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Building integrated photovoltaics

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Title:
Building integrated photovoltaics energy shifting as a new strategy for architects
Creator:
Finlaison, Carolyn D
Publication Date:
Language:
English
Physical Description:
60 leaves : ; 28 cm

Thesis/Dissertation Information

Degree:
Master's ( Master of Architecture)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
College of Architecture and Planning, CU Denver
Degree Disciplines:
Architecture

Subjects

Subjects / Keywords:
Building-integrated photovoltaic systems ( lcsh )
Architecture and energy conservation ( lcsh )
Architecture and energy conservation ( fast )
Building-integrated photovoltaic systems ( fast )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 59-60).
General Note:
College of Architecture and Planning
Statement of Responsibility:
by Carolyn D. Finlaison.

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|University of Colorado Denver
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Auraria Library
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
57708331 ( OCLC )
ocm57708331
Classification:
LD1190.A72 2004m F56 ( lcc )

Full Text
BUILDING INTEGRATED PHOTO VOLT AICS:
ENERGY SHIFTING AS A NEW STRATEGY
FOR ARCHITECTS
by
Carolyn D. Finlaison
A thesis submitted to the
University of Colorado at Denver
in partial fulfillment
of the requirements for the degree of
Master of Architecture
2003


This thesis for the Master of Architecture
degree by
Carolyn D. Finlaison
has been approved
by
5 -20/03
Date
Finlaison, Carolyn D. (MARCH, University of Colorado at Denver)
Building Integrated Photovoltaics: Energy Shifting as a New Strategy for Architects
Thesis directed by Assistant Professor Kat Vlahos


ABSTRACT
BIPV projects are a new phenomenon incorporating photovoltaic cells into
one or more of the exterior surfaces of the building envelope. By enmeshing PV
panels with the building skin, this material becomes part of the building, affecting
aesthetics, thermal qualities and the cost of the project. Synergy is the result, a
condition where the total effect is greater than if the building elements remained
separate. By finding synergistic solutions, architects offer an elegant and
economizing design that is more appealing to clients of the price sensitive grid-tied
market. The central problem is that multiple factors compete for the same building
envelope location and BIPV synergy may be lost. Envelope limitations may require
architects to sacrifice panel efficiency, desired aesthetic, or may even force the
decision for PV not to be included in the project. To ease this tension, PV can be
integrated with a suitable adjacent building envelope and the electricity transferred
back to the primary building. This concept, coined energy shifting, was tested at a
site in Boulder, Colorado. The question was whether the energy shifting strategy,
matching the load of one building with PV integration on another, would have
benefits.
For the study, a low energy case was simulated in Energy 10(1.4) that
reduced total building load by 44% to 442,114 kWh and reflected the hourly load
profile for the library. A site analysis produced 3 suitable PV sites: (A) on the
Boulder Public Library entrance vestibule, (B) on the Boulder Public Library south
wall and (C) on an adjacent building roof (energy shifting). The PV arrays annually
produce 2660 kWh (<1% of library load), 9701 kWh (2.3% of the library load) and
23,887 kWh (5.7% of the library load), respectively. The panel size and type, tilt,


and total square footage of the array were all chosen to maximize yield/limit
sellback while manifesting the best integration with the given site.
All three strategies provided benefits beyond the energy produced by the
panels. Strategy A, an architecturally pleasing, naturally integrated design, shaded
the vestibule producing a savings in energy cost over time. Strategy B decreased
glare though the thermal, and therefore, economic savings were negligible. Strategy
C (energy shifting), a large simple roof-integrated system, had an economic
advantage since the installation was timed with a needed roof replacement,
displacing materials and lessening the initial cost of including PV.
Energy shifting provided flexibility in design, allowing for greater
synergistic benefits in this study. A broad concept that is applicable in a wide range
of contexts, energy shifting can be added to the list of strategies that assist
designers. Architects should continue to look for synergy between the building
envelope and PV elements; however analysis should not be limited to one building
envelope.
Keywords: photovoltaics -1; building integrated -2; grid-tied -3; architectural
strategies -4
This abstract accurately represents the content of the candidates thesis. I
recommend its publication.
Signed
Kat Vlahos


ACKNOWLEDGEMENT
I regard it as the foremost task of education to insure the survival
of these qualities: an enterprising curiosity, an undefeatable spirit,
tenacity in pursuit, readiness for sensible self denial, and above all,
compassion.
Kurt Hahn
This thesis, an educational experience that far exceeded my expectations, was
possible with the generous time and support from:
The University of Colorado at Denver:
I would like to thank my advisor, Professor Kat Vlahos and the members of the
thesis committee: Professors Jake Frankhouser and Barbara Ambach. The College
of Architecture and Planning: in particular Professors Keith Loftin, Luis Summers
and John Prosser. In addition, I thank the Richard L. Crowther Scholarship Fund for
financial support during my thesis preparation semester.
The Community:
Thank you to the ALA Committee on the Environment (COTE), American Solar
Energy Society (ASES), Colorado Renewable Energy Society (CRES), Doug
Balcomb at the National Renewable Energy Laboratory (NREL), Bill Boyes and
Mark Koschade at the City of Boulder, AEC (Caroline Clevenger), Architect Vem
Sieceroe, ENSAR, and the staff of the Boulder Public Library and the West Senior
Center.
Lastly, I thank my family and friends. In particular, I thank Ulla Lange for her
collaboration, Renee Neswadi for her editing and most of all, Michael Lynn for his
editing, financial support and encouragement.


CONTENTS
Figures.................................................... vii
Tables..................................................... viii
CHAPTER
1. INTRODUCTION.................................... 1
Background..................................... 1
Hypothesis......................................4
Theoretical Framework...........................5
Summary.........................................7
2. REVIEW OF LITERATURE..............................8
Emergence of Utility Interactive BIPV.......... 8
Design Implications............................11
Summary........................................15
3. PROCEDURES AND TECHNICAL RESULTS.................16
Method.........................................16
Site...........................................17
Building Load..................................19
PV Simulations.................................22
Summary........................................24
4. FINDINGS: DESIGN STRATEGIES (3)
25


(A) An Aesthetic Feature
25
(B) Living with Signs on the Wall.......... 26
(C) Energy Shifting, a New Strategy........ 28
Comparison of Strategies................... 29
Summary.................................... 32
5. CONCLUSION................................... 33
Implications of Study...................... 33
Application for Other Contexts..............34
Design Decision Making......................35
Summary.................................... 37
APPENDIX..............................................39
A. BACKGROUND INFORMATION....................... 39
B. DATA COLLECTION.............................. 43
C. BP LIBRARY ENERGY 10 SIMULATION.............45
D. WS CENTER ENERGY 10 SIMULATION..............50
E. STRATEGY COMPARISON.......................... 54
GLOSSARY.............................................. 56
REFERENCES
58


FIGURES
Figure
1.1 Non-integration vs. integration.....................................2
1.2 Energy shifting concept............................................3
1.3 Site map...........................................................6
2.1 Policy, resource and rate drivers..................................9
2.2 Comparison of PV array outputs at 40 latitude....................13
2.3 Integrative approach to PV design.................................14
3.1 Method for comparative study......................................17
3.2 Site analysis.....................................................18
3.3 Potential PV sites................................................18
3.4 Average hourly profile for BP Library in kW.......................21
3.5 Simulated PV output for strategy (A)............................. 23
3.6 Simulated PV output for strategy (B)............................. 23
3.7 Simulated PV output for strategy (C)............................. 23
4.1 PV integration with entrance vestibule of the library.............25
4.2 PV integration as shading devices on the south facade of the library.... 27
4.3 PV integration with roof of the senior center.....................28
4.4 Overview of comparison of three BIPV strategies...................30


TABLES
Table
2.1 Architectural Criteria.........................................12
4.1 Architectural Criteria Comparison of Three BIPV Strategies.....30
5.1 Principles of BIPV for Architects..............................36


CHAPTER 1
INTRODUCTION
Give me the splendid silent sun with all its beams full dazzling.
Walt Whitman
Background
Recent advances in photovoltaic (PV) technology, coupled with a plethora
of creative design decisions, have ushered in a new wave of possibilities in
architecture. Harvesting energy from the sun is an ancient practice and is well
documented as passive solar design (Perlin & Butti, 1980). Since the 1950s,
active solar design, the use of PV cells to convert the suns energy to a useful
form of electricity, has also been well documented (Perlin, 1999) (Green, 2000).
The emergence of building integrated photovoltaic (BIPV) projects, however, is a
relatively new phenomenon.
BIPV projects incorporate photovoltaic cells into one or more of the
exterior surfaces of the building envelope. Instead of placing PV panels on a
building, the panels are enmeshed with the building skin. The distinction appears
to be minor, but the architectural consequences are significant. This enmeshment
allows the material to become part of the building, affecting the aesthetics,
thermal qualities, and cost of the project.
The building envelope is the canvas for BIPV. When the building is
viewed as a container with solid and semi-solid surfaces penetrated by openings,
the architect selects materials appropriate for the design intent. PV becomes a new
material on the palette, a solid panel acting as a shading device, a semi-
transparent panel as a window, or skylight. As Figure 1.1. demonstrates,
1


photovoltaics become integral to the design. In Roof A, two solid elements, a roof
covering and a PV array, are one on top of the other. In Roof B, the panel is the
roofing material, as it becomes the solid surface of the building envelope. The
displacement of the roof element not only alters the aesthetic of the building, less
material is used. Moreover, the PV panels are now part of the roofing system
impacting the thermal qualities of the project. Synergy is the result, a condition
where the total effect (energy produced plus displaced materials plus thermal
benefits) is greater than if the building elements remained separate.
Figure 1.1. Non-integration vs. integration.
The synergy of BIPV has notable value in the price sensitive grid-tied1
market. PV systems are rarely cost effective when compared with conventional
utilities; however, when benefits beyond the energy produced by the panels are
realized, PV systems are more competitive. By finding synergistic solutions,
architects are able to offer an elegant and economizing design that is more
appealing to clients in this market. 1
1 Grid tied systems (utility interactive projects) are PV systems connected to the electric utility
with a buy/sellback agreement established. Autonomous (off-grid) and grid-tied with battery back-
up systems operate with different parameters.
2


The Problem
By finding the most suitable location for integration (good orientation,
panel tilt, no obstructions), PV output is maximized and the client receives the
most return on their PV investment. At the same time, other factors such as
thermal performance, daylighting, views and ventilation are being considered in
building envelope design. As the building takes shape, it may be discovered that
an interior space requires more daylight or the panel tilt conflicts with building
form; PV is then relocated or repositioned. The interaction between PV and other
design elements either produces synergy or watered down trade-offs occur that
are far from the original intent.
The central problem is that multiple factors compete for the same building
envelope location and BIPV synergy may be lost. Envelope limitations may
require architects to sacrifice panel efficiency, desired aesthetic, or may even
force the decision for PV not to be included in the project. In these cases, the
tension between conflicting elements needs to be released. If the architects scope
of concern is broadened to include adjacent buildings, new relationships can be
investigated. Looking beyond one building envelope, architects can search for
new PV locations finding synergistic benefits for their clients. When the potential
for synergy within one building envelope is limited, another in close proximity
can be connected to it.
This concept the author has coined energy shifting
and is depicted in Figure 1.2. Energy shifting is the
matching of the energy needs of one building with PV
integration on another. It is a physical shift of energy
from one building to another, and it is a mental shift
that questions design parameters. In conventional
Figure. 1.2. architectural projects, spatial and ownership
boundaries limit design inquiry. Energy shifting challenges architects to literally
3


think outside the box. The success of current BIPV projects hinges on the
integration of PV cells into the building envelope, but design should not be
limited to one building envelope.
Significance of the Study
Energy shifting increases the number of potential PV locations, giving
designers more flexibility and opportunity to discover BIPV synergy for clients.
Although tested at a specific site, there is a generalizability about this concept that
allows it to be applicable in other contexts. It is a broad concept that supports the
ease of PV integration, leading to greater PV acceptance and adding value to
buildings.
Hypothesis
The following thesis questions the design assumption that BIPV synergy
must be found within the confines of one building envelope2. If the scope of the
analysis is expanded beyond one building envelope to include adjacent buildings,
the thesis is that new market solutions will surface. The primary objective is to
evaluate the performance characteristics and relative significance of energy
shifting between buildings utilizing BIPVs. The hypothesis is:
If BIPV energy shifting is the design strategy,
then architectural/market benefits3 will be achieved.
It is the authors premise that by focusing on the relationship between hourly
building load and multiple building envelopes, the greatest benefits will be
realized. It is postulated that in a controlled study, energy shifting will produce
BIPV synergy that will have architectural/market value equal to or greater than
the strategies found within the primary building envelope.
2 PV panels that are part of the landscape (carports, etc.) are not included in this study.
3 See glossary for definitions of hypothesis terms.
4


Theoretical Framework
The new BIPV strategy, energy shifting, was tested at a chosen site in
Boulder, Colorado (see Figure 1.3. for site map). The 1992 addition to the
Boulder Public Library and its surroundings provided a good test case. The
original library design reduced electric demand, maximized efficiency, and
harvested site energy (passive); however, photovoltaics were not part of the
energy performance plan. It is assumed that a decade later, PV integration is re-
assessed. An expanded site analysis enabled adjacent buildings to be considered
in the investigation. Building load analysis and PV simulations aided in a
systematic study, leading to the generation of three synergistic BIPV strategies.
The evaluation of the three BIPV strategies was comparative in nature.
The evaluative framework established was based on literature review and devised
by the author. In order to maintain consistency, all synergistic strategies were
compared in the same four ways: degree in which Architectural Criteria was
achieved, economic impact, environmental impact and potential for innovation /
demonstration for future projects.
Limitations
1. The over-riding political, social and economic factors influencing
architectural decisions were considered in general terms.
2. Ballpark estimations were used in the Energy 10 building load simulation
and cost analysis; in-depth simulation and analysis was beyond the scope
of the study.
3. PV installation and utility connection issues were not investigated at
length.
These items were not arbitrarily excluded, rather an effort was made to narrow the
focus and place emphasis on design.
5


Figure 1.3. Site map of study area: north of Arapahoe and east of 9th Street in
Boulder, Colorado.
6


Summary
BIPV projects are a new phenomenon incorporating photovoltaic cells into
one or more of the exterior surfaces of the building envelope. By enmeshing PV
panels with the building skin, this material becomes part of the building, affecting
aesthetics, thermal qualities and the cost of the project. Synergy is the result, a
condition where the total effect is greater than if the building elements remained
separate. By finding synergistic solutions, architects offer an elegant and
economizing design that is more appealing to clients of the price sensitive grid-
tied market. The central problem is that multiple factors compete for the same
building envelope location and BIPV synergy may be lost. Building envelope
limitations may require architects to sacrifice panel efficiency, desired aesthetic,
or may even force the decision for PV not to be included in the project. To ease
this tension, PV can be integrated with a suitable adjacent building envelope and
the electricity transferred back to the primary building. A site in Boulder,
Colorado was chosen to test this concept, energy shifting. The question was
whether the energy shifting strategy, matching the load of one building with PV
integration on another, would have benefits. To determine if energy shifting has
architectural / market value, it is necessary to understand the context in which
BIPV projects are operating. In chapter 2, reviewed related literature sets the stage
for a better understanding of the importance of this study and its potential impact
on the field of architecture.
7


CHAPTER 2
LITERATURE REVIEW
If the 19th century was the age of coal and the 2(fh of oil,
the 21st will be the age of the sun.
Randall Thomas
Emergence of Utility Interactive BIPY
The surge of utility interactive projects, renewable energy intermixed with
mainstream supply, is a relatively new phenomenon signaling a change in the
energy industry. Conventionally, energy companies generate electricity in a large
centralized plant, be it coal, nuclear, hydro or gas, and transmit it through a high
voltage system to substations and the end-user. These plants are very capital
intensive and create large environmental impacts. Political and economic forces
are now favoring smaller scale projects and are moderately supporting on-site
production (see Appendix A: The Changing Energy Industry for a more detailed
account of events). In short, there is an undeniable trend towards distributed
generation (Smeloff & Asmus, 1997) (Hirsh, 1999).
Activated by resource, policy or rate drivers (see Figure 2.1),
utility interactive (grid-tied) PV projects are surfacing in
specific regions. The Sacramento Utility District (SMUD) in
California provides a good example. After two decades of
nuclear energy problems, SMUD realized that a lack of
conventional resources was leading to higher demand charges and ultimately an
inability to meet their clients needs. Turning to distributed generation, SMUD
began installing utility-owned PV on customer roofs and feeding energy into the
local line (Osborn, 2001). A noteworthy example holding many lessons for
8


architects (see Appendix A: SMUD, A Case Study), this case also heeds a
warning. When PV is utility-owned and non-building integrated, the utility
company benefits, but the building owner may not. Working with individual
building owners, architects have a vested interest in shaping customer side of
the meter incentives that directly benefit their clients.
Resource Policv Electric Rate
Lack of conventional resources Utility Regulation High demand charges
Threatened imported supply e.g. RPS4 Customer Side Incentives
Renewable resource potential Owner Incentives e.g.Net-metering3
e.g. Tax, Grants Time of day rates3
Figure 2.1. Resource, policy and electric rate drivers.
Non-Inte grated PV Market
In some regions, individual building owners receive direct economic
incentives for investing in PV. By receiving a tax break/rebate or compensation
from the utility, the high cost of PV can be offset. In a net-metering arrangement,
the owner is able to watch their meter spin backwards, being paid for energy
exported to the grid. Even with a long payback period, the number of years it
takes for the PV system to pay for itself, this is appealing to some clients. Many
of these grid-tied projects are non-integrated and heed another warning. Dotting
the landscape, non-building integrated projects are shaping public perception.
Architects have a vested interest in influencing this perception, promoting the
aesthetic value of building integration and the importance of design.
4 See Glossary
9


High-End BIPY Market
Some architects are conveying the aesthetic potential of BIPV by focusing
on one-time high design projects (see pvdatabase.com for the most complete
source of grid-tied BIPV projects). Innovatively integrating PV by using new
amorphous silicon (thin-film) technology for example, architects are able to
convince clients that PV will positively impact the buildings image. Realizing
BIPVs are not attractive because of the payback time frames, architects and
planners chose to look to design and environmental consciousness as the true
value of these systems (Markvart, 2000). This brought about a marked change
demonstrating the added value of BIPV. Architects experimenting with new
forms of integration, are finding synergistic benefits such as thermal advantages,
daylighting interactions and cost savings through displaced materials. Although
the high cost of PV integration is a barrier for widespread growth, select projects
in Europe, Japan, Australia and the United States are making an architectural
statement.
New Market Potential
Building on lessons learned in the high end BIPV market, architects are in
a unique position to develop design bringing PV to a wider audience. The price of
PV is dropping (Thomas, 2001), but a threshold has not been reached where PV is
directly competitive with conventional utilities. Small benefits, for example a PV
awning that shades pedestrians entering a building, make PV more attractive.
Those benefits that diminish cost, like displaced roofing materials, or decreased
thermal gain and therefore, utility costs over time, have particular value. By
finding synergistic solutions, architects are able to offer an elegant and
economizing design that is more appealing to clients in the price sensitive grid-
tied market. The challenge is to get the cost of including PV into a reasonable
10


range so as to be considered by mainstream clients. To do this, architects must
consider the design implications inherent to PV integration.
Design Implications
Form
How PV will interact with the building form is a prominent architectural
concern. There are many site-specific examples of integrating PV into the form of
the building (see www.pvdatabase.com). Methods can be grouped into three
categories: roof systems, fagade systems, and sunshades (Thomas, 2001) (See
Appendix for illustration by Thomas). The International Energy Agency (IEA)
has established some guidelines to assist architects in integrating PV successfully
(see Table 2.1. for an overview). Although PV integration is site specific, general
concepts such as color, texture and size of panel challenge architects to consider
how the PV system will relate to the total image of the building and its context.
The guidelines are reasonable and serve as a useful tool for designers.
PV Output and Building Electrical Load
At 40 north latitude, a south facing panel tilted at 40 will produce the
highest yield of solar energy, while altering the tilt / orientation will result in loss
of panel output. Figure 2.2. demonstrates the relationship between panel angle,
orientation and output at a given latitude. There is some room for movement here
since a small adjustment results in only a small percentage of energy loss
(Pearsall & Hill, 2001). However, the further from optimal that a panel is placed,
the greater the consequences. A guideline that architects can employ is to not vary
+/- 15 in tilt or orientation from optimal.
The size of the system is often dictated by the nature of the building,
shading, or owner preferences, but it can also be driven by electrical load
(Pearsall & Hill, 2001). For example, a zero-net electrical energy house has a PV
11


Table 2.1. Overview of Task VII Architectural Criteria (Scheon, et. al., 2001)
International Energy Agency, Task VIIBIPV Criteria for Architects
1. Naturally Integrated The PV system is a natural part of the building.
Without PV, the building would be lacking something the PV system
completes the building.
2. Architecturally Pleasing Based on a good design, does the PV system
add eye-catching features to the design.
3. Good Composition The colour and texture of the PV system should be
in harmony with the other materials. Often a specific design of the PV
system can be aimed at (e.g. frameless vs. framed modules)
4. Grid, Harmony and Composition The sizing of the PV system
matches the sizing of the grid of the building.
5. Contextuality The total image of the building should be in harmony
with the PV system. On a historic building, tiles or slates will probably fit
better than large glass modules.
6. Well-engineered This does not concern the watertightness of PV roof,
but more the elegance of design details. Have details been well-
conceived? Has the amount of materials been minimised? Are details
convincing?
7. Innovative New Design PV is an innovative technology, asking for
innovative, creative, thinking of architects. New ideas can enhance the PV
market and add value to buildings.
12


Position______Monocrystalline Panel
sw
s
lass
se
lass fr".-.. Optimum loss
lass
Adapted for 40 Latitude
from Thomas, 2001.
Figure 2.2. Comparison of PV array outputs at 40 latitude.
array that is large enough to generate as much energy in one year as the building
requires (Balcomb et al.). Since the energy is not necessarily produced at the same
time it is needed, a buy/sellback relationship is set up with the utility. Electric rate
can also influence the number of panels used. For instance, if there is no net-
metering law or a poor compensation for excess energy produced, the designer
may chose to limit the array so that no sellback to the grid occurs. When this is
the case, the hourly profile of the building becomes very important. If the load
dictates the number of panels, dummy panels may have to be used to finish out
integration. Moreover, load conditions can influence panel orientation. A
13


technique where panels are placed west of south (185-270 azimuth) to
compensate for high summer air-conditioning loads, is a possible strategy (Green,
2001). Similarly, an east facing array (90-175 azimuth) would be most suitable
for a high morning load.
Integrative Approach to Design
For a good integration that is elegant and economizing, all factors need to
be considered in the design process (see Figure 2.3.). Integration is not just a
melding of PV with the form of the building. Rather it is deeply embedding PV
into the systems of the buildings, interacting with the building envelope and
becoming a strong component of the energy performance plan. A well devised
methodology takes into account the nature of the building and the electrical load,
leading to the discovery of synergistic design solutions.
Building Envelope Energv Performance
thermal barrier site
ventilation passive solar
form + PV output = PV integration
daylighting efficiency
views demand
Figure 2.3. Integrative approach to PV design.
14


Summary
The energy industry is moving toward distributed generation and utility
interactive PV projects are surfacing as part of this trend. Architects have a vested
interest in shaping distributed generation, capturing economic benefits for their
clients and promoting the aesthetic value of BIPV. Even though the price of PV is
dropping, a threshold has not been reached where PV is directly competitive with
conventional utilities. Building on lessons learned in the high-end BIPV market,
architects can penetrate the price sensitive grid-tied market by offering elegant
and economizing designs that are appealing to clients. To do so, an integrative
approach is necessary that explores the regional conditions, the synergistic
potential within the building envelope, and the part that PV plays in the energy
performance plan for the building. A methodology based on an integrative
approach to PV design will be carried out in the following chapter.
15


CHAPTER 3
PROCEDURES AND TECHNICAL RESULTS
Method
A site in Boulder, Colorado (40.02 N Latitude, Elevation 5363 ft/1634 m)
was chosen to test this hypothesis (see Figure 1.3. or 3.2. for site map). The
53,000 ft2 (4924 m2) addition to the Boulder Public Library (BP Library) was
completed in 1992. For the purpose of studying site and building load, elements of
the 1992 design process were accepted as given conditions (see Appendix B for
description of building orientation, footprint, layout, form and other factors).
Using data collected from utility bills, an Energy 10-PV reference case
was generated that reflects the total annual building load for the existing library
on the site. After further investigation through observations, interviews and
computer modeling, a low energy case was generated that improved energy
performance and reflected the hourly load profile for the building. The process
was repeated for a second building to ascertain the potential for energy shifting.
Three synergistic BIPV strategies were then created that matched the library load
profile, two on the primary building and one on an adjacent building. All
strategies were evaluated and compared in four ways: (1) Architectural Criteria
(see Table 2.1, page 13) (2) economic impact, (3) environmental impact and (4)
innovative/demonstration for future projects (see Figure 3.1). The potential for
energy shifting was then determined and the context in which it is most
appropriate was identified.
16


Method
Aiclutcetural Criteria
* Naturally Integrated
Architecturally Pleasing
Good Composition
Grid, Harmony
Contextuality
Well-engineered
Innovative New Design
Demotivation for the Futute
_____________i
Figure 3.1. Method for comparative study.
Site
Key site issues are solar access and availability of surface area. The library
has good exposure to year-round sunlight on the roof, south wall and in the
parking lot. The area is free of obstructions except for the deciduous tree on the
south side of the library (see Figure 3.2.).
Looking beyond the building envelope, it was noted that there were
several potential sites in the immediate area (see Figure 3.3.). Sites 4 and 5 were
excluded as not appropriate for the study5. Site 6 was also excluded since
mounting panels on the non-uniform canvas roof would be difficult and would not
provide any synergistic benefits. Integration with the roof clerestories was
considered as part of Site 2. It was determined that PV integration was most
viable on the senior center south roof6 (Site 3), the BP Library south facade (Site
2) and the entrance vestibule (Site 1).
5 The hypothesis is limited to building envelope integrations, excluding independent structures.
6 Chosen for its southern exposure and potential synergistic benefits (roof in need of replacement).
Comparative
Study of
(3) Integrated
Strategies
Economic Impact
Environmental Impact
C02 Emissions
17


Figure 3.2. Site analysis (above) and Figure 3.3. potential PV sites.
18


Building Load
BP Library Reference Case
The energy performance of the BP Library is better than other educational
buildings. The design reduces demand through light sensors, maximizes
efficiency through a detailed maintenance and upgrade plan and utilizes
daylighting techniques. Still, total annual electric use reaches 860,200 kWh (see
Appendix B).
In generating a reference case using Energy-10(1.4) software, attention
was given to ensure that the simulated annual electric load (752,618 kWh)
roughly matched the actual annual load noted on utility bills. Energy 10
simulation summary, total energy use and electric use breakdown can be found in
Appendix C. Electric use is realistic, accounting for scheduled plug loads, lights,
exhaust fans and seasonal weather variations.
Optimizing Energy Performance
Once the reference case was established, it was prudent to consider
strategies to further optimize energy performance. This ensured a better match of
energy supply and demand and demonstrated a best use of dollars spent
approach. PV is currently expensive and it makes little sense to incorporate PV on
a building with excessive energy loads. As mentioned, the BP Library has better
energy performance than typical educational buildings; however, there are some
interventions that would improve performance.
1. Shading Although the natural light creates a welcoming environment, the
evaporative cooling system is at maximum capacity to meet the load during
summer months. Providing permanent shading on the entrance vestibule
would lessen the cooling load. Additionally, increased shading on a portion of
19


the south windows would decrease the glare on bookshelves and workstations.
This would not impact the load; however, it would aid in occupant comfort.
2. Lighting Changing out exit lights to LEDs would lessen load. In addition,
combining upgraded fixtures (e.g. dimming ballasts) with a new control
strategy would help the library meet lighting demands. Currently, the library
has an extensive computer program to monitor HVAC schedules, but the
lighting program relies on manual input. An investment in new technology
that closely monitors lighting would decrease cooling and electric loads.
3. Energy Efficient Equipment In the age of information, the other category
of electric use (see Appendix C: electric use breakdown graph) is typically
high due to the use of photocopiers, computers and communication. By
upgrading to more efficient equipment, the library may be able to lessen this
load.
4. Other design interventions include an improvement in insulation, thermal
mass, ductwork and a reduction of heat/cold conducting metal furnishings.
Low Energy Case
By optimizing energy performance through design interventions7 to the
reference case, a low energy case was established. The total annual electric load
(422,114 kWh), a 44% reduction in comparison to the reference case, was used in
calculations hereafter. The Energy 10 simulation results are in Appendix C.
Simulation of Hourly Load Profile
For a matching of PV supply and demand, it is not only valuable to
identify the total electric load, but also the time of day when demand occurs.
7 Only those design interventions included in Energy 10 were used to establish the low energy
case.
20


Based on highest occupancy hour and HVAC schedules, it was estimated that the
average daily peak electric load is at 2 pm.
Figure 3.4. Average hourly profile for BP Library in kW.
If the orientation of the array is based solely on the timing of the load, the
most optimal array would be southwest for the library (see Figure 3.4.). A
southwest array for the library load in theory makes sense, but in the preceding
site analysis, it was noted that there are no southwest potential sites available. A
designer could reassess the site and discover a creative southwest integration, but
there are adequate south and southeast facing sites that run in line with the
orientation of the building. Since building integration is a primary concern and
maximum PV output is true south ( 15), investigation continued within these
parameters. The following three simulations are within the true south ( 15)
limits. The panel size and type, tilt, and total square footage of the array, were all
chosen to reflect the best integration with the site.
It should be noted that the average hourly load profile for the senior center
is quite different (see Appendix D). With a peak load between 10am and 11 am,
an east facing array would be more suitable. This is an important point, for it
21


establishes the benefit of energy shifting. If the senior center integrated PV on the
south roof was matched to the senior centers load, a large sellback would occur.
This would not be economical in the region of study considering sellback rates.
PV Simulations
Simulation (A) South Facing Facade Integration
(60) 27W amorphous silicon (thin-film), semi-transparent
modules (10% light transmission)
Panel Dimensions: 47 (1.2 m) x 23.6 (0.6 m)
Tilt 35, Orientation S (175 azimuth)
Total Square footage: 465 ft2 (43 m2)
PV Output: 2660 kWh (see Appendix C: PV summary page for extended results)
Simulation (B) Sunshade South Wall Integration
(60) 100W poly-crystalline modules
Panel Dimensions: 37.8 (0.96m) x 33.8 (0.86m)
Tilt 40, Orientation S-SE (168 azimuth)
Total Square footage: 535 ft2 (50 m2)
PV Output: 9701 kWh (see Appendix C: PV summary page for extended results)
Simulation (C) South Facing Roof Integration
(50) 300W poly-crystalline modules
Panel Dimensions: 74 (1.89m) x 50.4 (1.28m)
Tilt 20, Orientation S (180 azimuth)
Total Square footage: 1305 ft2 (121 m2)
PV Output: 23,887 kWh (see Appendix D: PV summary for extended results)
22


BP Library 2, AutoBuild Shoebox
1.2'
1.0*
10.8-
L
0.2-
PV Output fiver aoe Pally Pronto (Low Enenw Case). Total 2659.6 KWi
0.0H1
0 6
RiqK dtek to changt propfTit_
J=l-
12
Hour of Day
Figure 3.5. Simulated PV output for strategy (A).
Figure 3.6. Simulated PV output for strategy (B).
Figure 3.7. Simulated PV output for strategy (C).
23


Summary
A low energy case was simulated in Energy 10-PV that a) reduced total
building load by 44% to 442,114 kWh and b) reflected the hourly load profile for
the library, peaking at 2 pm. An expanded site analysis produced three suitable
PV sites, one on the entrance vestibule of the library, one on the south wall of the
library and one on the roof of the senior center (energy transferred back to the
library). All three simulations are a good match of hourly supply and demand,
limiting energy sellback to the utility. The PV arrays annually produce 2660 kWh
(<1% of library load), 9701 kWh (2.3% of the library load) and 23,887 kWh
(5.7% of the library load), respectively. The panel size and type, tilt, and total
square footage of the array were all chosen to maximize yield, while reflecting the
best integration possible with the given site. The design implications are discussed
at length in the following chapter.
24


CHAPTER 4
FINDINGS: DESIGN STRATEGIES (3)
(A) Aesthetic Feature
i^. In the first integration, amorphous silicon PV were added to the top
of the structure (keeping glass as substrate), altering the thermal and
illuminance qualities of the vestibule. Shading does not interfere with
tasks in the transition space and the semi-transparent panels diminish
direct sunlight, lessening summer cooling loads. The array produces 2660 kWh
annually meeting < 1 % of the buildings energy needs, all at the time of need.
Figure 4.1. PV integration with entrance vestibule of the library.
25


Advantages
1. Synergy (Lessens Thermal Load) Summer cooling loads were decreased as
direct south sunlight was diminished (panels allow 10% light transmission).
2. High Profile An aesthetic feature was integrated at a prominent location.
3. Good Use of Materials Thin-film technology was applied on top of existing
glass leaving an air gap.
4. Good Match of Supply and Demand Orientation of array fits library hourly
load profile.
Disadvantages
1. Size of Array Array limited by space of vestibule, and by luminance to
some extent.
2. Cost Custom work may be needed because of the unusual shape of the
vestibule.
3. Panel Efficiency Thin-film had lower efficiency than other PV technology.
(B) Living with Signs on the Wall
Similar to Strategy A, PV was integrated into the building
envelope of the BP Library (see Figure 4.2.). This time panels
act as sunshades on the south wall. The poly-crystalline panels
produce 9701 kWh of electricity, meeting 2.3% of the buildings
needs, with a good match of supply and demand. The panels have a synergistic
benefit decreasing glare from the direct sun while collecting energy. The impact
on thermal loads was negligible. The PV modules are supported by a metal
framework and are set at an angle of 40.
26


Figure 4.2. PV integration as shading devices on south facade of the library.
Advantages
1. Synergy (Daylighting) By decreasing glare, increased occupant comfort at
bookshelves and workstations was achieved.
2. Maximum Capacity The optimal tilt at 40 latitude was achieved.
3. Natural Integration Horizontal emphasis harmonized with library design.
Disadvantages
1. Obstruction The size of the array was limited to avoid shading by a tree.
2. Limited Dual Purpose The size of the array was limited in order to have the
panels act as shading devices.
27


(C) Energy Shifting, a New Strategy
The third strategy makes use of the adjacent building through
the replacement of roofing materials on the south facing roof
(see Figure 4.3.)- Integrated PV array mounting systems attach
tjje py moduies directly to the rafters with brackets, displacing
the conventional roof covering. This section of the roof is in moderate condition
and has not been replaced since project construction in 1978. Since the clerestory
extensions cast a shadow on the western portion of the roof late in the day,
dummy panels are placed here instead of solar panels. Ventilation and access to
the electrical connections is facilitated by the underside of the panels being
exposed to the attic. The electricity from this south-facing array is transferred to
the library, meeting 5.7% of the librarys needs at the time of use. This array is
not a good match with the senior centers energy demand and more sellback to the
utility would occur if the energy was not shifted next door (see page 53).
Figure 4.3. PV integration with roof of the senior center.
28


Advantages
1. Synergy (Displacement of Building Envelope Materials) A synergistic
benefit was realized by timing the integration with a needed replacement of
the existing senior center roof.
2. Large Array The unit cost of all PV electricity produced falls with
increasing array size because of economies of scale (Thomas, 2001).
Disadvantages
1. Tilt Not Optimal The 20 sloping roof was not optimal at this latitude which
resulted in a small loss in panel efficiency.
2. High Initial Capital Cost The large array had a high initial cost.
Comparison of Strategies
Given the regional characteristics of the study area, the challenge was to
develop three synergistic BIPV strategies that each offered an elegant and
economizing design for the library. The question was whether the energy shifting
strategy, matching the hourly electric load of one building with building envelope
PV integration on an adjacent building, would have advantages over the other two
strategies. A comparison of the strategies using the devised evaluative framework
is depicted in Figure 4.4.
Architectural Criteria
In Table 4.1, the three strategies are compared in the degree to which the
architectural criteria were met. Strategy A was the best choice for architectural
integration. It was the most architecturally pleasing and minimized materials by
utilizing existing glass. The details and material choice provided for a smooth
integration.
29


Comparative Study
Architectural Criteria
Strategy A
Demonstration tor the Future
All Three Strategies
Design
Comparative
Study of
(3) Integrated
Strategies
Economic Impact
Simple Payback in years
A B C
42 36 30
Net-present Value
A B C
($1,720) ($6,442) ($13,347)
Environmental Impact
Strategy C
Figure 4.4. Overview of comparison of three BIPV strategies.
Table 4.1. Architectural Criteria Comparison of Three BIPV Strategies
(see p. 14 for Architectural Criteria explanation)
(A) Vestibule (B)Sunscreens (C) Shifting
Naturally Integrated Y Y N
Architecturally Pleasing Y N N
Good Composition Y Y Y
Grid, Harmony Y Y Y
Contextuality N N Y
Well-engineered Y N N
Innovative New Design N N Y
Total 5 3 4
30


Economic Assessment
Using the payback method for a simple comparison, Strategy C was the
best choice. This was because the cost of displaced roofing materials was
subtracted from the initial cost of the system (see Appendix E for calculation).
However, when the net-present value method was used, Strategy A was the best
choice. This was because savings from the decreased thermal load became
Q
increasingly significant over time It comes down to clients needs. In this case,
reducing capital costs is more persuasive than savings over time.
Environmental Impact
Strategy C was the best choice for lessening C02 emissions8 9 because it is
the largest array. Implementing this strategy displaces 35,000 lbs of C02 annually
(see Appendix E for calculations). All three systems provide societal benefits by
reducing emissions in comparison to conventional fuels. Some benefits might
include a reduction in the cost of environmental clean-up from the fossil fuel
industry and less expenditure for health and safety issues related to emissions.
Environmental impact should not be overlooked as a selling point to the client,
particularly government agencies.
Innovation / Demonstration for future projects
All three strategies demonstrated innovation and are examples for future
projects. They are good BIPV strategies that integrate PV into the building skin
exhibiting synergistic qualities. This acquired know-how and experience is
important to the field of architecture. In addition, all strategies are highly visible
as an expression of the citys values and promote BIPV. Strategy C illustrates an
8 These methods provide data to compare the strategies in general terms; further analysis would
determine if a better outcome could be achieved than the author described.
9 C02 emissions are only one of many indicators that can be used to measure environmental
impact.
31


arrangement not typical in this country of linking the building load of one
building with PV integration on another.
Summary
Each strategy has its advantages and disadvantages. Comparing the three
strategies using the devised evaluative framework, it was determined that Strategy
A most satisfied the Architectural Criteria as an architecturally pleasing, naturally
integrated design. It had economic advantages because the integration shaded the
vestibule producing a savings in energy cost over time [NPV ($1,720)]. Strategy
B also provided shading with panels as sunshades, but the thermal savings were
negligible. Strategy C had an economic advantage since the cost of displaced
roofing materials ($13,000) were subtracted from the initial cost of the system. In
addition, this was the strategy with the largest array, displacing the highest
percentage of C02 emissions when compared to conventional fuels.
32


CHAPTER 5
CONCLUSION
The building envelope is central to BIPV because it is through the
displacement of building materials and the effect on the thermal qualities of the
building that benefits have been realized. As society transitions to a post-fossil
fuel economy, this synergy should be replicated allowing design to fully
contribute to the process. To do so, architects must literally think outside the box
and not limit design inquiry to one building envelope. By expanding parameters
to include the building envelope of adjacent structures, architectural / market
benefits arise.
Implications of Study
The hypothesis, that if BIPV energy shifting is the design strategy, then
architectural / market benefits will be achieved, opened the door for investigation,
In the study case, energy shifting provided flexibility in design. In Strategy C, a
large simple roof-integrated system had an economic advantage since the
installation was timed with a needed roof replacement, displacing materials and
lessening the initial cost of including PV. Although not cost effective under the
parameters established, it incrementally brought the cost of including PV into a
reasonable range for discussion. For instance, Strategy C would be economically
feasible with a grant of $12,000. The author urges the City of Boulder to also
consider the added value demonstrated in this integration. Besides the energy
produced and the synergistic benefit, this integration would be an expression of
the citys values, decreasing C02 emissions and promoting innovation. When the
senior center is renovated, all of the above factors should be considered in the
33


decision. Furthermore, valuing a life-cycle approach, Strategy A is also a
reasonable option.
Recommendations for Future Study
This study had the premise that the BP library was the primary building
and energy supply was matched to its building load. This led to the conclusion
that energy shifting is relevant since the senior centers load did not match the
array of Strategy C. By treating the two building loads as separate, an opportunity
for new potential was not examined. Namely, if the two building loads are
aggregated into one load, an energy plan for the area could be designed. This
analysis would take the energy shifting concept to the next level of research and is
recommended for future study.
Application for Other Contexts
Energy shifting is a broad concept that is applicable in other contexts.
Capturing the benefits of building envelope synergy will need to be investigated
with the specific goals of the project in mind. Energy shifting can become part of
an expanded site analysis and explored if there is merit. It can be added to the list
of strategies discussed in Chapter 2 that assist designers in striving to make PV
economical for the client. Energy shifting is most applicable when the client owns
multiple buildings. In this way, an energy plan can be drawn up for the site and
energy shifting analyzed without constraint. If the client does not own the
adjacent buildings, then a leasing agreement may have to be drawn up; a more
difficult task, but not impossible. SMUD (Osborn, 2001) and REMU
(Bouwmeester, 1999) are two utility companies that have set precedents with such
agreements.
34


Design Decision Making
Through casting a wide net in this investigation, it was discovered that
many factors influence architectural decisions. PV design is not simply
integrating PV with the form of the building. Instead, it is a negotiation of
multiple design elements, deeply embedding PV into the systems of the building.
It was discovered that Energy 10(1.4) is a valuable tool for predicting building
loads. Since it is through understanding the hourly load profile and building
envelope characteristics that lead to synergy with PV elements, this step becomes
critical. The Architectural Criteria set out by Task VII of the IEA is also a useful
tool for the design process. From the results of this study, the author recommends
five principles, in addition to the Architectural Criteria, to guide architects in an
integrative approach to PV design (see Table 5.1.).
As Markvart stated (2000), architects are among the group of
professionals that have brought about a marked change. By demonstrating the
value of integrating PV with the building envelope, these projects are shaping the
path of distributed generation. Energy shifting is a mental shift in thinking that
supports this future goal.
35


Table 5.1. Principals of BIPV for Architects
Principals of Building Integrated Photovoltaics for Architects
International Energy Agency, Task VII BIPV Criteria for Architects
1. Naturally Integrated The PV system is a natural part of the building. Without PV, the
building would be lacking something the PV system completes the building.
2. Architecturally Pleasing Based on a good design, does the PV system add eye-catching
features to the design.
3. Good Composition The colour and texture of the PV system should be in harmony with
the other materials. Often a specific design of the PV system can be aimed at (e.g.
frameless vs. framed modules)
4. Grid, Harmony and Composition The sizing of the PV system matches the sizing of the
grid of the building.
5. Contextuality The total image of the building should be in harmony with the PV
system. On a historic building, tiles or slates will probably fit better than large glass
modules.
6. Well-engineered This does not concern the watertightness of PV roof, but more the
elegance of design details. Have details been well-conceived? Has the amount of
materials been minimised? Are details convincing?
7. Innovative New Design PV is an innovative technology, asking for innovative, creative,
thinking of architects. New ideas can enhance the PV market and add value to buildings.
(IEA)
Additional Five Principles for Integrative Approach to PV Design
8. Regional Characteristics Do you understand the interactions of resource, rate and
policy in the area of the integration? Where can you go to receive updated information?
9. Energy Performance Is the PV placement deeply embedded in the energy performance
plan for the project?
10. Building Envelope Synergy Have you considered how PV can have a dual purpose in
the building envelope? Is PV deeply embedded into the building envelope design?
11. Cost Analysis Have you gone beyond the simple payback method and demonstrated the
added value of BIPV?
36


Summary
Energy shifting, matching the hourly electric load of one building with PV
integration on another, was tested at a site in Boulder, Colorado. In this study,
energy shifting provided flexibility in design, allowing for a larger array and a
lowered initial cost through the displacement of roofing materials. It was
concluded that there are some advantages to energy shifting. Most importantly,
energy shifting offers architects a larger palette in which to communicate the most
valuable facet of BIPV design: synergy.
It is through the working of a sound methodology that BIPV synergy
surfaces. Starting with realistic building loads, trimmed by energy efficiency
strategies and control measures, the time of day when demand occurs is predicted.
Even with user-friendly software such as Energy 10(1.4), an accurate prediction is
time-consuming. This critical step leads to an understanding of the hourly load
profile and building envelope characteristics where synergy with PV elements can
be developed. The reward for such inquiry is a more accurate load in which to
match PV supply. At this point, the impact of a PV sunshade can truly be
identified. In like manner, the savings in material in roof integration can be
accurately measured. If the process is short-circuited, opportunities can be
overlooked.
The arduous method described is out of sync with the simple question,
what is the payback? It is intentionally so. The real advantage of PV is not the
savings on the electric bill. As previously described, it is the added benefits that
emerge when PV becomes an integral part of the building envelope that is most
valuable. Until as a profession, architects describe these benefits and support them
with sound data, BIPV will not penetrate price sensitive markets.
A broad concept that is applicable in a wide range of contexts, energy
shifting can be added to the list of strategies that assist designers. Moreover, if
37


utilized on a large scale, there are even greater benefits. Using energy shifting to
connect multiple buildings would change the flow of energy. Lessening the steady
stream of electricity from a central plant, energy shifting would become the
channel for distributed generation. In doing so, local policy and current utility rate
conditions would be challenged. By utilizing this strategy, architects would be
proactively shaping the future, setting in motion the transition to a post-fossil fuel
economy.
38


APPENDIX A
BACKGROUND INFORMATION
We have a habit of writing... to make the work as finished as possible,
to cover up all the tracks, and not worry about blind alleys or
describe how you have the wrong idea first, and so on.
So there isn t any place to publish, in a dignified manner,
what you actually did in order to get to do the work.
Richard Philips Feyman, 1918-1988
The Changing Energy Industry
Until a few years ago, the most promising application of PV was large,
Megawatt-sized grid feeding plants installed by electric companies (Lysen &
Yordi, 2001). Seeing the potential for improving the aesthetics of buildings and
replacing traditional building materials with photovoltaics, architects began
integrating PVs into projects. Now BIPV represents the fastest growing
application for PV in OECD countries (Lysen & Yordi, 2001).
The growing interest in PV of architects, developers, governments,
utilities and environmental groups has brought about a marked change (Lysen &
Yordi, 2001). The avoidance of occupying large amounts of land and integration
of PV into the economy of the building are positive changes. Other advantages
include the savings on transmission, distribution, investment, and savings through
displaced facade material costs (McNelis, 2001). It is now generally accepted that
decentralized production of electricity on the electric grid, through BIPV, is a
more viable option than Megawatt-sized central PV power stations (McNelis,
2001).
Conventionally, energy companies generate electricity in a large
centralized plant, be it coal, nuclear, hydro or gas, and transmit it through a high-
voltage system to substations. Since the purpose of the high-voltage lines is to
interconnect sources, it has the appearance of a grid. From the substations, local,
low-voltage lines distribute the electricity to the end user. Low-voltage
distribution lines are supplied by the transmission grid and have little built-in
generation, hence they are rarely connected and are normally radial networks
(Markvart, 2000). Fifty years ago, an increase in demand meant adding another
power plant, but in todays economy, bigger is better does not make economic
39


sense. These plants are very capital intensive and create large environmental
impacts. Energy companies are looking for cost-effective solutions that do not
relinquish too much control.
In the United States and Canada, deregulation is challenging the monopoly
that energy companies have over power generation and so is PURPA1. Embedded,
or distributed generation (smaller generators, like PV, connecting to the local
line), is becoming more common. This is posing problems because of the radial
nature of the low-voltage lines (Markvart, 2000), but there is an undeniable trend
towards distributed generation (Smeloff & Asmus, 1997,155).
Sacramento Municipal Utilities District (SMUD), A Case Study
SMUD, recognizing that PV has benefits not matched by conventional power,
took a bold step (Table 1.1.). After two decades of nuclear energy problems,
SMUD was eager to diversify its portfolio, and repair its badly tarnished image
without large rate increases. Its PV Pioneer I Rooftop Program charges customers
15% above usual rates in order to install a PV system on their roof (Smeloff &
Asmus, 1997). The panels are utility owned and excess energy feeds into the local
line (Osbom, 2001). This project, along with a few other installations, has
expanded to provide 10 MW of power, enough to meet the needs of more than
3,300 homes (Energy Services Bulletin: Western Area Power Administration,
January 2002).
SMUDs success was cost-cutting while promoting environmental
progress (Smeloff & Asmus, 1997). In order to make this work, SMUD combined
California residents environmental concern with a new economic look at
distributed generation. SMUDs unique economic outlook contains the following
principles:
1. When comparing PV cost to conventional methods, include not only the cost
of power from the central station, but also the cost of transmission and
distribution.
2. Account for costs of PVs over a commercialization life cycle rather than over
a project life cycle.
3. Work for sustained and orderly development. A large one-time purchase will
increase prices for new technologies given the forces of supply and demand.
To support manufacturers who need sustained markets, incrementally add to
the program over time. (Smeloff & Asmus, 1997)
1 Sections 201 and 210 of the Public Utilities Regulatory Act of 1978 (PURPA) broke the utility
monopoly on electricity production by requiring utilities to buy power from independent power
producers (Berman & OConnor, 1996).
40


Table 1.1. PV Benefits for Utilities.
PV benefits not matched by conventional power:
Modularity: wide variety of sizes, make small investments without large capital
Short lead time: capital is not tied up for long period of time, quick construction
Lower operating costs: PV systems have few moving parts
Suitability: for distributed siting
Minimal environmental impact: PV installations do not produce emissions
(Smeloff & Asmus, 1997)__________________________________________________
SMUDs successful strategy is revolutionary, but few other companies are
following suit. The reason is that solar (kW) is one millionth the amount of power
generated by a nuclear plant (Dunn, 2001) and overall, total electric consumption
continues to grow about 3% a year (Huber & Mills, 1999). It is like turning an
ocean liner with a string tied to its bow. For many companies, renewable energy is
too small scale to consider unless mandated. Several new state policies have done
just that legislating a Renewable Portfolio Standard, but it will take time to
implement. In the meantime, SMUD is looking for places to put PV and is
pointing the way in how to make PV economical in North America.
41


a) Inclined roof
e) inclined PVs
with windows
i) atftiim
t>5 fool with
integrated Hies

f)icitned wall
with windows
j) vertical
v_\
c) saw-toothed
north light tool
s
S
g) fixed sunshades k) vertical with
windows
di curved roef/wslf
Photovoltaics & Architecture
Rendali Thomas
N 2t
h) moveable sunshades
Demonstration of Ways of Integrating PV into the Building Form: Reformatted
from original work by Randall Thomas in Photovoltaics & Architecture
42


APPENDIX B
DATA COLLECTION
BP Library
Monthly Electric Demand (kW)*
A) Actual Monthly Electric Demand for BP Library in 2001/02 (kW).
Total Annual Electric Use: 860,200 kWh
B) Occupant Use for BP Library
Open Year-Round: M-Th 9 am-9 pm, F/Sa 9 am- 6 pm, Su 12 pm-5 pm
C) HVAC Schedule
M-Th 5 am-system on, 7 am-exhaust fans on, 8:30 am HVAC on, 8:30 pm HVAC off
F/Sa same as M-Th except 6 pm HVAC off, Su 11 am HVAC on, 6 pm HVAC off
D) Conditions
Site: 9Ih and Arapahoe, Boulder, CO, USA
Cost: a high priority, but open to convincing arguments that go beyond the bottom line.
Building Orientation: remains the same, all self-shading building elements to be considered.
Footprint: 53.000 ft" (4924 m2) addition, old library not to be included in study.
Layout: daylighting to be included in Energy 10 simulation, program areas to remain the same.
Form: general form of building to remain the same and considered as platform for integration.
Building Load: general load to be based on current occupancy, lighting and HVAC schedules.
Other factors: Architects: Midyette/Seieroe & Associates, Energy Consultants: AEC, Client City
Intent: need to create a building that is visually and psychologically open to the public.
Daylighting proved to be more cost effective and active solar energy was not included.
43


WS Center
Monthly Electric Demand (kW)*
based on utility bill, averaged
over 24 month period in 2000-02
A) Actual Monthly Electric Demand for WS Center in 2001/02 (kW).
Total Annual Electric Use: 296,720 kWh
B) Occupant Use for WS Center.
Open Year-Round: M-F 7 am-4 pm (Lunch from 11:30 am-12:30 pm)
Sa/Su Closed
Annual Shutdowns of facility occur for one week in July and one week in
December.
C) Meter Reading July 2002
July 25/02 11 am-0.396, 11:32 am-0.417, 11:53 am-0.424, 12:33 pm-0.446
Maximum peak kW for day occurred at 1:20 pm 0.475 x 160(multiplier) = 76
kW.
July 26/02 10:39 am-0.475, 11:40 am-0.489
Maximum peak kW for day occurred at 11:40 am 0.489 x 160(multiplier) = 78
kW.
44


APPENDIX C
BP LIBRARY ENERGY 10 SIMULATION
BP Library 2 / AutoBuild Shoebox
ANNUAL ENERGY USE
Energy 10 Simulation of Total Energy Use in kBtu/ft2.
BP Library 2 / AutoBuild Shoebox
Energy 10 Simulation of Total Electric Use in kWh/ft2.
45


BP Library 2 Nov 02, 2002
Energy-10 Summary Page Weather file: denver.etl
Variant: AutoBuild Shoebox Comments: Saved as F:\PROJBPL2, Var. 5
Description: Reference Case Low Energy Case
Floor Area, ft2 53585.0 53585.0
Surface Area, ft2 93679.3 93679.3
Volume, ft3 1607550.0 1607550.0
Surface Area Ratio 1.14 1.14
Total Conduction UA, Btu/h-F 5076.9 4857.8
Average U-value, Btu/hr-ft2-F 0.054 0.052
Wall Construction 8in brick/foam, R=20.0 8in brick/foam, R=20.0
Roof Construction flat r-38, R=38.0 flat r-38, R=38.0
Floor type, insulation Slab on Grade, Reff=44.5 Slab on Grade, Reff=200.5
Window Construction 4060 double, low e, U=0.29 4060 dble, low e, U=0.29,etc
Window Shading None 40 deg latitude
Wall total gross area, ft2 40094 40094
Roof total gross area, ft2 26793 26793
Ground total gross area, ft2 26793 26793
Window total gross area, ft2 7224 8412
Windows (N/E/S/W:Roof) 87/73/85/56:0 65/28/225/20:25
Glazing name double low-e, U=0.26 double low-e, U=0.26
Operating parameters for zone 1
HVAC system DX Cooling with Gas Furnace DX Cooling w/ Gas Furnace
Rated Output (Ht/SCool/TCool),kBtuh 1671/1146/1528 1152/840/1120
Rated Air Flow/MOOA,cfm 70752/8038 50841/8038
Heating thermostat 68.0 F, no setback 68.0 F, setback to 63.0 F
Cooling thermostat 78.0 F, no setup 78.0 F, setup to 83.0 F
Heat/cool performance eff=80,EER=30.0 eff=80,EER=30.0
Economizer?/type no/NA yes/electronic type A
Duct leaks/conduction losses, total % 11/10 11/10
Peak Gains; IL,EL,HW,OT; W/ft2 1.08/0.05/0.36/3.03 0.61/0.04/0.36/2.30
Added mass? none 26793 ft2, 8 in emu
Daylighting? no yes, continuous dimming
Infiltration, in2 ELA=5332.5 ELA=1443.4
Results: (Energy cost: 0.270 $/Therm, 0.054 $/kWh, 5.430 $/kW)
Simulation dates 01-Jan to 31-Dec 01-Jan to 31-Dec
Simulation status, Thermal/DL valid/NA valid/valid
Energy use, kBtu 4554573 2071808
Energy cost, $ 63550 35923
Saved by daylighting, kWh NA 20597
Total Electric, kWh 752618 422114
Intemal/External lights, kWh 245782/10953 60339/8762
Heating/Cooling/Fan, kWh 0/40363/77882 0/20454/45902
Hot water/Other, kWh 0/377639 0/286657
Peak Electric, kW 290.5 193.3
Fuel, hw/heat/total, kBtu 256824/1729590/1986414 256824/374604/631429
Emissions, C02/S02/N0x, lbs 1246114/6164/3344 641893/3404/1813
Energy 10 Summary for BP Library Simulation
46


Energy-10 Building Integrated Photovoltaics Summary Page:
Nov 18, 2002
Project Path: F:\PROJBPL2
Variant: 6
Project Title: BP Library 2, AutoBuild Shoebox
System Description:
Total PV Array Area, ft2 / m2
Total PV Rated Output, kW
Total Inverter Rated Capacity, kW
Array 1
BIPV Type / Rated Power, kW
No. of Modules
Area/Azimuth/Tilt
Window-U/Tvis/SHGC, (units)
PV Simulation Results:
PV System Output, kWh
PV Sellback, kWh
PV Output before Power Conditioning Losses
Array 1, kWh
Total Bldg Electric Load, kWh
Supplied by PV, kWh
Supplied by Grid, kWh
Peak PV Net Output, kW, time
Peak PV Output to Bldg, kW, time
Peak PV Sellback to Grid, kW, time
Bldg Peak Elec., kW, time
Bldg Peak PV Coincident Output, kW
Bldg Net Elec. Peak, kW, time
PV Ann. Capacity Factor
Low Energy Case
465 / 43
1.6
2.0
Window-Integrated / 1.6
60
465/175/35
tbd
2660
0
2988
422131
2659
419472
1.7 3/6 12:00
3.0 6/3 11:00
0.0 12/31 23:00
190.0 8/29 14:00
1.0
189.0 8/29 14:00
0.18
Energy 10 PV Simulation A for Strategy (A).
47


Energy-10 Building Integrated Photovoltaics Summary Page:
Nov 18, 2002
Project Path: F:\PROJBPL2
Variant: 5
Project Title: BP Library 2, AutoBuild Shoebox
System Description: Low Energy Case
Total PV Array Area, ft2 / m2 535/50
Total PV Rated Output, kW 6.0
Total Inverter Rated Capacity, kW 6.0
Array 1
BIPV Type / Rated Power, kW Wall-Integrated / 6.0
No. of Modules 60
Area/Azimuth/Tilt 535/168/40
U-Value, (units) tbd
PV Simulation Results:
PV System Output, kWh 9701
PV Sellback, kWh 71
PV Output before Power Conditioning Losses Array 1, kWh 10905
Total Bldg Electric Load, kWh 422131
Supplied by PV, kWh 9630
Supplied by Grid, kWh 412501
Peak PV Net Output, kW, time 5.3 4/15 11:00
Peak PV Output to Bldg, kW, time 6.0 12/16 11:00
Peak PV Sellback to Grid, kW, time 1.9 4/5 7:00
Bldg Peak Elec., kW, time 190.0 8/29 14:00
Bldg Peak PV Coincident Output, kW 3.1
Bldg Net Elec. Peak, kW, time 187.0 8/29 14:00
PV Ann. Capacity Factor 0.21
Energy 10 Simulation B for Strategy (B).
48


Energy-10 Building Integrated Photovoltaics Summary Page: Nov 18, 2002
System Description:
Total PV Array Area, ft2 / m2
Total PV Rated Output, kW
Total Inverter Rated Capacity, kW
Array 1
BIPV Type / Rated Power, kW
No. of Modules
Area/Azimuth/Tilt
U-Value, (units)
PV Simulation Results:
PV System Output, kWh
PV Sellback, kWh
PV Output before Power Conditioning Losses
Array 1, kWh
Low Energy Case
1305 /121
14.3
16.0
Roof-Integrated /14.3
50
1305/180/20
tbd
23887
491
25762
Peak PV Net Output, kW, time
Energy 10 PV Simulation C for Strategy (C).
13.8 3/6 12:00
Energy 10 Input Assumptions and Rationale
1. EER =30 was used to simulate the load of an evaporative cooler as
discussed at Energy 10 Training Workshop at CRES conference June,
2002.
2. Average daily peak electric was based on highest occupancy hour and
HVAC schedules. A more accurate profile could have been found by
monitoring the actual load through meter reading; however this would
have required expensive testing equipment and was beyond the scope of
this study.
49


APPENDIX D
WS CENTER ENERGY 10 SIMULATION
WS Center Reference Case
The WS Center (17300 ft2/ 1580m2) is located immediately west of the
library. Typical of its size and building type, the center exhibits high summer
cooling loads. However, seasonal variation is muted by the consistent high
electric demand for kitchen appliances. Actual total annual electric load is
296,720 kWh (see Appendix A). Simulated annual electric load (293, 260 kWh)
roughly matches the reference case.
WS Center 4 / AutoBuild Shoebox
Simulated Annual Energy Use for WS Center in kBtu/ft2.
Simulated Annual Electric Use for WS Center in kWh/ft2
50



WS Center 4 Nov 01, 2002
Energy-10 Summary Page Weather file: denver.etl
Variant: AutoBuild Shoebox Comments: Saved as F:\PROJ4, Var. 3
Description: Reference Case Low Energy Case
Floor Area, ft2 17300.0 17300.0
Surface Area, ft2 39969.7 39969.7
Volume, ft3 173000.0 173000.0
Surface Area Ratio 2.15 2.15
Total Conduction UA, Btu/h-F 2834.3 1371.6
Average U-value, Btu/hr-ft2-F 0.071 0.034
Wall Construction steelstud 4, R=15.0 steelstud 6 poly, R=19.2
Roof Construction attic, r-30, R=35.Q attic, r-30, R=35.0
Floor type, insulation Slab on Grade, Reff=35.8 Slab on Grade, Reff=161.1
Window Construction 4060 double, alum, U=0.70 4060 low-e al/b, U=0.31
Window Shading 40 deg latitude 40 deg latitude
Wall total gross area, ft2 5370 5370
Roof total gross area, ft2 17300 17300
Ground total gross area, ft2 17300 17300
Window total gross area, ft2 2304 1800
Windows (N/E/S/W:Roof) 20/24/21/23:8 9/4/31/3:28
Glazing name double, U=0.49 double low-e, U=0.26
Operating parameters for zone 1
HVAC system DX Cooling with Gas Furnace DX Cooling with Gas Furnace
Rated Output (Heat/SCool/TCool),kBtuh 524/292/389 266/247/329
Rated Air FIow/MOOA,cfm 18264/2595 15865/2595
Heating thermostat 68.0 F, no setback 68.0 F, setback to 63.0 F
Cooling thermostat 78.0 F, no setup 78.0 F, setup to 83.0 F
Heat/cool performance eff=80,EER=8.9 eff=90,EER=13.0
Economizer?/type no/NA yes/fixed dry bulb, 60.0 F
Duct leaks/conduction losses, total % 11/10 3/0
Peak Gains; IL,EL,HW,OT; W/ft2 1.08/0.05/0.36/3.69 0.81/0.04/0.36/3.19
Added mass? none 8650 ft2, 8in emu
Daylighting? no yes, continuous dimming
Infiltration, in2 ELA=714.2 ELA=193.3
Results: (Energy cost: 0.400 $/Therm, 0.058 $/kWh, 5.430 $/kW)
Simulation dates 01-Jan to 31-Dec 01-Jan to 31-Dec
Simulation status, Thermal/DL valid/NA valid/valid
Energy use, kBtu 1365128 782658
Energy cost, $ 26337 17636
Saved by daylighting, kWh NA 15174
Total Electric, kWh 293260 200476
Intemal/Extemal lights, kWh 57375/3536 27862/2829
Heating/Cooling/Fan, kWh 0/50027/29388 0/23442/14132
Hot water/Other, kWh NC NC
Peak Electric, kW 134.2 92.9
Fuel, hw/heat/total, kBtu NC/NC/364436 NC/NC/98573
Emissions, C02/S02/NOx, lbs 281081/1595/835 437181/2357/1250
Summary of Energy 10 Simulation for WS Center.
51


Energy Efficient Recommended Strategies
1. Energy Efficient Kitchen Appliances The WS Center currently has very
high plug loads for the kitchen. Since the program dictates the electrical
use, it is not practical to eliminate this demand; however it can be lessened
by the use of more efficient appliances.
2. HVAC system and controls An upgrade of the HVAC system and
computerized control system would aid in lessening this load.
3. Glazing During a 1990 addition/renovation, double-pane glazing with
aluminum frames were specified, but not all windows throughout the
building were replaced. A small savings would be gained if this were
addressed.
Low Energy Case
By reducing electric demand through design changes to the reference case,
a low energy case is established. The total electric load (200,476 kWh), a 32%
reduction from the reference case, will be used in calculations hereafter.
Simulation of Hourly Load
Based on building use, it is estimated that the average daily peak load is
between 10 am and 11 am. This coincides with a high kitchen demand for energy
during lunch preparation (see Figure 3.4. for profile and Appendix C for expected
seasonal variation).
52


Average hourly profile for WS Center in kW.
Energy-10 Building Integrated Photovoltaics Summary Page: Nov 18, 2002
System Description:
Total PV Array Area, ft2 / m2
Total PV Rated Output, kW
Total Inverter Rated Capacity, kW
Array 1
BIPV Type / Rated Power, kW
No. of Modules
Area/Azimuth/Tilt
U-Value, (units)
Array 2
BIPV Type / Rated Power, kW
No. of Modules
Area/Azimuth/Tilt
U-Value, (units)
PV Simulation Results:
PV System Output, kWh
PV Output before Power Conditioning
Array 1, kWh
Array 2, kWh
Total, kWh
Total Bldg Electric Load, kWh
PV Ann. Capacity Factor
Low Energy Case
2872/267
31.4
32.0
Roof-Integrated / 14.3
50
1305/ 180/20
tbd
Roof-Integrated / 17.1
60
1567/135 /20
-tbd-
527191
Losses
25925
30526
56451
200477
0.21
Energy 10 Simulation 1 Array for the WS Center and 1 for the BP Library
53


APPENDIX E
STRATEGY COMPARISON
Economic
Simple Payback Method
Strategy A i Strategy B , Strategy C
Size of System (watts) 1,600 6,000 14,300
System Life (yrs)1 25 25 . 25
Cost per watt2 $7.00 $7.00 $7.00
Cost of Installation $11,200.00 $42,000 $100,100
Roof Material Displacement3 $13,000
Adjusted Cost of Installation $87,100
Annual Energy Output (kWh/yr)4 2,660 9,701 23,887
Cost per kWh5 $0.13 $0.13 $0.13
Annual Energy Savings $345.80 $1,261.13 $3,105.31
Annual Maintenance6 -100 -100 -100
Thermal Savings7 $20.00
Annual Value of System $265.80 $1,161.13 $3,005.31
Payback in Years 42 36 30
Incentive Needed to Breakeven ($4,555.00) ($12,971.75) ($11,967.25)
Assumptions:
1 Life of panels industry standard
2 Cost/W AC installed SMUD pays $5-$6 US Dollars AC installed W (Correspondence, SMUD
Tour, June 2002)
SEI estimates $10 install cost x W x # of panels = cost of system. (PV Workshop, May 2001)
$7 is assumed, not only because it is between the two extremes, but because it is an agreed current
standard in the field and the figure the City of Boulder would use if assessing the project.
3 Roof Material Displacement The cost of the new roof shingles that are displaced by the panels
is estimated at $13,000 as per article: fiberglass composition shingles 32,00 sf roof ave cost
$13,000 (Sunset, April 2001)
4 Annual Energy Output (after Power Conditioning Losses a calculated in Energy 10 Simulation
for each array taking into account latitude, azimuth, tilt and weather variables.
5 Cost of Electricity Electricity is currently 7 cents/kWh (Xcel Energy 2002). Assuming cost of
electricity doubles in 25 years (life of the system), 13 cents/kWh is the average cost of electricity.
6 Annual Maintenance The PV array needs very little maintenance, checking for new plant
growth, dust accumulation, junction boxes and wiring (SEI PV Workshop, May 2001).
7 Thermal Savings This is an estimation of decreased cooling loads due to shading from semi-
transparent panels. Further analysis for more than a ball park figure
54


Net Present Value Calculation for Strategy C
Size of System (watts)
System Life (yrs)
Cost per watt
Cost of Installation
14,300
25
$ 7.00
$ 100,100
Annual Maintenance Cost Annual Energy Output 3%/yr $ - $ (65) $ (67) $ (69) $ (71) $ (73) $ (75) $ (78) $ (80) $ (82) $ (85) $ (87)
(Kwh/yr) 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996
Cost per Kwh 5%/yr $ 0.073 $ 0.077 $ 0.080 $ 0.085 $ 0.089 $ 0.093 $ 0.098 $ 0.103 $ 0.108 $ 0.113 $ 0.119 $ 0.125
Annual Energy Savings $ 1,825 $ 1,916 $ 2,012 $ 2,112 $ 2,218 $ 2,329 $ 2,445 $ 2,568 $ 2,696 $ 2,831 $ 2,972 $ 3,121
0 1 2 3 4 5 6 7 8 9 10 11
Year 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Cash Flow $ (87,100) $ 1,851 $ 1,945 $ 2,043 $ 2,147 $ 2,256 $ 2,370 $ 2,490 $ 2,616 $ 2,748 $ 2,887 $ 3,034
$ (90) $ (93) $ (95) $ (98) $ (101) $ (104) $ (107) $ (111) $ (114) $ (117) $ (121) $ (125) $ (128) $ (132)
24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996 24,996
$ 0.131 $ 0.138 $ 0.145 $ 0.152 $ 0.159 $ 0.167 $ 0.176 $ 0.184 $ 0.194 $ 0.203 $ 0.214 $ 0.224 $ 0.235 $ 0.247
$ 3,277 $ 3,441 $ 3,613 $ 3,793 $ 3,983 $ 4,182 $ 4,391 $ 4,611 $ 4,841 $ 5,084 $ 5,338 $ 5,605 $ 5,885 $ 6,179
12 13 14 15 16 17 18 19 20 21 22 23 24 25
2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
$ 3,187 $ 3,348 $ 3,517 $ 3,695 $ 3,882 $ 4,078 $ 4,284 $ 4,500 $ 4,728 $ 4,966 $ 5,217 $ 5,480 $ 5,757 $ 6,047
NPV Calculation
5.5%/y ($13,347.74)
Strategy A NPV Calculation ($1,719.15), Strategy B NPV Calculation ($6,442)
55


Environmental
Environmental Impact measured by the amount of Carbon Dioxide that would be
displaced if the strategy was implemented.
C02 Pollution Coefficient 1.344/kWh of electricity (Energy 10 manual, U.S. National
Average)
Strategy A: 2988 kWh x 1.344 = 4016 lbs of C02/yr.
Strategy B: 10,905 kWh x 1.344 = 11,713 lbs of C02/yr.
Strategy C: 25,765 kWh x 1.344 = 34,524 lbs of C02/yr.
56


GLOSSARY
The majority of the terms below are derived from the literature. Those
undocumented were coined by the investigator for the purposes of interpretation
within the context of the present study.
Amorphous Silicon A thin film PV silicon cell having no crystalline structure. (SEI
Manual)
Architectural/Market benefits Incentives for energy shifting projects. Architectural
benefits include ease of integration, pleasing to the eye, good composition, etc. Market
benefits include economic, environmental and educational rewards for including PV.
Array A mechanically integrated configuration of modules together with support
structure. (SEI Manual)
Azimuth Angle between true south and the point directly below the location of the
sun. Measured in degrees (e.g. true south is 180). (SEI Manual)
BIPV Integration of photovoltaic cells into one or more of the exterior surfaces of the
building envelope.
Crystalline Silicon A type of PV cell made from a crystal or polycrystalline slice of
silicon. (SEI Manual)
Deregulation In the United States and Canada, deregulation is challenging the
monopoly that energy companies have over power generation.
Energy shifting when the design process focuses on linking building use and load
analysis, expanding beyond one building envelope.
Distributed Generation (or Embedded) Smaller generators connected at lower voltages
than the transmission voltage. (Markvart)
Efficiency The ratio of output power to input power. Expressed in a percentage.
Grid The network of transmission lines, distribution lines, and transformers used in
central power systems. (SEI Manual)
Grid-tied An electrical system that is connected to utility distribution lines as opposed
to off-grid where there is no connection to the utility.
57


Kilowatt (kW) One thousand watts of electricity. Ten 100-watt lights use 1 kW of
electrical power.
Kilowatt hour (kWh) One kW of electrical power used for one hour. The most
common measurement of electrical consumption, most grid connected electrical meters
measure kWh for billing purposes.
Load Any device that consumes electricity in order to operate. Also, the amount of
electrical power being consumed at any given moment.
Life-Cycle Cost An estimate of the cost of owning and operating a system for the
period of its useful life, usually expressed in terms of present value. (SEI Manual)
Net Metering Utility company compensation for excess energy produced and exported
to the grid.
Passive Solar Design An approach to heating and cooling homes through simple
devices and architectural design, as opposed to mechanically operated heating and
cooling systems. (Perlin & Butti)
Peak Load The maximum load or electrical power consumption occurring in a given
period of time. (SEI Manual)
Polycrystalline Silicon Silicon that has solidified rapidly enough to produce many
small crystals which are arbitrarily arranged in more than one layer.
PURPA Sections 201 & 210 of the U.S. Public Utilities Regulatory Policies Act of
1978 (PURPA), broke the utility monopoly of electricity production by requiring
utilities to buy power from independent power producers (Berman & OConnor, \996\
PV System An installed aggregate of solar array, power conditioning and other
subsystems providing power to a given application. Called an active system.
Renewable Portfolio Standard (RPS) A separate issue from deregulation, RPS is
designed to create incentives for clean supply-side resource additions to be included in
a utility companys portfolio. For instance, an approved RPS bill would mandate that
10% of a utility companys portfolio come from renewable sources by 2010.
Tilt Angle Angle of inclination of the collector measured in degrees from the
horizontal. Optimal angle of collection is dependent on the location on earth.
58


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Ones work may be finished someday, but ones education never.
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60