers, and visitors. One of the city staff stated: “More than a year of collaboration between Continuum and the communit y resulted in a very different vision for the future of the Villa Italia site. A vision that accommodated the automobile but put the pedestrians first. It included a true diversity of uses. It organized the day and night time activity around the public rea lm of parks, plazas, and streets, which were pedestrian amenities. It emphasizes high quality of buildings with design integrity. We wanted to create an authentic place.” The design consultants were important pieces in each project and what we see as the b uilt environment today. The consultant in Belmar paid attention to the details of landscaping and vegetation. They suggested buying and planting mature trees in the site. They paid attention to the ratio of building height/streetwidth. The head of the des ign team for Belmar states: “We wanted to design narrower streets with 4 5 story buildings. I had a long debate with . [the head of developer] that Alaska street should be

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181 narrower. He insisted on a wider street. As soon as we built it, he did not like it but it was too late.” This meticulous attention to building height was also present in Boulder but in a different way. Boulder has the advantage of mountain views. Citizens, council members, and even city staff are sensitive to preserving the view. One of the city staff stated: “On building height, it was important to preserve the mountain view to take advantage of it.” The design consultant in Boulder also verified this intention and believed mountain views were important and that is why they kept the wes t side of the main street one story while the east side of the street is two story. Analyzing the data shows that the city and council in Boulder have not been able to have a progressive vision for this project compared to the city of Lakewood. The interesting point is that Civitas, a design firm which was the consultant in the Belmar Project, was hired by the Boulder Urban Renewal Authority to work on 29th Street Mall at the beginning. Civitas proposed a mixeduse urban center site plan that was discussed in the negotiations between 20022004. Figure 72 shows the “framework” site plan proposed by Civitas that shares some main design elements with Belmar. The contract of Civitas and Boulder Urban Renewal Authority f inished and Macerich, the developer of the project, hired a different consulting firm so this site plan was never adopted. Comparing the current 29th Street mall with Civitas’s design shows that the proposed site plan was much more progressive by featuring mixed use and pedestrian oriented elements. This raises a fundamental question: How could the city of Boulder have pushed this proposal more aggressively and forced the developer to adopt this approach?

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182 Figure 72 The site plan t hat Civitas proposed in 2002

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183 V. CHAPTER FIVE: CONCLUSION As explained before, this dissertation aims to bridge the gap between the science of microclimate to planning and design policies (Figure 1). I used microclimate as a complex subcomponent of urban e cosystem s . The question is how can we scientifically quantify the type of built environmental elements that can change urban microclimate? And then, w hat is the magnitude of change corresponding to each form variable? Illuminating this relationship will he lp urban designers and planners to understand how a regime of policies and procedures can impact urban ecosystems, in this case microclimate. The hybrid design of this dissertation made this analysis possible. First, I ran some simulations to understand how urban form elements shape microclimate variables; then I explored policy contents and policy implementation procedures to understand how making different choices in the planning process affect s urban form elements and consequently microclimate. Fi gure 73 Dissertation conceptual model and components Reviewing the microclimate simulation results shows that there is a significant temperature difference in each site caused by urban morphological features. I chose two sites tha t have similar contexts and histories of redevelopment. Nevertheless, each site’s redevelopment used unique urban planning and design policies. Belmar has a more flexible policy framework using a PUD zone and form based zoning as its foundation. 29th Street Mall in Boulder uses a conventional Euclidean zoning framework that limits building height. Differences in procedural planning practices at both sites have created disparate morphologies. The policy scenarios show that Planning and Design Policies Urban Form Elements Urban Microclimate First Component Second Component

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184 different choices in planning and design have the potential to produce considerable differences in urban microclimate. Building height policy at the Boulder site has created relatively short buildings and wide street canyons. These design and policy choices in Boulder have caused higher me an radiant temperature and consequently less thermal comfort in public spaces. The tree scenarios show that choices of higher tree density and larger trees in Belmar have contributed to heat mitigation, whereas at 29th Street Mall there is not enough tree canopy to create shade on sidewalks. Low tree density in Boulder was mostly the choice of the consultant and developer of the site, and the city does not have any mechanism to regulate it directly. Over time, as the trees of 29th Street Mall mature, they s hould do a better job of mitigating heat. The analysis also shows that changing the street patterns affects the microclimate of both sites. The grid street pattern in Belmar provides efficient air movement into the site. However, the scenarios indicate that while changing the pattern to a more linear design reduces temperature in some locations, it may increase it in some others. Therefore, optimizing the street pattern for heat mitigation should be targeted with important public spaces in each site in mind. An important issue in the design of streets is the location of impervious, permeable, and vegetated surfaces. These surfaces can generate micro islands of hot or cold air when they are extensive. The location of these surfaces is important relative to th e general wind direction. At 29th Street Mall, locating parking lots on the west side of the site generates hot air; therefore at least the existing north south linear street pattern prevents moving the hot air through the public spaces to some extent. Co nsidering all scenarios for both sites, it seems that Belmar’s morphology is more effective in mitigating heat. Applying the rules and morphology of Belmar to 29th St Mall of Boulder also shows that both mean radiant and air temperatures drop significantly . On the other hand, applying the rules and morphology of the Boulder site to Belmar exacerbated both air and mean radiant temperatures. It is clear that with respect to the goal of mitigating urban heat, Belmar’s morphology is performing considerably bett er. The analyses show that some form elements such as building height, trees and vegetation, and street patterns affect the microclimate variables significantly. The policy scenarios were a meaningful method to measure how the variation of policy and form could mitigate air and mean radiant temperature. Measuring the impact of a combination of form elements such as trees and

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185 street orientation is complex but achievable. The presented findings in relation to urban microclimate variables can be summarized by concluding that through form regulation we can improve the microclimate of public spaces. The form elements are a direct outcome of policy and development management procedures. The findings show that the choices made in the development management affect ed the microclimate of both sites. The built form of Belmar is more effective in heat mitigation and creating a more comfortable temperature. Based on the results of both my microclimate simulations and the policy analysis , I identified five main themes in the development management of both sites that control microclimate outcomes and show why Belmar ultimately was a better project. These themes, which are also relevant for other environmental objectives, are: (1) urban vision, (2 ) land use and building form controls, ( 3 ) design guidelines, ( 4) public financing, and ( 5 ) condemnation/ownership factors . These five policy themes I have identified explain how a combination of context and choice variations affect the quality of built environments. Urban vision: Within this framework, we can ask : did Lakewood, CO and Boulder, CO create a strong urban vision for these projects? It is very clear that the presence of such a vision in Lakewood resulted in a more walkable, mixed use, and environmentally friendly design. This design improved the microclimate variables mostly through a higher tree density and taller buildings. In Belmar’s case, the interviewees explained how the city made a partnership with the developer based on a more entrepreneurial approach from the e nvironmental perspective. The developer also had extensive experience in developing such sites before starting the project. In 29th Street Mall of Boulder I did not find any evidence that the developer or city had a strong environmentally progressive visi on for the project. The project is not mixeduse; the main street is very wide; buildings are even shorter than what the code would allow; and tree density is particularly low. The developer was an owner and developer of indoor shopping malls and clearly did not pursue a mixeduse high density urban center. The city of Boulder needed to be more intentional in vision making for the project through rezoning the site and partnership with the developer. As Godschalk ( 2004) shows, resolving conflicts in urban developm ent projects needs strong visioning that helps all stakeholders have a better understanding of the main goals and the conflicts around them.

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186 Land use and building form controls : O ne of the most significant differences between the sites was the specificity of codes in relation to form control . Belmar used a rezoning procedure envisioning a mixed use and high density site . Adding the PUD overlay provided control over the site with flexibility for the developer. Furthermore, Belmar uses a form based zoning tha t allows higher control on fine scale details of building forms, street characteristics, and landscaping qualities. In the 29th Street Mall of Boulder, the Euclidean zoning adopted in 1981 was the main tool, which did not have enough details or capacity to envision a project in the 2000s with such a complex context. The city of Boulder did not choose to revise the zoning or other regulatory tools for this site. As one of the interviewees mentioned: “ T hey could put a moratorium on it to re examine the zoni ng but [an intervention like this] it’s a big deal.” If planners and cit ies have the intention to create a strong regulatory system for achieving environment al values, they need to act more boldly where it is obvious that environmental values will not be a chievable by regular procedures and public engagement. In fact, cities have legal options to revise zoning and other tools before such redevelopment projects. Design guidelines : Design guidelines were intended to cover shortcomings of zoning in regulating actual shape and character of buildings in their neighborhood contexts. They could also override zoning rules by regulating form qualities with more specifications . In some cities , design guidelines r emain very brief and peripheral; in some others, they c an actually be an important supplementary regulation where Euclidean zoning does not provide sufficient fine scale rules. Design guidelines are an effective tool to inject discretionary mechanisms in relation to environmental and social justice values. Tal en (2012) argues that one of the main problems of zoning is the lack of fine scale rules. Design guidelines fill this gap. In fact, Formbased Codes, are a combination of zoning and design guidelines. It should be noted that design guidelines are supposed to be visionary and regulate future changes. In Boulder, the design guideline is not visionary and does not provide a clear path. It just fixes the current status of the site and as a result becomes a site plan rather than a guideline. Whereas, the design guideline in Belmar provides significant fine scale rules for the current and future development. To summarize, design guidelines provide a great opportunity for controlling design details and microclimate variables. Design guidelines can be customized reg ulations for downtowns or specific areas and as a result they can potentially guarantee some qualities. Cities can improve public space qualities with detailed design guidelines. Since, cities have authority in reviewing the design guideline of a

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187 project as an inherent part of application review process, guidelines could be an opportunity to overcome some conflicts among developers, citizens, and planning objectives. Public financing: Another choice that cities need to make is partnership with developers t hrough public financing mechanisms, like TIF. For making such decisions, cities need to consider issues around ownership and the developers. If agreeing on TIF leads to a form of partnership that enhances a city’s negotiating and supervising position, then it is a reasonable choice. The City of Lakewood was able to agree on a significant TIF. Boulder’s case was different, since the owner was a big corporation that was also the developer. City council members, citizens, and the City saw TIF as a handout to a corporation. It is not easy to argue what would have happened if the City would have agreed on a $80 million TIF. It is likely that TIF would have strengthened the City’s hand in the negotiations. Condemnation/Ownership factors : Managing ownership conflic t in large and flagship projects such as these is a gamechanging factor. Ownership becomes a deeper challenge particularly when the land economy is intense and the main owner is a big corporation. In such cases, similar to Boulder’s, defining a very fine scale and comprehensive regulatory system is particularly essential. R egulatory deficiencies in these contexts can cause profound problems and condemnation is not easy. In the case of Boulder, the intense local economy has created more sensitivity around r edevelopment projects , w hereas in Belmar the depressed economy of the city (in the early 2000s) created a more pro growth environment. The booming economy in Boulder incentivize d retention of properties in a more aggressive pursuit of profit. This complica te d the conflict between parties . In particular, resolving the ownership conflict was an obstacle. In contrast, the city of Lakewood became a partner of the developer and investors to redevelop the land. With a strong vision and motivation, they were able to go through the condemnation process and gain control of the land and design. That being said, the ownership conflicts in Belmar were not as complex as in Boulder. Final Take Aways The design strategies for improvement of urban microclimate are common s trategies with creating a walkable city. In fact, the strategies that FBCs are offering for a good urban design, such as building frontage and landscaping standards, hand in hand with microclimate management. That being said, heat mitigation deserves to be one of the main principles of design and planning

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188 strategies. The more important question is how cities can manage development processes to achieve successful projects that address environmental and social values. Hoch ( 1996) argues that the pragmatic approach to defining the best planning choice can benefit from evaluation of successful projects or best practices to find the important factors. These lessons might be generalizable for other similar situations. The analysis of development management in relation to heat mitigation fits in this category. The themes I introduce in this paper show how planners can improve development management in relation to intended outcomes. Connecting findings to theory and the literature, conflict in a major project like Belmar or 29th Street Mall is inevitable. Conflict arises in agreeing on visions and goals by developers, cities, citizens, and owners. As Campbell ( 1996) demonstrated, rea ching sustainability goals requires managing different types of conflicts such as property, resources, and development. He raised the question of “whether planners are likely to be leaders or followers in resolving economic environmental conflicts.” He encourages planners to play a more active role in managing the conflicts rather than mediating the controversy as an outsider. The findings here shed light onto how planners can approach these conflicts and what solutions or tools may be utilized to achieve t he goals. What I found in these two projects was that in Belmar the city effectively managed the conflicts regarding financing of the project, ownership obstacles, and laying out the vision through new regulations. Whereas in Boulder, the conflict was not managed effectively and resulted in a long and controversial procedure that failed in addressing climate related issues. A big corporate mall developer may not have common values with planning staff in setting goals for environmental or social values. In such situations, I suggest using the five tools identified here to effectively reach the goals of good urban design (presented in Figure 74). Local politics, public participation, and local economics affect the development managem ent procedures and ultimately have a strong control on project outcomes. The findings show that planners need to create an effective process but they also need to create strong visions, and improve regulatory tools such as zoning and design guidelines before starting a major project.

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189 Figure 74 Five factors in the development management process that matter for microclimate management Urban Vision Land Use and Building Form Controls Design Guidelines Public Financing Ownership & Condemnation Development Management Microclimate Management

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201 VII. APPENDIX A: INTERVIEW QUESTIONS This is a long list of possible questions. Depending on the role of the person in the project, the questions might be altered. 1. A brief explanation of the project and its context. 2. How did City s tart the project? 3. Who are the main parties involved in the Belmar project? 4. What was your role? 5. How did City choose the developer and the consultant? 6. What was the role of the planning staff in City? 7. Who was on the team? How was the team formed? What kind of skills or specialties the team had? How would you characterize the team expertise? Why that expertise? How did it work? 8. Expertise of the team. 9. Did you follow any specific planning approach in the design process of Belmar? (form based code, New Urbanism?) 10. How important your background was for a new urbanist model? 11. How was the public participation process? 12. Did you hear/experience any highlights/conflict from the process or the meetings? 13. What do you think about the quality of plan? 14. Different roles of the team and who had the most influential role. 15. What was the process of getting approval for the plan? 16. How the public participation and meetings were handled? How did pud/zoning type influence the project? 17. How did they use the flexibility allowed by pud? 18. How did pud influence the design review process? 19. Their relationships with city staff or boards? What was the role of design review boards? 20. How did the process and the relationships influence the outcome?

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202 21. How did the design guideline influence the project? 22. Who wor ked on the design guideline? How did you decide about the items of the design guideline? 23. How was the design guideline shaped? 24. What was the main resource of borrowing the design guideline principles? 25. Did City require a specific quality in the project? 26. How were the parking landscaping standards shaped? 27. Where did you get the design ideas? 28. How did the ideas emerge? 29. Did you have a specific person that led the design? 30. Did you have a specific process through which the ideas emerged? 31. What else is distinct or impor tant in the project that influenced the microclimate of the site? 32. Alternative plans? What was the major alternative plan? What did you have on the table or in your mind? 33. How did you decide about the street pattern? Why grid? Why having a main corridor? 34. Did the history of conflict or trust affect the project? 35. What do you think about the regulations and standards for building height? Who did decide about the building height? Why? 36. What is microclimate? Can you tell me some parameters in the built environment that affect urban microclimate? 37. Did you/the team/planning department/design review board/consultant consider one of these elements in the project? 38. If they consider something, for example, designing a plaza, how did the parties decide about those details? 39. W hat was the main challenge of the project? 40. How did you decide about trees and their costs and benefits? 41. What do you know about 29th street mall project? 42. Why do you think in Belmar we have more trees than Boulder 29th?

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203 VIII. APPENDIX B: ANALYSIS OF REGIONS AND SCENARIOS Wind and Temperature Region 1 Temperature Wind 29 30 31 32 33 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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204 IX. Region 2 Temperature 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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205 Wind 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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206 Region 3 Temperature Wind 29 30 31 32 33 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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207 Region 4 Temperature Wind 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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208 Region 5 Temperature Wind 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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209 Region 6 Temperature 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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210 Wind Reg ion 7 Temperature 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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211 Wind 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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212 Region 8 Temperature Wind 29 29.5 30 30.5 31 31.5 32 32.5 33 33.5 34 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation

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213 Mean Radiant Temperature Region1 Region 2 0.8 1 1.2 1.4 1.6 1.8 2 H11 H12 H13 H14 H15 H16 H17 H18 H19 BuildingHeight Combined Existing StreetDirection Vegetation 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario

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214 Region 3 Region 4 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario

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215 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario

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216 Region 5 Region 6 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario

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217 Region 7 Region 8 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario 20.0 30.0 40.0 50.0 60.0 70.0 80.0 H 7 H 8 H 9 H 10 H 11 H 12 H 13 H 14 H 15 H 16 H 17 H 18 H 19 H 20Chart Title Height Scenario Existing Scenario