Citation
BEPS and its effect on energy consumption, Denver area homes

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Title:
BEPS and its effect on energy consumption, Denver area homes
Creator:
Thirkell, Angela, 1890-1961
Publication Date:
Language:
English
Physical Description:
133 leaves : illustrations, maps, plans ; 28 cm

Subjects

Subjects / Keywords:
Dwellings -- Energy consumption -- Colorado -- Denver Metropolitan Area ( lcsh )
Energy consumption -- Colorado -- Denver Metropolitan Area ( lcsh )
Dwellings -- Energy consumption ( fast )
Energy consumption ( fast )
Colorado -- Denver Metropolitan Area ( fast )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 132-133).
General Note:
Submitted in partial fulfillment of the requirements for a Master's degree in Urban and Regional Planning (presently Planning and Community Development), College of Design and Planning.
Statement of Responsibility:
by Leslie Parker.

Record Information

Source Institution:
University of Colorado Denver
Holding Location:
Auraria Library
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
09003663 ( OCLC )
ocm09003663
Classification:
LD1190.A78 1981 .P38 ( lcc )

Full Text
UNIVERSITY OF COLORADO
BEPS AND ITS EFFECT ON ENERGY CONSUMPTION DENVER AREA HOMES
A STUDIO III THESIS PROJECT SUBMITTED TO THE FACULTY OF THE URBAN AND REGIONAL PLANNING COMMUNITY DEVELOPMENT PROGRAM COLLEGE OF ENVIRONMENTAL DESIGN
IN CANDIDACY FOR THE
DEGREE OF MASTERS IN URBAN AND REGIONAL PLANNING
By
Leslie Parker Denver, Colorado
March 1981


TABLE OF CONTENTS
Page
CHAPTER I INTRODUCTION
Background.............................. 1
Purpose................................. 3
Research Methods........................ 4
Scope................................... 6
Limits of Research...................... 6
Organization............................ 7
Conclusion.............................. 8
CHAPTER II METHODOLOGIES AND ASSUMPTIONS OF THE AUDITS
Beps, Background........................ 9
Brief Description.................... 11
Research............................. 13
Methodology.......................... 16
Steps for the Evaluation of a Single Family Residential Dwelling Unit
(Beps)............................. 19
Implementation....................... 20
Manual Method
Brief Description.................... 21
Limitations of the Methodology..... 22
Steps For Determining The Design Energy Consumptions............................ 24
Parameters, Assumptions................. 25
Choice of Neighborhood............... 26
Building Assumptions................. 27
CHAPTER III COMPARISON OF BEPS TO DENVER AREA HOMES
The Audit............................... 34
Single Family Detached............ 36
Single Family Attached.............50
Comments
Roof Ceiling......................... 66
External Walls....................... 66
Glass (Transmission)................. 67
Glass (Solar)........................ 68
Floors............................... 69
Infiltration......................... 70
Internal Loads....................... 71
Annual Thermal Load..................... 73
Single Family Detached............ 75
Single Family Attached............ 77
Water................................ 81


CHAPTER IV
POTENTIAL ENERGY SAVINGS
83
Insulation............................ 86
Triple Glazing........................ 87
Infiltration.......................... 88
Site Orientation...................... 89
Landscaping........................... 91
Design................................ 93
Density............................... 94
Flat Plate Collectors................. 95
Alternative Measures As A Means to
Achieve Beps Energy Levels.......... 96
Site Orientation...................... 99
Solar Access....................... 99
Solar Skyspace..................100
Shadow Patterns.................100
Shadow Projections..............101
Solar Design Strategies............101
Building, Lot and Street
Orientation...................102
Setback Requirements............103
Zero Lot Lines..................104
Height Restrictions.............104
Townhomes.......................104
Landscaping........................105
Solar Access....................105
Tradeoffs..........................106
Shadow Projections in Chimney Hillsll2 CHAPTER V CONCLUDING REMARKS
Conclusions...........................113
Limits of the Research................115
Needs for Further Research............115
Recommendations.......................116
APPENDIX..................................................118
FOOTNOTES.................................................131
BIBLIOGRAPHY
132


LIST OF TABLES
Page
I. Climatic Data............................. 25
II. Operating Conditions...................... 26
III. Major Physical Characteristics and
Assumptions............................... 29
IV. Space Heating and Cooling Demand
SF Detached............................... 64
V. Space Heating and Cooling Demand
SF Attached............................... 65
VI. Design Energy Budgets SF Detached...... 79
VII. Design Energy Budgets SF Attached....... 79
VIII. Comparison of Design Energy Budgets to
DOE's Design Energy Budgets............... 80
IX. Total Potential Energy Savings............ 84
X. Comparisons of Potential Reductions
Space Heating/Cooling & Water Heating..... 85
XI. Comparisons of Potential Reductions
Space Heating & Cooling................... 85
XII. Potential Hourly Savings From More
Insulation (SF Detached).................. 86
XIII. Potential Annual Energy Savings From
More Insulation........................... 86
XIV. Potential Hourly Energy Savings From More
Insulation (SF Attached).................. 87
XV. Potential Energy Savings From Triple
Glazing................................... 88
XVI. Potential Energy Savings From Improved
Building Tightness........................ 88
XVII. Solar Heat Gain From South Exposure
(SF Detached)............................. 90
XVIII. Solar Heat Gain From South Exposure
(SF Attached)............................. 90
XIX. Potential Energy Savings Using Landscaping
as Windbreaks (SF Detached)............... 92
1


93
94
95
118
119
123
124
125
126
127
128
129
130
Potential Energy Savings Using Landscaping as Windbreaks (SF Attached)................
Potential Energy Savings From Design Efficiency.................................
Potential Energy Savings From Sharing Common Walls...............................
Surface Resistances........................
Thermal Resistances of Building and Insulation Materials.........................
Cooling Load Temperature Difference For Roofs......................................
Adjustment Factors for Various Window and Sliding Door Types.....................
Shading Coefficients for Single Glass With Indoor Shading........................
Cooling Load Temperature Difference for Walls......................................
Cooling Load Factors for Glass.............
Cloud Cover Factor.........................
Maximum Solar Heat Gain Factors............
Air Changes Due To Infiltration............
2


LIST OF ILLUSTRATIONS
Page
1. Picture of Detached Unit - Smokey Hills....... 30
2. Picture of Attached Unit - Chimney Hills...... 31
3. Site Plan of Detached Unit - Smokey Hills.... 32
4. Site Plan of Attached Unit - Chimney Hills.... 33
5. South Wall Access Limited by 35 & 28 Foot
Buildings to South.............................108
6. Subdivision, Davis, California................ 108
7. Using Flag Lots for Proper Orientation on
North/South streets...........................109
8. South Building Orientation Subdivision,
Davis, California.............................109
9. Reducing Frontage..............................110
10. Uniform Versus Staggered Setbacks..............110
11. North Zero Lot Line Siting.....................Ill
1


CHAPTER I INTRODUCTION
Background
It is estimated that over one-third of the total energy consumed in the United States is used for heating, cooling, lighting, and hot water heating in buildings. It is also estimated that approximately 40% of this demand is wasted through inadequate energy conservation measures in the design and equipment of these buildings. Due to the national effort to reduce total energy demand and relieve United States dependence on foreign oil there has been a recognized need to improve building standards as they relate to energy conservation. Some local and state governments as well as private industry are initiating action on their own to reduce the energy needed to operate buildings. But while some improvement in designs has occured since the Arab oil embargo of 1973, most buildings still lack the necessary energy conservation features required to reduce energy waste as much as is possible. Many localities are still not requiring adequate building codes and there is inconsistency among standards which do exist. Many authorities feel that more consistent standards need to be not only encouraged but required of local governments so that more energy efficient buildings and the use of renewable technologies will be promoted throughout the country.
One federal program which would require more stringent building standards is currently before Congress. These standards, Building Energy Performance Standards (Beps) are proposed by the Department of Energy and if passed will
1


apply to all new residential and commercial buildings.
Beps will set energy consumption goals (in Btus) for residential and commercial buildings according to climate and type of building. State and local governments will be expected to implement the program or they will risk the loss of any federal assistance for the construction and mortgaging of buildings. These energy levels, called Design Energy Budgets, (DEB) are expected to improve existing building standards and thus reduce demand for space heating and cooling as well as the heating of hot water. These standards will not specify the materials or methods of design but are performance standards and will evaluate the total energy consumption of the building as a whole.
That is, as long as the building does not go over the allowable Btu limit, the program is not concerned with the specific building materials or design used to achieve the desired energy demand.
The energy levels set by Beps have been derived by using prototype designs of single family homes to establish the energy requirements of these homes if they met the existing minimum energy building performance standards of the draft proposed HUD minimum Property Standards for One and Two Family Buildings and NAHBs Thermal Performance Guidelines. DOE then developed designs to maximize the reduction of energy in buildings through the use of energy conservation and passive solar technologies such as increased insulation of walls to R-19, ceilings to R-38, triple glazing of windows, improved window area and orientation.
2


Such building characteristics were added to the minimum energy standards to establish this energy demand. Beps separated residential buildings into two categories only attached and detached and established different Btu limits for each. Other variables such as environmental considerations, life cycle cost analysis, type of fuel used were considered and helped to determine the final demand figure. This final level, the Design Energy Budget, cannot be exceeded by the annual consumption of the new building.
Purpose
The purpose of this study is to evaluate these proposed Building Energy Performance Standards and to establish how typical single family residential homes of two newly constructed neighborhoods in the Denver area compare to the energy levels set by the standards.
Assuming that Beps will reduce current energy consumption, as is its intent, analyses will be made on how certain energy conservation measures, especially site planning issues, could improve current building practices and enable the homes to meet the federal standards.
In doing this study, the main objectives are:
1) To establish if Beps will reduce energy demand in the residential secter of Denver.
2) To become knowledgeable about Beps. This program may affect local and state governments in the future, if passed, and a good understanding of the program would benefit any planner or government. Even if not passed,
3


Beps should at the very least provide ideas on how to reduce energy in homes.
3) To learn how to perform an audit and to establish which factors are most important in energy consumption of a building. With limited knowledge of audits I wanted to develop a good understanding of the most important elements. This will be accomplished by walking through a seven step process which estimates the hourly thermal loads of heating and cooling systems.
4) To establish how and to what extent site planning principles can save energy in homes. This will be done by quantifying energy savings from various site planning measures.
Research Methods
Doe is developing a computer program to be used by municipalities to determine if a new building meets their desired energy performance goals. This program is currently being amended and is not available, so a manual audit of a comparable nature was sought for use in this study. A rather sophisticated model is required in order to be able to evaluate the effect of specific differences in design.
The audit used here was developed by Mathematical Sciences Northwest, Inc. for another DOE project. It analyzes several major building thermal componentsroof/ceiling, external walls, external glass (transmission), external
glass (solar), floor, infiltration, internal load and ventilation. The hourly thermal loads are then converted
4


to annual thermal loads. The basis of this audit is
based primarily on the 1977 Ashrae Handbook of Fundamentals, which is also heavily used in the Beps methodology. Thus, this audit allows for the establishment of energy demand based on many of the same variables, including site design, suggested by Beps.
This audit will be used to establish energy levels equivalent to the Beps Design Energy Budgets. It will incorporate the same building characteristics and site design measures which were used in Beps to develop their energy goals. These same audits will then be used to determine the energy consumed in the same types of homes in the Denver area, using the building characteristics and designs as these buildings were actually built. This will provide the opportunity to compare Beps and Denver homes to determine if any reduction in consumption will occur if Beps is passed by Congress. After these comparisons are made, the same process will be used to establish how much energy can be saved by individual building and site planning measures.
The neighborhoods to be used for this comparison are a conventional single family home from a neighborhood in Arapahoe County and a townhome in the city of Aurora.
Both of these neighborhoods are recently built. Construction of the conventional single family neighborhood began in 1977 and continues today and the townhomes were built in 1980. According to planning officials and building code officers in both Aurora and Arapahoe County the homes in
5


both of these communities are typical of homes as they are now being built in the area. The homes in the neighborhoods have different site orientation characteristics, and thus many site design measures can be compared in the audits.
The specific information used in the study is based on information provided in the Beps regulations and Environmental Impact Statements and from the developers of the Denver homes. Other information from the audits has been obtained from the planning offices and buildings departments of the City of Aurora and Arapahoe County.
Further information on Beps was obtained from the Department of Energy and from the consultant on Beps, Lawrence Berkely Laboratories.
Scope
The scope of this study will include any building envelope measures which are specified by Beps as recommendationswall insulation of R-19, ceiling insulation of R-38, and triple glazing of windows. Some site planning principles will also be analyzedwall and glass orientation to the south, and the use of landscaping as windbreaks and as shading devices.
This analysis reviews only residential units and addresses space heating, space cooling, and water heating only.
Limits of Research
This research is limited to only those items
6


mentioned above. Other building measures, such as different levels of insulation than those specified, are not addressed in this analysis.
Due to the scope and time limit of this study, certain issues were not addressedsuch as the feasibility of Beps and of implementing some of these measures, cost-effectiveness of measures, peoples attitudes, etc. While these issues will affect the liklihood of implementation of any of the measures discussed in this study, they will not be discussed in depth at this time.
The study also does not include energy analysis of transportation and infrastructure factors which would affect total energy consumption.
Also not covered is any evaluation of how the audit used in this study compares to the DOE-2 computer program. While recognizing similarities and possible differences, it is not the intent of this study to draw any conclusions regarding the manual audits' use.
Organization
The following chapter will describe Beps in more detail and explain its history, the research involved, and the proceedures and steps required. It will also describe the manual audit to be used in the study and then identify assumptions and common factors of each or both methods. Chapter 3 will provide the audits comparing the Beps models to the Denver area models with explanations of differences which might exist. The fourth chapter will evaluate
7


individual energy conservation measures and estimate potential savings from each. This will include the establishment combinations of alternative measures to meet or surpass Beps energy goals. The final chapter will address any final remarks, limits of the research, and further studies identified as necessary, recommendations resulting from this study.
Conclusion
The final results of this study demonstrate that Denver area homes are substantially more energy consumptive than the Beps models would be. In order for these homes to pass the Beps requirements, it would appear that energy demand would need to be reduced from 20 to 25 percent. Equally as important, it also appears that there are several measures that can be taken, especially site planning principles, which would reduce energy consumption an additional 15-17%.
8


CHAPTER II METHODOLOGIES AND ASSUMPTIONS OF THE AUDITS
This chapter describes the federally proposed legislation (Beps), the manual audit used in this study to determine space and water heating, and discusses the assumptions and parameters pertaining to these methods. The background and purpose of Beps, its criteria, procedures, and implementation requirements are all addressed. A brief description of the manual audit, which is substituted for the Beps computer program, is provided along with its general comparisons to Beps. The final section provides common assumptions as well as the differences between Beps and the local models.
BEPS BACKGROUND
In August of 1976 Congress passed the Energy Conservation Standards for New Buildings Act of 1976 which mandated the development, promulgation, implementation, and administration of energy performance standards. As a direct result of this order Building Energy Performance Standards (BEPS) was created. The purpose of Beps is to promote increased energy efficiencies in new residential and commercial buildings as well as increase the use of renewable energy sources. Again, Beps addresses only space heating and cooling, and the heating of hot water.
While most states (37 by the fall of 1978) have adopted and are implementing energy conservation standards for at least some types of new buildings, these standards
9


are considered minimal in effect. Most of these statewide regulations are based on the Ashrae 90-75 "Energy Conservation in New Building Design" which was the state-of-the-art for building standards in the mid 1970's. These standards classify buildings simply as residential and commercial and included specific building requirements such as insulation levels and high level performance in water, electrical, and heating systems, etc.
Beps was originally under the jurisdiction of the Department of Housing and Urban Development but was later transferred to the Department of Energy who has proposed draft regulations concerning the development and promulgations of energy performance standards. These draft regulations were published in November of 1979 and were subject to public review. These regulations have now been delayed for at least a year while modifications are made. Their status under the 1981 administration is unknown.
Beps was created to greatly improve upon previous standards. Twenty different building classifications were developed for more precise energy analysis and seven different climate regions were used to address the wide variety of weather conditions. The largest difference to other existing standards, however, is that the method of achieving the required energy level or goal is left to the designer. Specific structural requirements are not required, but specific energy levels, or performance standards, expressed in Btus/sq ft, are set and must not be exceeded. This allows
10


the builder to develop his own method and design as long as it meets the requirement.
More innovation in building design is encouraged and since it allows a builder to use a new process for reducing energy over conventional practices the regulations allow more flexibility in design.
The specific goals for residential alone are to reduce costs for the home owner, save energy for the country, and to achieve greater conservation than present practices. According to DOE projections BEPS is expected to reduce the energy used by Single Family residential units by 22-51% from energy required for current practices and standards. ^
And since the standards do not regulate the operating, maintenance and conservation practices after the structure is built, there is potential for even further energy savings.
Costs are also expected to be reduced both for operating or fuel costs and through the use of some inexpensive energy conservation measures such as site orientation, window locations etc. Even the costs of more expensive energy conservation items will be offset by lower fuel bills. More on the costs of the measures will be explained in further detail later in this chapter. The fact that energy is saved and costs reduced reflects improvement with energy conservation practices throughout the country.
BRIEF DESCRIPTION
DOE has developed three energy levels within BEPS
11


which determine how the standards are used:
1. Energy Budget Level (EBL) base energy level set for different classifications of buildings.
2. Design Energy Budget (DEB) level set for a specific design. This figure is the sum of the EBL's for space heating and cooling plus the EBL for water heating.
3. Design Energy Consumption (DEC) the estimated annual rate of consumption of a building design. This figure cannot exceed the Design Energy Budget.
In order to determine the Design Energy Consumption levels DOE has developed the Standard Evaluation Techniques, which in the case of residential buildings is a computer program, DOE-2; other programs exist for community buildings. Local and state governments are expected to purchase the program, or locate a suitable substitution.
As a builder proposes a dwelling unit, the structural design and orientation characteristics are fed into the program which will then determine the structure's Design Energy Consumption level. If this level is above the Design Energy Budget, which is already determined by DOE, the building will not be approved by the appropriate government. Energy budgets are not limits, but they do represent the amount of energy the building would be expected to consume if it was operated under standard conditions. The building when in use may well expend more energy than the Design Energy Budget.
12


For developments with more than one style of home, the typical or average home is used for the entire development, unless there is a wide variety in building characteristics .
Also, the Design Energy Budget and Design Energy Consumption may not produce totally accurate Btu limits.
But because identical assumptions are used in determining each level, accuracy is not essential. What is important is how a particular building compares in relation to its equivalent prototype.
RESEARCH
The development of BEPS and the energy levels occurred over three phases from 1977 to 1978 during which data were collected and energy goals were established.
Phases 1 and 2 established the data base for current practices and the third phase added energy, environmental and economic analysis to establish final energy goals.
Phase 1 consisted of surveys of new buildings built before 1976 so that effects of the 1973 oil embargo would be demonstrated in designs. For residential units this entailed an analysis of 120,000 homes, built in 1975 and 76, which had been surveyed by the National Association of Home Builders Research Foundation. Here estimates were made of the energy use according to various building characteristics .
Then DOE developed 4 prototype single family residential designssingle story, split level, 2-story
13


detached and 2-story townhouses. Ten cities throughout the nation, representing different climates, were used in the study. Twenty teams of building and energy experts redesigned the four types of homes for energy conservation and using available technology tried to minimize energy usage. A computer program was used to establish results.
Phase 2 provided a more detailed analysis of the redesign of the prototypes. Specific energy levels were determined for three levels1) as designed for 1975-76 homes, 2) as modified to conform to existing guidelines, namely the draft Proposed HUD minimum Property Standards for One and Two Family Dwellings, which specifyes transmission requirements, and the National Association of Home Builders Thermal Performance Guidelines which include a cost/benefit analysis, and 3) more detailed analysis to achieve practical levels. This stage also began to incorporate more climate, economic and environmental input as well.
During Phase 3 further refinement was added.
1) National economic impact of BEPS under various alternatives was considered, 2) Environmental impacts were studiednamely indoor air quality, 3) Various regulatory methods were reviewed, 4) Weighting factors for different fuel types were established, 5) Life cycle cost analyses were added.
After identifying present energy conservation
14


measuresfcost factors were evaluated more extensively to determine the practability of energy requirements. Combinations of different designs were used in the 10 localities and analysis made of the energy and cost savings. This included a life cycle cost analysis of the fuel types and of the investment of the specific energy conservation measures.
Four energy levels were evaluated:
1) the minimum level on life cycle cost effectiveness, meaning only those energy conservation measures which make the largest impact on energy savings are used. These measures also have to be in current use. The measures used here were determined to be:
a) increased levels in insulation
b) increased glazing on windows
c) improved tightness of buildings
2) 10% reduction in energy over #1
3) 20% reduction in energy over #1
4) 25-30% increase in energy above #1 The criteria for evaluation were:
1) energy savings to the nation
2) economic impacts on individuals and the nation
3) practicability of designing buildings to meet the levels indicated
4) first-cost impacts
5) environmental impacts and
6) extent that use of renewables are encouraged
Alternatives 2 and 3 were eliminated because they
15


were felt to be impractical and unachievable due to limitations in orientation, access to the sun, lack of knowledge about technologies etc. Two and 3 were also expected to result in high first costs. Number four was ruled out because it simply did not reduce energy use enough, and had less favorable economic and environmental impacts, and failed to encourage the use of renewable technologies. Therefore, alternative #1 was chosen as the most favorable and practical in satisfying the above criteria and the specific measures listed were incorporated into the energy goals.
The energy levels set by alternative #1 will be monitored and updated regularly by DOE. Analysis will be made to evaluate energy reduction, cost reduction and to identify technological and administrative problems.
Changes will be made in energy levels as technologies improve and problems are identified.
METHODOLOGY
While DOE strongly urges use of the Standard Evaluation Technique, they will be allowing substitution of other methodologies. These can be either other computer models or manual methods but substitutions must be approved by DOE before their use is acceptable. In fact,
DOE would like to see a manual method developed so that less time and money be spent on residential and small commercial units. It is essential that the alternative
16


method be equivalent and constant to DOE's method. DOE will eventually list methods which can be used in place of their model.
The Standard Evaluation Technique consists of three parts:
1) A calculation method to determine an estimate of the energy level of a building design
2) Fixed parameters
Weather, Standard Building Operation Conditions fixed data. This information is all pre-determined within the program
3) Instructions for use of the technique.
The method and its use will not be discussed here. However, it is important to further address the fixed parameters as they are based on many assumptions which will be duplicated later on in the audits of Denver homes. This information is predetermined for constancy and cannot be altered. The weather information is based on data from NOAA and for Denver includes heating degree days, cooling degree days, average monthly temperatures, etc. The fixed data refers to specifics such as daylight savings time, number of holidays, etc.
But most importantly, DOE developed certain operation standards which are used for all buildings within a building classification. These too cannot be altered by the design for determination of the energy level. This ensures that all conditions are the same for everyone and that only building characteristics alter the energy levels
17


which are established. These operation standards for Single Family Residences include the following:
Hours of operations Indoor temperature Number of occupants Lighting
Hot water demand Equipment
A very important factor which needed to be added to the Design Energy Budget was the value of the type of fuel being used. Due to flucuations in the prices of fuels and the national policy toward various fuels it was necessary to somehow alter the standards to encourage the use of the more preferable fuels in design. A value is determined by DOE for each fuel type. This value is based on 1) the replacement costs of the fuel to the country, and 2) a premium of $1.29/million Btus was added to oil and gas on the premise that saving oil and gas is worth more to the nation than cost figures alone reflect. The values applied to each fuel will be continually updated to reflect current costs and national policy.
The weighting factor is applied after the total
energy requirements by fuel types are established for the
2
building. The Btu/ft /yr for each type is then multiplied by the appropriate weighting factor. The sum of all fuel types equals the Design Energy Consumption. If Beps were in force now, the weighting factors would be as follows:
18


1
3
Weighting Factors Natural Gas Oil 1.22
Electricity 2.79
Hopefully this would discourage electric heating/cooling.
STEPS FOR THE EVALUATION OF A SINGLE FAMILY RESIDENTIAL DWELLING UNIT (BEPS)
1) Produce a description of the building design
2) Determine gross area of the home
3) Select building classification either attached or detached
4) Select applicable climate provided by SMSA
boundaries
5) Determine the Design Energy Budget. Establish the Energy Budget Levels for both space conditioning and hot water. Add these figures together for the Design Energy Budget.
6) Determine the Design Energy Consumption
a) Establish the energy required by fuel
type
b) Multiply each fuel requirement by the weighting factor (determined by DOE)
c) Add the results for the total Design Energy
Consumption
7) Compare Design Criteria Levels
If the Design Energy Consumption is below the Design Energy Budget the building can be approved.
19


If the Design Energy Consumption exceeds the Design Energy Budget then modifications on the design must be made until it does meet the Design Energy Budget.
IMPLEMENTATION
As stated, state and local governments are expected to enforce BEPS. These jurisdictions will obtain or have access to the Standard Evaluation Technique and will determine if the building design in question meets the BEPS goal. If local or state governments do not implement BEPS, they will be risking the loss of all federal financial assistance to any part of the state. This includes not only direct or indirect federal financial aid in the form of loans, subsidies, guarantees etc, but also loans from banks and savings and loans which are regulated by the Federal Reserve System and other national boards and corporations.
Exceptions to this can occur. If very little construction is occurring in an area or if the costs of the program are found to be too high for a locality, that area may be excluded from the regulations. Also, if the local or state governments involved have adopted and are implementing a building code which meets the standard goals they may be excluded from BEPS as well. DOE will be identifying building codes which will be equivalent to BEPS. State and local governments will then be able to model their codes after these model codes in order to pass acceptable statutes. DOE may also publish a method by which states could evaluate codes to determine if their code would be equivalent to the Standards.
20


MANUAL METHOD
Brief Description
As stated earlier, the DOE Computer methodology was not readily available for use. Therefore a substitute method was found in order to evaluate the energy demand of Beps and local homes. The method to be used here was extracted from "Estimating Energy Impacts of Residential and Commercial Building Development" which includes a step-by-step audit for space heating and cooling. This audit was developed by Mathematical Sciences Northwest Inc. for DOE, however not specifically for use in Beps.
This audit looks at the heat loss and gain through ceilings, walls, floors and glass. By determining building materials, window size and glazing, orientation of the homes, and many other particulars, equations were provided for a series of categories, which could then be calculated. These calculations combine to provide hourly energy demand for heating and cooling for the entire unit. This figure can then be converted to an annual energy demand amount.
The steps taken in this process parallel those of Beps discussed earlier. The major differences are that I had to gather the data and I had to use a manual audit to determine energy levels. The collection of data entailed not only going to the developer for specific information, but also trying to determine all the standard parameters used by Beps in their methodology. Once this was accomplished the energy requirements were established. These steps are
21


outlined below.
LIMITATIONS OF THE METHODOLOGY
This methodology looks at many of the same factors as does Beps--infiltration effects, solar heat gain through windows and walls, building materials, internal loads, efficiencies of furnaces, etc. The basis for analysis on this information is based on ASHRAE 1977 Handbook of Fundamentals for both methods.
There were, however, some differences. These will be described in more detail in the next chapter, but they should be mentioned here as well. It is not known to what extent these differences would affect overall findings.
Infiltration Rates There were descrepencies between recommended rates of Beps and the audit used here, so compromises based on best judgement were made.
Floor Heat Loss There was also confusion over recommended R-levels of floors in the Denver region and assumptions made on this calculation could well affect the overall results. The assumptions made were on the conservative side so results would reflect a larger Energy Budget Level. Ventilation The assumption is made that whenever possible people will choose to cool their homes through the natural ventilation of windows rather than operate their air-conditioners. When ventilation is provided through ducts above the ceiling and is in an unheated attic, as is in the case in these four models, the manual audit does not address the issue. It is
22


not known if DOE's model would include calculations.
Solar Heat Gain Through Walls in Winter These calculations are not included in the audit. Most experts felt the effect too minimal for the amount of effort needed to determine the heat gain by a manual method.
Solar Heat Gain Through Glass in Winter As this calculation was not included in the audit, it was added in order to determine its effect.
23


STEPS FOR DETERMINING THE DESIGN ENERGY CONSUMPTIONS
1) . Secure information regarding dimensions, building materials, building practices, glass area, and orientation from the builder.
2) . Determine fixed parameters used in the Beps method:
Climatic factors
Standard building operation conditions
3) . Calculate equations for each item (walls, glass, infiltration, etc.) using the above data. This provides an hourly energy requirement for space heating and cooling expressed in btus for both the Beps equivalent and the local homes.
4) . Establish the annual energy requirements by square footage for the space heating Energy Budget Level.
5) . Multiply the annual demand by the appropriate weighting factor as done in the Beps methodology.
6) . Divide the domestic hot water factor (given) by the gross area of the building for the water Energy Budget Level.
7) . Sum of the two Energy Budget Levels for the Design Energy Consumption.
24


PARAMETERS, ASSUMPTIONS
Many assumptions were made by Beps regarding climatic and operating conditions to ensure accuracy and consistency. These factors, listed below, were incorporated into the manual audit to provide consistency here as well. The climatic data is shown in Table I.
The inside air temperatures, heating and cooling degree days, night setback hours, and sunshine percentage are all based on standard perimeters used in Beps. The outside air temperature is based on information from the National Weather Service.
The operating conditions appear in Table II.
25


4 TABLE II OPERATING CONDITIONS
Hours of operation 16 hours with night setback 11 p.m. 7 a.m.
Indoor Temperature
heating (Oct May) o o r
cooling (June Sept) 0 00 r-~
Equipment Efficiency .7%
Hot Water Demand 29,500, OOOBtu/yr/d.u.
Lighting (internal load) .3435Btu/ft^
Ventilation (by natural means)
CHOICE OF NEIGHBORHOOD
In order to test Beps against current Denver area building practices I found two newly constructed neighborhoods--one a detached single family housing development and the other a townhome community. These are both still in the process of being built and represent energy conservation practices which have been added since the 1973 oil embargo.
Single Family Detached
I have used the subdivision of Smokey Hills located in unincorporated Arapahoe County southeast of Cherry Creek Dam, approximately 25 miles from downtown Denver. Several developers are building in the same subdivision but the particular homes used in this study are built by Wood Brothers. There are 240 homes consisting of many stylesranch, split-level, and 2-story. The building structure information has been directly provided by Wood Brothers and refers to all their homes. Dimension figures used here however refer to
26


their 2-story model. This should not greatly affect Design Energy Budgets according to DOE who grouped the three models mentioned into the same energy level. Average figures from the 2-story house in Smokey Hills do coincide with average figures in the area and in the Beps models.
Single Family Attached
Chimney Hills, a townhome community in Aurora, was used to compare attached housing. This development is located at 1-225 and Iliff about 15 miles from downtown Denver and consists of 120 one and two bedroom units. It is being built by Environmental Development, Inc. who also provided the information on the structure. The dimensions used here apply to two bedroom units and are very close in size to the townhouse model used by Beps to develop their standards.
According to the building departments in both Arapahoe County and the city of Aurora the homes in these neighborhoods are typical of homes being built at this time. The building material reflects current building standards in insulation levels, glass requirements, etc, and little more. Thus in using these homes against Beps it is reasonable to conclude that most new homes will result in approximately the same energy consumption. Of course, all homes will vary to some degree due to site location, construction practices and knowhow, etc.
BUILDING ASSUMPTIONS
Once the neighborhoods were determined and the data collected comparisons were made between Beps and local
27


characteristics. These are shown in Table III. This lists the specific assumptions of Beps models and the building characteristics as found on the local models of detached and attached homes.
Figures 1 and 2 provide pictures of both the detached and attached units used as models for the Denver area. These help show the design and building characteristics of the units.
Figures 3 and 4 show the site plans of both developments. As can be seen there is little attention to south orientation in either community. The townhomes do have several units facing south, but only those further south will receive solar radiations year round. The northern row of homes will be blocked from south exposure in winter months. Figure 6 in Chapter 4 demonstrates a more ideal site plan for comparison.
In summary this chapter describes the proposed Beps methodology and the substitute methodology used in this study. It also provides some of the framework of the basic parameters and assumptions, and differences between the models of homes being studied here.
28


TABLE III MAJOR PHYSICAL CHARACTERISTICS AND ASSUMPTIONS
Beps Denver-area SF Detached SF Attached
Walls R-19 R-ll R-ll
Ceiling R-38 R-30 R-21
Tightness Average to tight Minimum Minimum
Glazing Triple-all walls Double 2 walls Double 2 walls
Orientation E/W All directions All directions
Landscaping None Minimum, if any Minimum if any
Area Det. 1600 Att. 1360 ft2 1530 ft2 1404 ft2
29




31


U)
ro




CHAPTER III COMPARISON OF BEPS TO DENVER AREA HOMES
This chapter includes the audits of both the conventional single family detached dwellings and the townhome units. These audits reflect the energy consumption of homes based on the Beps goals and those of the buildings as they are being constructed in the Denver area. The final results of these audits are presented for comparisons as well as comments which explain any differences which may exist.
The Audit
The audits consist of specific equations for determining seven categoriesheat loss through walls, ceiling, floors, glass, and infiltration; and heat gain through glass and internal load.
An equation is provided for each category and the variables of each equation are completed either by inform-mation from Beps, the developers of the buildings, or is given. That information which is given appears in Tables 22 through 31 in the Appendix. These tables are based on Ashrae information and are provided for use in the audit by Mathematical Sciences Northwest, Inc. A list of building information used in the audit preceedes each model, and the operating conditions appear in Table 2 in Chapter II. Each category in the audit is presented with the equation, the measures used or assumed for that equation, and final hourly btu figure. These categories are totalled in
34


Tables 4 and 5 along with brief explanations of why differences may exist between Beps and local dwelling units. More detailed explanations follow the audits.
MAJOR SYMBOLS
U Overall Heat Transfer Coefficient (But/hr/ft^/F)
R Resistance Value
Rt = Total Resistance Value
A Area of Appropriate Space (roof, wall, floor, glass, etc.)
AT Temperature difference between outside and inside location. Toa Tin
Toa = Outside Air Temperature
Tin = Inside Air Temperature
35


3 S.S'
SINGLE FAMILY DETACHED
Smokey Hills (Arapahoe County) Dimensions-2 story unit
Beps
Dimensions-2 story unit

3o
Square footage 1530 Roof
V plywood sheathing Asphalt Shingles med.
color
Ceiling
V Plasterboard Insulation R-30 2x4 Trusses
Area 765 ft2 Floors
3/4" wood subfloor carpet with rubber pad h" plasterboard
crawl space
Area 765 ft2
Walls
h" plasterboard Insulation R-ll 3/4" plywood 60% wood siding med color
40% brick, face
Square footage 1600 Roof
V plywood sheathing Asphalt Shingles med. color Ceiling
y Plasterboard Insulation R-38 2x6 Trusses
Area 800 ft2 Floors
3/4" subfloor carpet with rubber pad 1" insulation around parameter
2 x 10 crawl space
Area 800 ft2 Walls
y plasterboard Insulation R-19 y composition sheathing Aluminum siding med color
Area walls glass
e/w 450 fy n/s 421 ft2
- excluding
glass, 45 ft, 45 ft
Area walls glass
e/w 498 ft^ n/s 383 ft2
- excluding
glass 30 ft, 30 ft
36


Smokey Hills Glass
Area 90 ft2 2 walls only
Double glazed .25 air space clear
Building volume 12,623
Heating system Natural Gas, forced air
Cooling system Electric
Hot water heating Natural Gas
Beps
Glass
Area 120 ft2 4 walls
Triple glazed .5 air space clear
Building volume 13,200
Heating system Natural Gas, forced air
Cooling system Electric
Hot water heating Natural Gas
37


ROOF/CEILING
Heating (October May)
Q /u \ = U x A x 4 T v(Btu/hr)
U = overall heat transfer coefficient A = area of ceiling
CLTDcor = cooling load temperature difference (corrected)
Smokey Hills Beps
Element Resistance Resistance
(R-value) (R-value)
Outside Surface
Resistance (Table 2 3) .17 .17
Materials (Table 2 4)
V plywood .62 V plastergoard .45 Insulation R-30 30.00 Inside Surface .62 V plywood h" plasterboard Insulation R-38 .62 .45 38.00 .62
Total Rfc 31.86 39.86
U= 2 u 31.86=.031Btu/hr/ft /F u= I 39.86=.25Btu/hr/ft 2 /F
A= 765 ft2 800 ft2
AT= -29 -29
Q= .031x765x(-29)=-688Btu/hr .025x800x(-29)=-580Btu/hr
38


Cooling (June Sept)
Q (Btu/hr)
Element
U x A x CLTDcor
Smokey Hill
Resistance
(R-value)
Beps
Resistance
(R-value)
Outside Surface .25
Materials
V plywood .62
V plasterboard .45
Insulation R-30 30.00
Inside Surface .76
Total R 31.08
1 2
U=Il o8=*032BtU//hr/ft /F
A=Area of Ceiling 765 ft2
.25
V plywood .62
y plasterboard .45
Insulation R-38 38.00
.76
40.08
1 2 ^0>08=.025Btu/hr/fy /F
800 ft2
CLTDcor=Cooling Load Temperature Difference (corrected) CLTD Lightweight roof with night setback (Table 24) -46F
L=Latitude correction = 0 To-Outside temperature correction To=Toa-85
80 85 = -5
Ti=indoor temperature correction Ti=78 Tin 78 78 = 0
R=roof color correction (given) R=1.0 for dark colored roofs .5 for light colored roofs
CLTDcor = CLTD + L + To + Ti x R
= -46 +0-5+0x.5= 20F
2
U = .032Btu/hr/ft /F A = 765 ft2
CLTDcor 20
Q = .032(765)(20)=+514Btu/hr
2
.025Btu/hr/ft /F
800 ft2 20
.025(800) (20)=+400Btu/hr
39


EXTERNAL WALLS
Heating (October May)
Q,n, ,, . = U x A x T
(Btu/hr)
1
U=
Rt
Element
Smokey Hills Resistance
Beps
Resistance
(R -value) (R-value)
Outside Surface .17 .17
Materials
h" plasterboard .45 V plasterboard .45
Insulation R-ll 11.00 Insulation R-19 19 .00
3/4" plywood .94 3/4" plywood .94
60% wood siding .81 Aluminum siding .61
40% brick, face .44 h" composition
sheathing 1 .32
Inside Surface .68 .68
Total Rt 14.49 23 .17
u= 14.49 = 07Btu/hr/ft 2/f u=I u 23.17 = .04Btu/hr/ft 2 /F
A=area of external walls excluding glass
East/West 450 ft^ 498 ft:
North/South walls 421 ft2 383 ft
AT=-29 F i to VO o *1
Qe/w= .07 (450) (-29) = -914 Qe/w= .04(498)(-29) = -578
Qn/s= -07(421) (-29) = -855 Qn/s= .04(383)(-29) = -444
2(855) = -3538Btu/hr 2(585) + 2(444) = -2044Btu/h
40


Cooling (June Sept)
(Btu/hr)
u=i
= u X A X CLTDcor (Wall 1)
+ u X A X CLTDcor (Wall 2)
+ u X A X CLTDcor (Wall 3)
+ u X A X CLTDcor (Wall 4)
Element
Smokey Hills Resistance
Beps
Resistance
(R -value) (R-value)
Outside Surface .25 .25
Materials
V plasterboard .45 V plasterboard .45
Insulation R-ll 11.00 Insulation R-19 19.00
3/4" plywood .94 3/4" plywood .94
60% wood siding .81 Aluminum siding .61
40% brick, face .44 h" composition sheathing 1.32
Inside Surface .68 .68
Total Rt = 14.57 23a25
U=y4 57= .07But/hr/ft^ o /F 1 = .04Btu/hr/ft2 /F U 23.25
A=area of external walls exclud ing glass 0
East/West 450 ft 498 ft.
North/South walls 421 ftZ 383 ft
CLTDcor corrected cooling load temperature difference
= CLTD (table ) = Latitude corrected+To + Ti x Wall color
L = latitude correction -_0 To- outdoor temperature correction Toa 85 80 85 = -5
Ti- indoor temperature correction 78 Tin 78 78 = 0
W= wall color (given)
1.0 for dark colored walls .5 for light colored walls .83 for medium colored walls
41


area area
Wall CLTD L To Ti W CLTDcor Smokey Beps
N 12 + 0 - 5 + 0 X .83 5.8 421 383
E 22 + 0 - 5 + 0 X .83 14.1 450 498
S 17 + 0 - 5 + 0 X .83 10 421 383
W 22 + 0 - 5 + 0 X .83 14.1 450 498
Smokey Hills U = .07
A = see above chart CLTDcor see above chart Q = N 421(5.8) = 2442
E 450(14.1)= 6345 (. 07) 19,343 = 1,354Btu/hr
S 421(10) = 4210 -----------
W 450(14.1)= 6346 19343
Beps U = .04
A = see above chart CLTDcor see above chart Q = N 383(5.8) = 2221
E 498(14.1)= 7022 (.04)20,095=804Btu/hr
S 383(10) = 3830
W 498(14.1)= 7022 20095
42


GLASS(TRANSMISSION)
Heating (October
Q . ,, , = U x A
(Btu/hr)
U = Overall heat
- May) x /)T transfer
coefficient
A = External glass area
/}T = Difference between indoor and outdoor temperature
U
Smokey Hills Tables 25-26 Glass double glazed .5 air space metal sash
.59 for windows
Beps
Tables 25-26 Glass triple
glazed .5 air space metal sash/metal frame door .37 for windows
A = 90 ft2
A = 120 ft2
2
windows 84 ft? door 33 ft
A T = 29
Q = .59(90) (-29) = -1540 Btu/hr Q = .37 (-29) (84) = 901
.34 (-29) (36) = 355
-1256 Btu/hr
Cooling (June Sept)
^ (Btu/hr)
U x A x CLTDcor
CLTDcor = CLTD + To + Ti
CLTD = 6(given) no night setback To = Toa-8 5
80-85=-5 Ti = 78-Tin 78-78=0
CLTDcor = 6-5+0=l
U = .67 for windows A = 90 ft2
.47 for windows .43 for door
120 ft2 2
windows 84 ft door 36 ft
Q = .67 (90) (1) = 60 Btu/hr Q = .47(84) (1) = 39
.43 (36) (1) = 1_5
54 Btu/hr
43


GLASS(SOLAR)
Heating (October May)
Q/t,. , . = A x MSHG x CCF x Exp
(Btu/yr)
A area of glass
MSHG Maximum Solar Heat Gain
CCF Cloud Cover Factor
Exp Percentage of Glass area exposed to sunlight
Smokey Hill Beps
A 90 ft2 120 ft2
MSHG South 49 Btu/ft2/hr North 84 Btu/ft /hr~ East/west 29 Btu/ft /hr
MSHG South 49 Btu/ft2/hr North 84 Btu/ft /hr2 East/west 29 Btu/ft /hr
CCF l(see table 30) CCF l(see table 30)
Exp. .8 Exp. .8
Smokey Hill
Glass MSHG - Total -
area Exp Btu/ft /hr CCF Btu/ft /hr
E 45 .8 29 1 1044
W 45 .8 29 1 1044 2088 Btu/hr
Beps
N 30 .8 8 1 192
E 30 .8 29 1 696
S 30 .8 49 1 1176
W 30 .8 29 1 696
2766 Btu/hr
44


Cooling (June Sept)
Q(Btu/hr)= A x Sc x MSHG x CLF x CCF A = Area of glass
SC = Shading coefficient
MSHG = Maximum solar heat gain (Btu/ft/hr)
CLF = Cooling load factor CCF = Cloud cover factor
Smokev Hill Beps
A 90 ft2(2 walls) 120 ft^(4 walls)
SC .52 (given) . 45(given)
MSHG See Table 31 See Table 31
CLF See Table 29 See Table 29
CCF .9(given) .9 (given)
Smokey - Hill
Wall A SC MSHG CLF CCF Q(Btu/hr)
E 45 .52 213 .23 1 1032
W 45 .52 213 .23 1 1032
2064 Btu/hr
Beps
Wall A SC MSHG CLF CCF Q(Btu/hr)
N 30 .45 38 .48 1 222
E 30 .45 213 .23 1 595
S 30 .45 138 .27 1 453
w 30 .45 213 .23 1 595
1865 Btu/hr
45


FLOOR
Heating (October May)
Q,n, /u=UxAx£T w (Btu/hr)
U = Overall heat transfer coefficient A = Area of floor
/}T = Difference between indoor and out door temperature
u4t
Smokey Hills Beps
Element Resistance Resistance
(R-value) (R-value)
Outside Suracce .17 .17
Materials
V plasterboard .45 wood subfloor .94 wood subfloor .94
carpet and rubber 1.23 carpet and 1.23
pad rubber pad 3/4" plywood .93
Inside Surface .61 .61
Total R = 3.40 3.88
1 ~o 1 _o
U-3.40 = .29Btu/hr/ft /F 3.88 = .26Btu/hr/ft /F
A = 765 ft2 800 ft2
AT = -29 -29
0 = .29(765)(-29)=-6,434 Btu/h r .26 (800) (- 29)=-6,032 Btu/hr
Cooling
If the floor is directly on the ground or over an unheated or unventilated basement, this need not be calculated. These units are built both with and without basements and since the energy level would be the same for each unit under Beps,
I have not used a basement model.
46


INFILTRATION
Heating (October May)
3
A,*,. /1 .= .018 x Ac x Ft x ZaT
(Btu/hr)
Sensible heat gain Ac air changes*
AT Difference between indoor and outdoor temperatures
Smokey Hills Beps
Ac Air changes 1.2 AC = 1.0
Ft3 12,523 13,200
AT - -29 F -29 F
Q = .018 x 1.2 x 12623 x (-29) Q = .018 x 1.0 x 13200 x (-29) = 7907Btu/hr = -6890Btu/hr
*Sensible heat gain is the direct addition of heat to the conditional space by any mechanism of conduction, convection and radiation.
47


Cooling (June Sept)
Q ,, = .018 x Ac x Ft3 x AT
*(Btu/hr)
Sensible heat gain
Ac air changes per hour
.AT difference between indoor and outdoor temperature
Smokey Hills Beps
Ac 1.2 Ac 1.0
Ft3 12623 Ft3 15558
AT 2 AT 2
Q = .018 x 1.2 x 545 Btu/hr 12623 x 2 = Q = .018 475 x 1.0 x 15558 x 2 Btu/hr
. 2 3
Latent heat gain ^Btu/hr)= ^*5 x Ac x Ft x W
W = .001 (given)
Smokey Hills Beps
Q = 79.5 x 1.2 x 12623 x .001 Q = 79.5 x 1.0 x 15558 x .001 = 1204 Btu/hr = 1049 Btu/hr
Totals 1749 Btu/hr
1524 Btu/hr
2 Latent heat gain is the moisture (vapor) added to a conditioned
space from people
48


INTERNAL LOADS
Heating and Cooling
This information is set by Beps at a given level which varies
only slightly by the size of ments following this section the structure. Please see com-for further explanations.
Smokey Hills Beps
+2,334 Btu/hr + 2,358 Btu/hr
49


SINGLE FAMILY ATTACHED
Chimney Hills (Aurora) Beps
Dimensions
Dimensions
i) 'Z-'/'jkf

r9
y !

'/e/c/-/
Square footage 1404 Roof
V plywood
Wood shingles med. colored
Vapor-seal, 30 lb felt Ceiling
Insulation R-21
V drywall 2x6 trusses
Square footage 1360 Roof
y plywood
Asphalt shingles med. colored
Ceiling
Insulation R-38 V drywall 2x6 trusses
Area 915 ft
Floor
4" concrete
Carpet with rubber pad 3/4" plywood Vapor barrier
Garage beneath structure
Area 915 ft2
Walls
y plasterboard Insulation R-ll V wood siding medium color
Area Wall excluding glass ,
E 386 ft,
W 165 ft,
S 402 ft
Area 680 ft
Floor
4" concrete
Carpet with rubber pad Vapor barrier 3/4" plywood 1" insulation around parameter
Area 680 ft2 Walls
V plasterboard Insulation R-19 Aluminum siding med.
color
V composition sheathing
Area Wall excluding glass N 297 ft,
S 330 ft,
E 528 ft
50


Chimney Hills Beps
Glass Area 101 ft2 Glass Area 102 ft2
Double glazed .25 air space Clear Triple glazed .5 air space Clear
Building volumn 11,492 Building volumn 10,890
Heating system Natural gas, forced air Heating system Natural gas, forced air
Cooling system Electric Cooling system Electric
Hot water heating Natural gas Hot water heating Natural gas
51


ROOF/CEILING
Heating (October May)
Q(Btu/hr) = U x A x J\ T
U = overall heat transfer coefficient A = area ceiling
T = difference between indoor and outdoor temperature (see climatic data)
U
1
Rt
Element Chimney Hills Resistance (R-value) Beps Resistance (R-value)
Outside Surface .17 .17
Materials
h" drywall .45 V drywall .45
2x6 trusses .62 2 x 6 trusses .62
Insulation R- 21 21.00 Insulation R-38 38.00
Inside Surface .62 .62
Total Rfc 22.86 39.86
__ 1 _o 1 _o
U 22.86 = .044Btu/hr/ft /F 39. 86 = .25Btu/hr/ft2 /F
A= 915 ft2 680 ft2
yJT= -29 -29
Q= .044 (915) (-29) = -1168Btu/hr 025 (680) (-29) = -493 Btu/hr
52


Cooling (June Sept)
Q,_ ,, , U x A x CLTDcor
v (Btu/hr) =
Element Chimney Hills
Resistance
(R-value)
Beps
Resistance
(R-value)
Outside Surface Mater ials-as .25 .25
heating .45 .62 21.00 .45 .62 38.00
Inside surface .76 .76
Total Rt 23.08 40.08
U 23.08 = .043Btu/hr/ft2/F 1 40.08 = .025Btu/hr/ft2/F
A= 915 ft2 680 ft2
CLTD = Cooling Load Temperature Difference corrected
CLTD = Lightweight roof with night setback (table 3)
L Latitude correction 0 To Outside temperature correction To = Toa 85
80 85 = -5
Ti inside temperature correction Ti = 78 Tim
78 78 = 0
R = roof color correction (given)
R = 1.0 for dark colored roofs .5 for light colored roofs
CLTDcor = CLTD + L + To + Ti x R
-46 +0-5+0 x .5 = 20 F
U = .043 BTU/hr/ft2 /F .025 Btu/hr/ft2 /F
A = 915 ft2 680 ft2
CLTDcor 20 20
Q = .043(915) (20) = +787 Btu/hr .025 (680) (20) = +340 Btu/hr
53


EXTERNAL WALLS
Heating (October May)
Q,n. = U x A x A T (Btu/hr)

Element
Chimney Hills Resistance
Beps
Resistance
(R- value) (R -value)
Outside Surface .17 .17
Materials
V plasterboard .45 h" plasterboard .45
Insulation R-ll 11.00 R- 19 19.00
V wood siding .62 is" composition
sheathing 1.32
Inside surface .68 .68
Total Rt 12.92 22.23
__ 1 1 1
U Rt =12.92 = .077 Btu/hr/ft /F 22.23 = . 045 Btu/h:
A=area of external wall areas, excluding glass
North/South walls 551 ft* 525 ft:
East/West walls 402 ft 528 ft
/'T= -29 F
Q = .077 (551) (-29) = -1230 n / s
Qe/W= .077 (402) (-29) = -898
Q(2 walls) = 1230 Btu/hr (3 walls) = 2128 Btu/hr
Qn/s= .045 (525) (-29) = -685
Qe/w= .045(528) (-29) = -690
Q(2 walls) = 685 Btu/hr (3 walls) = 1375 Btu/hr
54


Cooling (June Sept)
(Btu/hr)
u X A X CLTDcor (Wall 1)
+ u X A X CLTDcor (Wall 2)
+ u X A X CLTDcor (Wall 3)
+ u X A X CLTDcor (Wall 4)
u=i
U Rt
Element
Chimney Hills
Resistance
(R-value)
Beps
Resistance
(R-value)
Outside Surface .25
Materials as heating .45
.62
11.00
Inside surface .68
Total Rt+ 13.00
13.00 = .077 Btu/hr/ft2/F
.25
.45
.62
19.32
1.32
.68
22.31
2 22.31 = .045 Btu/hr/ft/F
A=area of external walls, excluding glass area ~
North/South walls 402 ft^ ~ 297/33Q ft
East/West walls 165/386 ft 528 ft
CLTDcor corrected cooling load temperature difference
= CLTD (table) = Latitude corrected + To + Ti x Wall color
L = latitude correction -0 To- outdoor temperature correction Toa 85 80 85 = ^5
Ti- indoor temperature correction 78 Tin 78 78 = 0
W = wall color (given)
1.0 for dark colored walls .5 for light colored walls .83 for medium colored walls
55


External Walls
area area
Wall CLTD L To Ti W CLTDcor Chimney Beps
E 22 + 2 + 0 - 5 + 0 x .83 14.1 E38 6 N297
W 22 + 7 + 0 - 5 + 0 x .83 14.1 W165 S330
Chimney Hills
U = .077
A = see above chart CLTDcor see above chart Q = E 386(14.1) 5443
W 165(14.1) 2327 1077(7770) = 598 Btu/hr (2 walls only)
7770
Beps
U .045
A = see above chart CLTDcor see above chart Q = N 297 (5.8) + 1723
S 330(10) 3300 .045(5023) = +226 Btu/hr (2 walls only)
5023 -----
56


GLASS(TRANSMISSION)
Heating (October May)
(Btu/hr) U x A xaT
U = Overall heat transfer coefficient smaller type
A = External glass area
ZT = Outdoor temperatures difference between indoor
U
Chimney Hills Tables 4 & 5 Glass -double glazed .5 air space metal sash/metal frame door
Beps
Tables 4 & 5 Glass triple glazed .5 air space metal sash/metal frame door
U
A
.59 for windows .4 for windows
.54 for door .34 for door
101 ft2 A = 102 ft2
windows - 670ft2 windows - 69ft2
door 33 ft2 door - 33 ft
AT = 29
Q
.59(68)(-29) = -1163 Q
.54 (33) (-29) = -517
-1680 Btu/hr
= .4(69) (-29) = 800 .34 (33) (-29) = 225
-1125 Btu/hr
Q = U x A x CLTDcor
Chimney Hills Beps
CLTDcor = cooling load temperature difference + To + Ti CLTD 6 (given) no right setback To = Toa 85
80 85 = -5 Ti = 78 78 = 0 6 5 + 0 = 1
Q = .67(67)1 = 6(33)1 =
45
20
65
Btu/hr
Q -
47 (69)1 = 43 (35)1 =
32
14
46
Btu/hr
U = .67 for windows
. 6 for door
.47 for windows .43 for door
A
2
windows 67~ft door 33 ft
2
windows 69-ft door 33 ft
57


6LASS(SOLAR)
Heating (October May)
Q = A x MSHG x CCF x Exp (Btu/hr)
A Area of glass
MSHG Maximum Solar Heat Gain
CCF Cloud Cover Factor
Exp Percentage of glass area exposed to sunlite
Chimney Hills A 100
MSHG South 49 Btu/ft2/hr North 8 Btu/ft /hr ? East/west 29 Btu/ft /hr
CCF l(see table 6)
Exp. .8
Beps A 102
MSHG South 49 Btu/ft2/hr North 8 Btu/ft /hr ~ East/west 29 Bru/ft /hr
CCF l(see table 6)
Exp. .8
Chimney Hills
Glass area Exp MSHG -Btu/ft /hr CCF Total ~ Btu/ft /hr
E 50 .8 29 1 1160
W 50 .8 29 1 1160 2320 Btu/hr
Beps_______________
N 51 .8
S 51 .8
8
49
1 326
1 1999
2325 Btu/hr
58


Cooling (June Sept.)
Q/tJ. ,, = A x Sc x MSHG x CLF x CCF
(Btu/hr)
A = area of glass
SC = shading coefficient
2
MSHG = maximum solar heat gain (Btu/ft /hr) CLF = cooling load factor CCF = cloud cover factor
Chimney Hills Beps n
A 101 f tz (2 walls) 102 ft (2 walls)
SC .52 (given) .45 (given)
MSHG See table 7 See table 7
CLF See table 8 See table 8
CCF .9 (given) .9 (given)
Chimney Hills
Wall A SC MSHG CLF CCF Q (Btu/hr)
E 50 .52 213 .23 1 1274
W 50 .52 213 .23 1 1274 2548 Btu/hr
Beps
Wall A SC MSHG CLF CCF Q (Btu/hr)
N 51 .45 38 .48 1 419
S 51 .45 138 .27 1 855
1274 Btu/hr
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FLOOR
Heating (October May)
Q/T.J- /u > = U x A x T (Btu/hr)
U = Overall Heat Transfer Coefficent
A = Area of floor
At = Difference between indoor and outdoor temperature
U=It
Chimney Hills Beps
Element Resistance (R-value) Resistance (R-value)
Outside Surface .17 .17
Materials
3/4" plywood .93 .93
carpet with
rubber pad 1.23 1.23
4" concrete .80 .80
vapor barrier .06 .06
Inside Surface .61 .61
Total Rt 3.80 Rt 3.80
__ 1 _o 1 0
U 3.80 = .26 Btu/hr/ft /F 3.80 = .26 Btu/hr/ft /F
A = 915 680
/}T = -29 -29
Q = .26(884) (-29) = -6665 Btu/hr .26 (680) (-29) = -5127 Btu/hr
Cooling
If the floor is directly on the ground or over an unheated or unventilated basement, this need not be calculated. There is an unheated garage beneath the unit.
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INFILTRATION
Heating (October May)
^(Btu/hr) = .018 x Ac x Ft3 x T Sensible heat gain
Ac air changes per hour
AT difference between indoor and outdoor temperature
Chimn ey Hills Beps
Ac .9 Ac .7
Ft3 11492 Ft3 10890
/) T 29 4T 29
Q = . 018 x .9 x 11,492 Q = .018 x .7 x 10890 x
x (-29) = -5,399 Btu/hr -3979 Btu/hr
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Cooling (June Sept)
3
^Btu/hr) = .018 x Ac x Ft x T (Sensible)
Ac = air changes per hour
&T = difference between indoor and outdoor temperature
Chimney Hills Beps
Ac 1.0 Ac 1.0
Ft3 11492 Ft3 10890
Q T 2 <0 T 2
Q = .018 x .9 x 11492 x 2 = Q = .018 x .7 x 10890
372 Btu/hr 274 Btu/hr
Latent heat gain Q(Btu/hr)
W = .001 (given)
Chimney Hills Q = 79.5 x .9 x 11492 x .001 = 822 Btu/hr
Total 1194 Btu/hr
= 79.5 x Ac x Ft3 x W (Latent) Beps
Q = 79.5 x .7 x 10890 x .001 = 606 Btu/hr
Total 880 Btu/hr
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INTERNAL LOADS
Heating and Cooling
This information is set by Beps at a given level which varies only slightly by the size of the structure. Please see comments following this section for further explanations.
Chimney Hills Beps
+2288 Btu/hr +2276 Btu/hr
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TABLE IV SPACE HEATING AND COOLING DEMAND
SF DETACHED
HEATING COOLING
CATEGORY Beps SH Diff Beps SH Diff REASONS
Roof/Ceiling - 580 - 688 + 108 + 400 + 514 + 114 Insulation R-38 Beps, R-30 Sh
External Walls -2044 -3538 -1494 + 804 + 1354 + 550 1) Insulation R-19 Beps, R-21 Sh 2) Area det. more area than att.
Slass (transmission) -1256 -1540 + 284 + 54 + 60 + 6 Glazing Beps-Triple, Sh-double
31ass (solar) +2766 +2088 + 678 + 1865 +2064 + 199 Orientation Beps 4 sides, Sh-2 sides
Eloor -6032 -6434 + 402 Area Beps a little laraer
Infiltration -6890 -7907 +1017 + 1524 +1749 + 225
Internal Load +2358 +2334 + 24 +2358 +2334 - 24
TOTAL (Btu/ftVhr) -11678 -15685 4007 +7005 + 8075 1070


TABLE V SPACE HEATING AND SF ATTACHED COOLING DEMAND
HEATING COOLING
CATEGORIES Beps CH Diff. Beps CH Diff. REASONS FOR DIFFERENCES
Roof/Ceiling - 493 -1168 + 675 + 340 + 787 + 447 1) Insulation R-38 Beps, R-21 Ch 2) Area Ch has larger area
External Walls - 685 -1230 + 545 + 226 + 598 + 372 1) Insulation R-38 Beps, R-llCh 2) Area att. less area than det.
Glass (transmis- -1125 -1680 + 555 + 46 + 65 + 19 Glazinq Bepstriple, Ch-double
sion)
Glass (solar) +2325 +2320 + 5 + 1274 +2548 + 1274 Orientation-Beps glass on 4 walls
Ch glass on 2 walls
Floor -5127 -6665 + 1538 Area Beps has small area
Infiltration -3979 -5399 + 1420 + 880 +1194 + 314 Area more exposure to outside air
Internal Load +2276 +2288 - 12 +2276 +2288 + 12
TOTAL (Btu/f t2/hr) -6808 -11534 4726 + 5042 +7480 2438


COMMENTS
The following are comments regarding each category and calculation. These comments refer both to the explanations of the data itself and to the causes of major differences between the various models.
ROOF/CEILING Notes
As all models insulated the ceiling rather than the roof and have unheated crawl space between the 2nd floor and roof only the structural material of the ceiling is important here in determining heat loss.
Differences
The main reasons Chimney Hills ceiling load is so much higher than the other three models are that it has a large ceiling area and its insulation at R-21 is considerably lower than Smokey Hill's R-30 and Beps R-38.
The area difference is due to the fact that these townhome units are designed in odd shapes with a large first floor area rather than a compactly designed two-story building.
If Chimney Hills had been built with R-21 insulation and built with the same square footage (1404) or a savings of 272 Btu/hr or 23% of the heat lost through the ceiling.
EXTERNAL WALLS Notes
Solar heat gain in the summer is calculated into
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the cooling figures but winter wall heat gain is not.
The methodology used here does not address the issue, and in discussing winter heat gain through walls most experts felt the impact too minimal for the effort involved with a manual audit. Therefore it is not included here. Differences
1. ) Both Denver communities use R-ll insulation
in the walls as compared to R-19 in the Beps models, accounting for large heating load differences between the units.
2. ) The attached housing loses much less energy than conventional housing due to the fact it has only two walls exposed to outside air.
3. ) Orientation plays a relatively minor role here as solar heat gain through walls in the summer is evident but not as insulation levels.
GLASS (TRANSMISSION)
Notes
These calculations refer to the transmission of heat through glass due to temperature differences between the indoors and outdoors. In the winter there is a heat loss through windows and glass doors and in the summer there is a heat gain through glass.
Differences
The main difference here is that the Beps models use triple glazing to reduce the heat loss of the homes.
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GLASS (SOLAR)
Notes
These calculations refer to solar radiation through the glass, both direct and indirect from sunlight. This is heat that is added to the building envelop in both winter and summer months. The amount of radiation varies with orientation, climate, and latitude.
The methodology does not include solar gain through glass in winter months, but since this factor is so crucial to passive solar the calculations have been determined and added to the total heat demand. The calculation method is based on conversations with Marc Schultz, of Mathematical Sciences Northwest Inc. The figures below are based on Denver solar heat gain through vertical double glazing. Both reflection and absorption losses were calculated out. Figures were not available for triple glazing, so for the purposes of this study only double glazing is assumed in solar heat gain.
For heating purposes (Oct. May) the average Btu/ft^/hr
gain is as follows:4
S N E,W
49 8 29
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Differences
There are two differences to note here. The Beps detached home has a much higher heat gain in winter than the local model because Beps has windows in all four directions while Smokey Hills receives solar heat gain from only two directions, neither of which is south. The Beps attached home has a much lower solar heat gain in the summer because it faces north and south and does not pick up as much heat gain as windows facing east and west (when combined).
FLOORS
Notes
The insulation level of the floor in the Beps models was not specified and the building information used was based on a memo from Lawrence Berkeley Labs (Goldstein, Levine, and Mass). The differences between Beps and the Denver area practices may be greater, however, if no heat loss is assumed through the floor as is being assumed. This would greatly alter the Beps model. Differences
The Beps attached model is lower than the other three models in heat loss. Again, this is because that particular model has a smaller floor area. This is discussed further in the section on design.
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INFILTRATION
Notes
Infiltration is a major concern in determining energy demand. It affects heat losses due to the leakage of air from the outside. It is caused by pressure differences in the air between inside and outside and its extent can be greatly affected by 1) wind speed and direction,
2) temperature differences between in and out doors, and
3) the tightness of the building.
Thus infiltration is important because it can alter drastically the amount of energy needed to heat and cool a home. It can be controlled not only by the tightness of the building but by many site planning principles such as building orientation, landscaping, etc.
The appropriate air change per hour rates, however, were difficult to assess. In the Beps method their typical house, which assumes tight windows and doors with normal caulking, has an air change rate of .6. The methodology used in this study suggests air change rates of 1.0 1.5 with "tight" homes using the 1.0 figure. The DOE method appears to use a more sophisticated equation which might include variables not considered in the methodology used in this study. Therefore, I compromised between the two.
For the detached Denver area homes I used 1.2 AC because some caulking does exist but the buildings are not considered especially tight. For the Beps model I used
70


1.0 as the model is built "tight".
For the townhome model, since less wall, window, roof space is exposed to outside air I lowered the infiltration rate using .9 AC for the Denver home and .7 for Beps.
It should also be noted that these homes are all assumed or known to have no windbreaks with much effect. Differences
The major reasons for the differences between the Beps and the local models as well as the differences between all detached and attached models are the air change rates explained in detail above and the varying volume figures.
INTERNAL LOADS Notes
This figure represents the estimated waste heat, or internal load, added to the building by people, appliances, and lighting. This waste heat can be large enough to affect heating and cooling loads, especially if the house is tight.
While there are many methodologies which determine the internal load for each of these items, and the amount will differ greatly with the number of occupants, appliances, and the tightness of the house, DOE established a fixed amount for each residential unit, based on indepth studies. This figure varies only with the size of the house
71


as more lighting per square foot will be necessary.
The basis for the internal load used for these homes is 3.2 persons/h.h. with "average" appliances such as refrigerator, stove, oven, freezer, water heater, T.V., washer and dryer, dishwasher, and miscellaneous small appliances.
Beps estimates that approximately 1808 Btu/hr
for people and appliances is added to the internal load
2
of a house. Lighting adds approximately .3435 Bru/ft /hr
5
to the load.
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Annual Thermal Load
The total hourly demand figures were then converted to annual amounts, again based on given equations and information. These annual consumption figures are then added to water demand, which is a fixed amount for each residential unit. See Tables 6 and 7. These tables demonstrate the total consumption figures and the amount of difference between the models. As can be seen, when just looking at space heating and cooling, the Beps level in detached homes could be as high as 28% over Denver standards, and 38% above Denver standards in the attached unites. When including water heating, the amount of difference is considerably less, 21-23%.
The following lists the assumptions made on the variables pertaining to the annual thermal load as determined on the next few pages.
HEATING
Notes
The annual heating degree days, hours of operation, and the efficiency of the furnace are all given in the Beps methodology.
COOLING
Notes
The Beps methodology assumes that people will use natural ventilation to cool their homes whenever possible, thus an 8 hour operating time was used.
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N
The cooling load is determined for the months June through September. It is assumed that since June and September both experience many days cooler than 80 degrees and that people are out of their house more and the air conditioner would not be operating each day. Therefore 80 days was used for the number of days cooling might be needed.
E -
The efficiency of the air conditioner is provided
by Beps.
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SINGLE FAfllLY DETACHED
Heating (October May)
XH x DP x Hrs (Btu/hr) (65-Toa x E)
XH = Heating Load (Btu/hr) (from load summation table) reg. type
DD = Annual heating degree days
Hrs = hours per day that heating system is operating Toa = average outside temperature E = efficiency of furnace
Smokey Hills
Xh = 15,685 Btu/hr DD = 4246 Hrs = J6 Toa = 41
E = .7
^ (Btu/hr)
15,685 x 4246 x 16 = 41,500 Btu/ft2/yr (65-41) x .7
Beps
Xh = 11,678 Btu/hr DD = 4246 Hrs = 16 Toa = 410 E = .7
Q(Btu/hr)
11,678 x 4246 x 16 = 29,500 Btu/ft2/yr (65-41) x .7
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Cooling (June Sept)
Q (Btu/hr)
Xc x N x Hrs E
Xc = Cooling load from Table
N Number of days per year that the cooling system is operating
Hrs = Number of hours per day that the cooling system is operating (does not include setup hours)
E = Efficiency of the air-conditioner
Smokey Hills Xc = 8075 Btu/hr
Beps
Xc = 7005 Btu/hr N = 80 Hrs = 8 E = .7
Q(Btu/hr) = 7005 x 80 x 8 = 4000 Btu/ft2/yr
N = 80
Hrs = 8
E = .7
(Btu/hr)
8075 x 80 x 8 = 4,800 Btu/ft2/vr .7
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SINGLE FAMILY ATTACHED
Heating (October May)
= Xh x DD x Hrs
(Btu/hr)
(65 Toa) x E
Xh = Heating load (Btu/hr) (from load summation table) reg use
DD = Annual heating degree days
Hrs = hours per day that heating system is operating Toa = average outside temperature E = efficiency of furnace
Chimney Hills Xh = 11534 Btu/hr DD = 4246 Hrs = 16 Toa = 41
E = .7
Q;t_ 4 = 11534 x 4246 x 16 = 33,200 Btu/ft2/yr
tiitu/nr; (65-41) x .7
Beps
Xh = 6808 DD = 4246 Hrs = 16 Toa = 410 E = .7
Q (Btu/hr) SS-g? * 16 ,20.200 Btu/ft2/yr
' (65-41) x .7
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Cooling (June Sept)
Q(Btu/hr)
Xc x N x Hrs E
Xc = Cooling load from Table
N = Number of days per year that the cooling system is operating
Hrs = Number of hours per day that the cooling system is operating (does not include setup hours)
E = Efficiency of the air-conditioner
Chimney Hills Xc = 7480 Btu/hr
Beps
Xc = 5042 Btu/hr N = 80 Hrs = 8 E = .7
Q(Btu/hr) = 5042 x 80 x 8 = 3400 Btu/ft2/yr
7
N = 80
Hrs = 8
E = .7
Q(Btu/hr)
7480 x 80 x 8 = 4900 Btu/ft^/yr .7
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TABLE VI
DESIGN ENERGY BUDGETS
SF DETACHED (Btu/ft/yr)
Smokey Hills Beps Difference
Heating 41,500 29,500 +11,000
Cooling 4,800 4,000 + 800
Subtotal 46,300 33,500 +12,800 (28%)
Water 19,300 18,400 + 900
TOTAL 65,600 51,900 +13,700 (21%)
TABLE VII - DESIGN ENERGY BUDGETS
SF ATTACHED (Btu/ft^/yr)
Chimney Hills Beps Difference
Heating 33,200 20,200 +13,000
Cooling 4,900 3,400 + 1,500
Subtotal 38,100 23,600 +14,500 (38%)
Water 21,000 21,700 700
TOTAL 59,100 45,300 +13,800 (23%)
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Table VIII shows the comparison of the Design Energy Budget established by DOE for Beps to those established by the methodology used in this study. This is done only for informational purposes. It was not the intention of this study to evaluate and compare the manual methodology used here to DOE's choice of a computer method and no comparison is made. Despite the closeness of the Design Energy Budgets there were decisions made on certain calculations, especially infiltration and solar heat gain, that while based on Bept information and advice, may have altered the final figures. Therefore it cannot be assumed that the manual audit used here would be an acceptable substitute for the computer program. It does, however, seem to warrant further studying for this possibility as the levels were relatively close and may only require minor adjustments in the calculations.
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Water
A few comments need to be made regarding water demand. As explained earlier, the energy demand for hot water usage is calculated separately from space heating and cooling. It is a fixed amount for each residential unit, 29,500,000 btu/yr., and is not altered by the number of occupants. The only factor besides size which does affect the Design Energy Budget is the rating factor for each fuel type-natural gas, electricity or oil, which is applied to the given 29,500,000 level. All models here used natural gas so the Energy Budget Level for hot water heating remains at 29,500,000 btu/yr.
In order to add this figure to the final Design Energy Budget, the 29,500,000 must be divided by the square footage of each dwelling unit. Below are the four models, their square footage, and the btus/ft /yr:
Ft2 Btu/ft2/yr.
Chimney Hills Townhomes 1404 Beps Townhomes 1360 Smokey Hills Detached 1530 Beps Detached 1600
21,011
21,691
19,281
18,438
These figures appear to be very generous on water heating. According to Denver Residential Energy Consumption by Hittman & Associates in 1976 the estimate for water heating in existing buildings was 18,000 btu/ft /yr and if increased insulation is added to the water heated this could be reduced to 15,000 btu/ft /yr. Although estimating hot water demand is new and not well established and DOE is looking at developing more accurate estimating
81


techniques, the calculations used here are probably quite lenient and do allow quite a bit of flexibility for the builder.
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CHAPTER IV POTENTIAL ENERGY SAVINGS
Once the audits were complete it was possible to determine the potential energy savings from various energy conservation measures. These savings are identified and described in this chapter. Combinations of measures are established which would achieve maximum reduction of energy at reasonable or minimum cost. Also described in this chapter are site planning principles whose importance in helping to reduce energy costs are evident from the results of this study.
It was necessary to understand how various energy conservation measures would effect the energy demand of both types of homes. Each item (insulation, orientation, etc.) is changed to meet a given standard by substituting certain building characteristics and site orientation measures into the appropriate equations in the audit. This determines the potential savings for any particular change. The following section takes each measure and changes whatever variable is being tested, resulting in the savings if only one item is changed. Table 9 reflects the total findings of this analysis. Brief explanations of each measure, how and why it was altered, and the individual savings produced follow.
It is important to note that these findings will vary from site to site and are estimates only.
The criteria for these changes were 1) recommendations and/or basis for Energy Budget Levels of Beps, and
2) site planning principles which would not greatly affect the cost of development.
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TABLE IX
TOTAL POTENTIAL ENERGY SAVINGS OF DENVER HOMES
DETACHED ATTACHED
2 2 Btu/ft/yr % Space, % Space Btu/ft/yr % Space, % Space
Saveci Water h&c h&c Saved Water h&c h&c
Insulation (R-38 ceiling) (R-19 walls) 4,700 7.2 10.2 3,200 5.4 8.4
Triple Glazing 1,500 2.3 3.2 1,600 2.7 4.2
Infiltration 3,700 5.6 8.0 3,600 6.1 9.4
Site Orientation 5,400 8.2 11.7 5,200 8.8 13.6
Landscaping (Windbreaks) 6,100 9.2 13.2 3,100 5.2 8.1
Design 4,800 8.1 12.6
TOTAL 21,400 32.5 46.3 21,500 36.4 56.3


TABLE X. COMPARISONS OF POTENTIAL REDUCTIONS
SPACE HEATING/COOLING AND WATER HEATING
UNIT POTENTIAL MINIMUM LIMIT (Btu/ft vyr.) % REDUCTION
SH-SFD 44,200 32.5%
CH-SFA 37,200 37%
Beps-SFD 44,200 15%
Beps-SFA 37,200 17%

TABLE XI. COMPARISONS OF POTENTIAL REDUCTIONS
SPACE HEATING AND COOLING
UNIT POTENTIAL MINIMUM LIMIT (Btu/ft2/yr.) % REDUCTION
SH-SFD 24,900 46%
CH-SFA 16,600 56%
Beps-SFD 24,900 26%
Beps-SFA 16,600 30%
^ 2
Tables X and XI reflect the potential reduction in Btu/ft if all
measures in Table IX are taken. As shown in Table X, this can result in a total reduction of 32-37% for Denver area homes and an additional
15-17% for the Beps models. Table XI demonstrates total reduction in space heating and cooling alone.
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The three main factors which reflect the dif-
ferences between the Beps and the Denver models are higher levels of insulation, triple glazing of windows and doors, and improved infiltration due to good weatherstripping and caulking practices. These, of course, were the factors which Beps used intentionally to reduce energy consumption. Each item is reviewed below.
INSULATION
If the Denver models used ceiling insulation levels of R-38 and wall insulation levels of R-19, with all other factors remaining the same, the savings would be as follows:
SF DETACHED __________
TABLE XII POTENTIAL HOURLY SAVINGS FROM MORE INSULATION Btu/ft/hr % heating % saved saved cooling saved
Ceilings h 133 .8
(R-38) c 131 1.6
Walls h 1518 9.7
(R-19) c 570 7.1
Totals h 1651 10.5
c 701 8.7
TABLE XIII POTENTIAL ANNUAL ENERGY SAVINGS
CEILING & WALLS COMBINED
Btu/ft2/yr % Total
Heating 4,300 6.6
Cooling 400 .6
Total 4,700 7.2
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SF ATTACHED
TABLE XIV POTENTIAL HOURLY ENERGY SAVINGS FROM MORE INSULATION
Btu/ft/hr % heating % cooling
saved saved saved
Ceiling h 505 4.4
(R-38) c 329 4.4 I
Walls h 463 4.0
(R-19) c 231 3.0 1
Totals h 968 8.4
c 560 7.4 1
POTENTIAL ANNUAL ENERGY SAVINGS
CEILINGS & WALLS COMBINED
Btu/ft2/vr % Total
Heating 2,800 4.7
Cooling 400 .7
Total 3,200 5.4 1
TRIPLE GLAZING
Neither Denver area model used triple glazing
of windows and glass doors. The chart below demonstrates the savings in glass transmission from triple glazing if all other factors remained the same.
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TABLE XV POTENTIAL ENERGY SAVINGS I FROM TRIPLE GLAZING I
^Hourly ^Annual
Btu/ft/hr % h or c Btu/ftvyr % total 1
Heating 574 3.7 1,500 2.3 I
Cooling -18 .2 Negl. Negl 1
Total 3.9 1,500 2.3 1
Attached I
^Hourly 0Annual
Btu/ftVhr % h or c Btu/ft /yr % total 1
Heating 566 4.9 1,600 2.7 1
Cooling 20 Negl. Negl. I
Total 1,600 2.7 I
INFILTRATION
Infiltration rates also vary between Beps and Denver area models. If incorporated into the program both Beps and Denver models would reduce energy consumption. Below are estimations of savings of infiltration losses if improved building practices existed for these homes.
TABLE XVI POTENTIAL ENERGY SAVINGS
FROM IMPROVED BUILDING Btu/ft^/hr % h or c "TIGHTNESS" Btu/ft2/yr % total
Heating 1,318 00 0* 3,500 5.3
Cooling 291 3.6 200 .3
Totals 3,700 5.6

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Btu/ft^/hr Attached % h or c Btu/ft2/vr % total
Heating 1,200 10.4 3,400 5.8
Cooling 264 3.5 200 .3
Totals 3,600 6.1
The following measures relate to design and site planning principles.
SITE ORIENTATION
To determine the effect of an orientation toward the south, revisions were made on those calculations addressing window and wall orientation toward the south, namely heat gain through glass (solar), heating and cooling, and heat gain through walls, cooling only. This includes consideration of shading through landscaping as well.
South Facing Walls
The fact that long sides of buildings should face south is because solar radiation can penetrate walls to heat homes. However, the methodology used in this study does not incorporate heat gain through walls during heating seasons. In speaking with people who helped develop the audit and those familiar with other audits, computer systems are necessary in order to calculate accurate figures. Manual methodologies would require great detail and complexity to determine small percentages to the overall product.
89


Therefore this study does not directly address and include solar heat gain through walls during winter.
On the following pages the new demand figures for these separate categories are shown, followed by the amount of savings that results from each category and the three combined. The assumptions made here are that the front or back of a building face south, additional glass area faces south, and landscaping of decidious trees allows for moderate protection from sunlite in the summer and increased sunlight in the winter.
I TABLE XVII SOLAR HEAT GAIN FROM SOUTH EXPOSURE
(SF Detached)
Hourly Heat Gain Btu/ft2/hr % Annual Heat Gain h & c Btu/ft /yr total %
I Heating I glass 1 50ft^N 1 100ft2S + 2120 13.5 5,600 8.5
I Cooling I glass I Cooling 1 wall I 50 ftN 1 100 ft2S - 301 - 92 - .5 - 200 -.3
1 Total 1,727 13.0 5,400 8.2
1 TABLE XVIII I (SF Attached)
1 Heating I glass 8 50ft^N 1 100ft2S +1920 16.6 5,500 9.3
8 Cooling 8 glass 8 Cooling 8 wall 8 Tnt.a 1 - 136 - 263 - qqq - .3 16.3 - 300 .5 8.8


LANDSCAPING
Another major site planning principle is the use of windbreaks to cut infiltration rates and thus reduce heat and cooling losses through cracks and through building material. These windbreaks can be other building structures, fences, or trees and bushes. Their location, size, and type all affect the amount of protection provided to a building and these will be discussed later.
In the charts that follow, the columns marked combined refer to the reduction of both tight building practices and proper landscaping together. This is done because the two measures work hand in hand. Landscaping alone, of course, refers just to the energy reduction from buffering.
The potential effects of proper landscaping will be applied to Smokey Hills and Chimney Hills to determine the energy savings. The Beps methodology states that the infiltration air change rate can be reduced at least 1/3 by good landscaping practices. If the homes were already tight not as much reduction in the air change rate would occur. Therefore, to calculate energy savings from windbreaks the air change rate in infiltration loads were reduced by 1/3 in Smokey Hills to .67 and by 1/4 in Chimney Hills to .53. It was assumed that Chimney Hills would not be as affected because of the smaller wall exposure. These air changes assume approximately 30% reduction in wind speed.
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Ideally the buildings should be sited so that there is minimum wall exposure toward the wind, which in this case is southwest. That allows for the minimum loss through walls. This could be done by facing the front of homes south-southeast so that sides, with few if any windows, could face southwest. In addition, trees and bushes could be planted in the southwest side of each house to reduce wind velocity.
Wind has been determined to be important to infiltration rates for the following reasons:
1. Wind movement increases the infiltration of cold air through the cracks around doors and windows and even through the building materials themselves.
2. Heat loss due to infiltration is significant because it results in both sensible heat loss (i.e., increased heat required to warm outdoor air entering by infiltration) as well as latent heat loss (i.e., heat equivalent of any moisture which must be added).
' TABLE XIX - POTENTIAL ENERGY SAVINGS USING
LANDSCAPING AS WINDBREAKS
SF DETACHED
Hourly Annual
Btu/ft2/hr % h & c Btu/ft2/yr % total
Heating 2174 13.9 5,800 8.8
Cooling 482 6.0 300 .4
Total 2656 19.9 6,100 9.2
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TABLE XX POTENTIAL ENERGY SAVINGS USING LANDSCAPING AS WINDBREAKS SF ATTACHED
Hourly Btu/ft2/hr % h & c Annual Btu/ft2/yr % total
Heating 1020 Cooling 227 3.0 200 .3
Total 1247 4.9 3,100 5.2
DESIGN
The two townhome models reflect a major difference between their designs and the energy efficiencies that result from design. Chimney Hills has a very inefficient floor plan in that it has a very large first floor with only a small second story. If the unit had been built with equal sized floors there would not be as large a heat loss through floors and ceilings. If the unit were built with equal sized floors, meaning that the first floor would consist of 702 ft^ rather than 915 ft2 272 btu/ft^/hr could
2
be saved through ceiling losses and 372 btu/ft /hr saved through the floor. This results in a combined energy savings of 644 btu/ft /hr or 14.3 reduction in heating needs and 8% energy savings in the total energy demand. Cooling also is reduced but to a lessor degree. Walls would also change somewhat since the units would be built in a conventional rectangular shape. These changes in energy are not reflected here because changes would be offset by more area facing
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each direction, and the differences would be minimal.
DENSITY
One other major item should be mentioned. The advantages of units sharing common walls is quite evident in analyzing the energy demands of the models. By sharing walls units have much less wall space through which to lose heatboth through natural wall heat loss and inefficient caulking and weatherstripping, etc. The table below reflects the possible savings in the Chimney Hills townhomes because they did share common walls with other units. These are savings which already occur in the total energy demands of 59,100 btu/yr. These figures are based on comparisons between the Beps detached and Beps attached units. If the building was also constructed tightly, additional savings of 5/6% could be achieved (see Table IX).
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