NIST Special Publication 1161

Benefits and Costs of Energy 

Standard Adoption in New 

Commercial Buildings: National 

Summary 

Joshua Kneifel 

 

NIST Special Publication 1161

Benefits and Costs of Energy 

Standard Adoption in New 

Commercial Buildings: National 

Summary 

Joshua Kneifel 

Applied Economics Office 

Engineering Laboratory 

May 2013

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary 

National Institute of Standards and Technology 

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director 
Certain commercial entities, equipment, or materials may be identified in this 

document in order to describe an experimental procedure or concept adequately. 

Such identification is not intended to imply recommendation or endorsement by the 

National Institute of Standards and Technology, nor is it intended to imply that the 

entities, materials, or equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Special Publication 1161 

Natl. Inst. Stand. Technol. Spec. Publ. 1161, 134 pages (May 2013) 

CODEN: NSPUE2
Abstract

Energy efficiency requirements in energy codes for commercial buildings vary across 

states, and many states have not yet adopted the latest energy efficiency standard edition. 

As of December 2011, states had adopted energy codes ranging across editions of 

American Society of Heating, Refrigerating and Air-Conditioning Engineers Energy 

Standard for Buildings Except Low-Rise Residential Buildings (ASHRAE) 90.1

(-2001, -2004, and -2007). Some states do not have a code requirement for energy 

efficiency, leaving it up to the locality or jurisdiction to set its own requirements. This 

study considers the impacts that the adoption of newer, more stringent energy codes for 

commercial buildings would have on building energy use, operational energy costs, 

building life-cycle costs, and cradle-to-grave energy-related carbon emissions. 

The results of this report are based on analysis of the Building Industry Reporting and 

Design for Sustainability (BIRDS) database, which includes 12 540 whole building 

energy simulations covering 11 building types in 228 cities across all U.S. states for 9

study period lengths. The performance of buildings designed to meet current state energy 

codes is compared to their performance when meeting new editions of ASHRAE 

90.1-2007 design requirements to determine whether more stringent energy standard 

editions are cost-effective in reducing energy consumption and energy-related carbon 

emissions. Each state energy code is also compared to a “Low Energy Case” (LEC) 

building design based on ASHRAE 189.1-2009, which increases energy efficiency beyond 

the ASHRAE 90.1-2007 design. The estimated savings for each of the building types are 

aggregated using state-level new commercial building construction data to calculate the 

magnitude of the incremental savings that a state may realize if it were to adopt a more 

energy efficient standard as its state energy code. These state-level estimates are further 

aggregated to the national level to estimate the potential total impact from nationwide 

adoption of more stringent energy codes. 

Keywords 

Building economics; economic analysis; life-cycle costing; life-cycle assessment; energy 

efficiency; commercial buildings
vi 
vii 

Preface 

This study was conducted by the Applied Economics Office in the Engineering 

Laboratory (EL) at the National Institute of Standards and Technology (NIST). The 

study is designed to assess the energy use, life-cycle cost, and energy-related carbon 

emissions impacts from the adoption of new state energy codes based on more stringent

building energy standard editions. The intended audience is researchers and policy 

makers in the commercial building sector, and others interested in building energy 

efficiency. 

Disclaimers 

The policy of the National Institute of Standards and Technology is to use metric units in 

all of its published materials. Because this report is intended for the U.S. construction 

industry that uses U.S. customary units, it is more practical and less confusing to include 

U.S. customary units as well as metric units. Measurement values in this report are 

therefore stated in metric units first, followed by the corresponding values in U.S. 

customary units within parentheses. 
viii 
ix

Acknowledgements

The author wishes to thank all those who contributed ideas and suggestions for this 

report. They include Dr. David Butry, Ms. Barbara Lippiatt, and Dr. Robert Chapman of 

EL’s Applied Economics Office, Dr. William Healy of EL’s Energy and Environment 

Division, and Dr. Nicos S. Martys of EL’s Materials and Structural Systems Division. A 

special thanks to Mr. Nicholas Long and the EnergyPlus Team for generating the initial 

energy simulations for this project. Thanks to Mr. Brian Presser for adapting the energy 

simulations to meet the study requirements and generating the final simulations used in 

the database. Thanks to Mr. Nathaniel Soares for developing the initial version of the 

BIRDS database, and to Ms. Priya Lavappa for enhancing the database for the current 

analysis. 

Author Information

Joshua D. Kneifel 

Economist 

National Institute of Standards and Technology 

Engineering Laboratory 

100 Bureau Drive, Mailstop 8603 

Gaithersburg, MD 20899-8603

Tel.: 301-975-6857 

Email: joshua.kneifel@nist.gov 
x
xi 

Table of Contents

Abstract .............................................................................................................................. v

Preface .............................................................................................................................. vii

Acknowledgements .......................................................................................................... ix

Author Information ......................................................................................................... ix

List of Figures ................................................................................................................. xiii

List of Tables ................................................................................................................... xv

List of Acronyms ............................................................................................................ xix

Executive Summary ....................................................................................................... xxi

1 Introduction ............................................................................................................... 1

1.1 Background .......................................................................................................... 1

1.2 Literature Review ................................................................................................. 1

1.3 Purpose ................................................................................................................. 3

1.4 Approach .............................................................................................................. 3

2 Study Design .............................................................................................................. 5

2.1 Building Types ..................................................................................................... 5

2.2 Building Designs .................................................................................................. 6

2.3 Study Period Lengths ........................................................................................... 9

3 Cost Data.................................................................................................................. 11

3.1 First Costs ........................................................................................................... 11

3.2 Future Costs........................................................................................................ 14

4 Building Stock Data ................................................................................................ 17

4.1 Databases ............................................................................................................ 17

4.2 Weighting Factors .............................................................................................. 17

5 Analysis Approach .................................................................................................. 19

5.1 Energy Use ......................................................................................................... 19

5.2 Life-Cycle Costing ............................................................................................. 19

5.3 Carbon Assessment ............................................................................................ 20

5.4 Analysis Metrics ................................................................................................. 21

5.5 Regression Analysis ........................................................................................... 23

6 Nationwide Impacts of Adopting Low Energy Case Design ............................... 25

6.1 Percentage Changes............................................................................................ 25

6.1.1 Results by Study Period Length ................................................................ 25

6.1.2 Results by Building Type.......................................................................... 28

6.1.3 Results by Climate Zone ........................................................................... 29

6.1.4 Results by State Energy Code ................................................................... 33

6.1.4.1 Energy Use, Energy Cost, and Carbon Emissions Savings ....... 35

6.1.4.2 Life-Cycle Cost Savings ............................................................ 40

6.2 Total Changes ..................................................................................................... 41

6.2.1 State-Level Total Savings ......................................................................... 41

6.2.2 Regional and National Total Savings ....................................................... 43

6.3 Changes per Unit of Floor Area and Energy Use Savings ................................. 44

6.3.1 State Level Changes .................................................................................. 44
xii 

6.3.1.1 Energy Use Savings per Unit of Floor Area.............................. 44

6.3.1.2 Life-Cycle Cost Savings per Unit of Floor Area ....................... 45

6.3.1.3 Energy Cost Savings per Unit of Energy Use Savings ............. 46

6.3.1.4 Carbon Emissions Savings per Unit of Energy Use Savings .... 48

6.3.2 Regional and National Level Changes ...................................................... 50

6.4 Within-State Impacts of Adopting Low Energy Case Design ........................... 53

6.4.1 Energy Use Savings across Cities ............................................................. 53

6.4.2 Life-Cycle Cost Savings across Cities ...................................................... 57

7 Nationwide Impacts of Adopting ASHRAE 90.1-2007......................................... 63

7.1 Percentage Changes............................................................................................ 63

7.1.1 Results by Study Period Length ................................................................ 63

7.1.2 Results by Building Type.......................................................................... 66

7.1.3 Results by Climate Zone ........................................................................... 67

7.1.4 Results by State Energy Code ................................................................... 70

7.2 Total Changes ..................................................................................................... 74

7.2.1 State-Level Total Savings ......................................................................... 74

7.2.2 Regional and National Total Savings ....................................................... 77

7.3 Changes per Unit of Floor Area and Energy Use Savings ................................. 78

7.3.1 State Level Changes .................................................................................. 78

7.3.1.1 Energy Use Savings per Unit of Floor Area.............................. 78

7.3.1.2 Life-Cycle Cost Savings per Unit of Floor Area ....................... 79

7.3.1.3 Energy Cost Savings per Unit of Energy Use Savings ............. 79

7.3.1.4 Carbon Emissions Savings per Unit of Energy Use Savings .... 82

7.3.2 Regional and National Level Changes ...................................................... 84

8 Incremental Impacts from Adopting More Stringent Standard Editions ......... 87

8.1 Energy Use Savings ........................................................................................... 87

8.2 Life-Cycle Cost Savings..................................................................................... 89

9 Discussion................................................................................................................. 93

9.1 Key Findings ...................................................................................................... 93

9.1.1 Percentage Changes .................................................................................. 93

9.1.2 Total Changes ........................................................................................... 95

9.1.3 Change per Unit of Floor Area ................................................................. 96

9.1.4 Incremental Changes from Adopting More Stringent Standard Editions . 97

9.2 Limitations and Future Research........................................................................ 97

References ...................................................................................................................... 101

A Building Type, New Construction, and Emissions Rates .................................. 105

B Percentage Changes by Building Type for the Nationwide Adoption of the LEC 

Design ................................................................................................................. 111

C Total Changes from Nationwide Adoption of the LEC Design ........................ 121

D Percentage Changes by Building Type for the Nationwide Adoption of the 

ASHRAE 90.1-2007 Design ............................................................................... 127

E Total Changes from Nationwide Adoption of the ASHRAE 90.1-2007 Design 131
xiii 

List of Figures 

Figure 2-1 State Commercial Energy Codes ..................................................................... 8

Figure 2-2 Cities and ASHRAE Climate Zones ................................................................ 9

Figure 6-1 Nationwide Average Percentage Change in Life-cycle Costs from Nationwide 

Adoption of the LEC Design by Building Type and Study Period Length ... 28

Figure 6-2 States with Energy Standard Editions 2001 or Older or No energy code ...... 34

Figure 6-3 Average Energy Use, Energy Cost, and Carbon Emissions Savings by State, 

3-Story Office Building, 10-Year .................................................................. 36

Figure 6-4 Total Energy Use – High School – Tennessee ............................................... 38

Figure 6-5 Change in Energy Use – High School – Tennessee ....................................... 39

Figure 6-6 Percentage Change in Energy Use – High School – Tennessee .................... 39

Figure 6-7 Average Life-Cycle Cost Savings by State, 3-Story Office Building, 10-Year

 ....................................................................................................................... 40

Figure 6-8 Average Annual New Floor Area by State .................................................... 41

Figure 6-9 Total Energy Use, Energy Costs, and Carbon Emissions Savings by State, 

10-Year .......................................................................................................... 42

Figure 6-10 Total Life-Cycle Cost Savings by State, 10-Year ........................................ 43

Figure 6-11 Energy Use Savings per Unit of Floor Area by State, 10-Year ................... 45

Figure 6-12 Life-Cycle Cost Savings per Unit of Floor Area by State, 10-Yr ................ 46

Figure 6-13 Energy Cost Savings per Unit of Energy Use Savings and Average 

Electricity Price by State ............................................................................... 47

Figure 6-14 Weighted Average Offset by State ............................................................... 48

Figure 6-15 Average State Energy Cost Savings per Unit of Energy Use Savings by 

Weighted Average Offset and Energy Price Differential .............................. 48

Figure 6-16 Energy-related Carbon Emissions Savings per Unit of Energy Use Savings 

and Average Electricity Emissions Rate by State .......................................... 49

Figure 6-17 Average State Carbon Emissions Savings per Unit of Floor Area by 

Weighted Average Offset and Energy Emissions Rate Differential ............. 50

Figure 6-18 Average Percentage Change in Energy Use by City - Texas ....................... 53

Figure 7-1 States with Energy Code based on ASHRAE 90.1-2001 or No Energy Code 71

Figure 7-2 States with Energy Code based on ASHRAE 90.1-2007 (Shown in Gray) .... 71

Figure 7-3 Average Energy Use Savings by State, 3-Story Office Building, 10-Year ... 73

Figure 7-4 Average Life-Cycle Cost Savings by State, 3-Story Office Building, 10-Year

 ....................................................................................................................... 74

Figure 7-5 Average Annual New Floor Area by State .................................................... 75

Figure 7-6 Total Energy Use, Energy Cost, and Carbon Emissions Savings by State, 

10-Year .......................................................................................................... 76

Figure 7-7 Total Life-Cycle Cost Savings by State, 10-Year .......................................... 77

Figure 7-8 Energy Use Savings per Unit of Floor Area by State, 10-Year ..................... 79

Figure 7-9 Life-Cycle Cost Savings per Unit of Floor Area by State, 10-Yr .................. 79

Figure 7-10 Energy Cost Savings per Unit of Energy Use Savings and Average 

Electricity Price by State ............................................................................... 80

Figure 7-11 Weighted Average Offset by State ............................................................... 81

Figure 7-12 Average State Energy Cost Savings per Unit of Energy Use Savings by 

Weighted Average Offset and Energy Price Differential .............................. 82
xiv 

Figure 7-13 Energy-related Carbon Emissions Savings per Unit of Energy Use Savings 

and Average Electricity Emissions Rate by State .......................................... 83

Figure 7-14 Average State Carbon Emissions Savings per Unit of Energy Use by 

Weighted Average Offset and Energy Emissions Rate Differential ............. 84

Figure 8-1 Incremental Energy Use Savings by State and Standard Edition .................. 89

Figure 8-2 Incremental Life-cycle Cost Savings by State and Building Design ............. 92
xv

List of Tables 

Table 2-1 Building Characteristics .................................................................................... 5

Table 2-2 Energy Code by State and City Exception ........................................................ 7

Table 3-1 Energy Efficiency Component Requirements for Alternative Building Designs

 ....................................................................................................................... 12

Table 3-2 Energy Efficiency Component Requirements for the ASHRAE 90.1-2007, 

ASHRAE 90.1-2010, and LEC Designs ......................................................... 13

Table 3-3 HVAC Energy Efficiency Requirements for Alternative Building Designs ... 13

Table 4-1 New Commercial Building Construction (U.S., 2003 through 2007) .............. 18

Table 5-1 Greenhouse Gas Global Warming Potentials .................................................. 21

Table 6-1 Nationwide Average Percentage Change in Energy Use from Adoption of the 

LEC Design by Building Type ...................................................................... 25

Table 6-2 Nationwide Average Percentage Change in Energy Costs from Adoption of 

the LEC Design by Building Type and Study Period Length ....................... 26

Table 6-3 Nationwide Average Percentage Change in Carbon Emissions from Adoption 

of the LEC Design by Building Type ............................................................ 27

Table 6-4 National Average Percentage Change in Life-Cycle Costs from Adoption of 

the LEC Design by Building Type and Study Period Length ....................... 27

Table 6-5 Nationwide Average Percentage Change for Adoption of the LEC Design by 

Building Type, 10-Year ................................................................................. 29

Table 6-6 Average Percentage Change in Energy Use for LEC by Climate Zone and 

State Energy Code ......................................................................................... 30

Table 6-7 Average Percentage Change in Energy Costs for LEC by Climate Zone and 

State Energy Code, 10-Year .......................................................................... 31

Table 6-8 Average Change in Energy-related Carbon Emissions for LEC by Climate 

Zone and State Energy Code ......................................................................... 32

Table 6-9 Average Percentage Change in Life-Cycle Costs for LEC by Climate Zone and 

Study Period................................................................................................... 33

Table 6-10 Average Percentage Change by State, 3-Story Office Building, 10-Year .... 35

Table 6-11 Fuel Source Reduction Example ................................................................... 37

Table 6-12 Emissions and Energy Costs Associated with Fuel Source Reductions ....... 37

Table 6-13 Total Reductions by Census Region from Adoption of the LEC Design, 10-

Year ................................................................................................................ 44

Table 6-14 Energy Use Reduction per Unit of Floor Area for Adoption of the LEC 

Design by Census Region, 10-Year ............................................................... 51

Table 6-15 Energy Cost Reduction per kWh of Energy Use Reduction for Adoption of 

the LEC Design by Census Region, 10-Year ................................................ 51

Table 6-16 Carbon Reduction per GWh of Energy Use Reduction for Adoption of the 

LEC Design by Census Region, 10-Year ...................................................... 52

Table 6-17 Life-Cycle Cost Reductions per Unit of New Floor Area for Adoption of the 

LEC Design by Census Region, 10-Year ...................................................... 52

Table 6-18 Variation in Energy Use, Heating Degree Days, and Cooling Degree Days for 

Cities located in Climate Zone 3B in Texas .................................................. 54

Table 6-19 Regression Analysis – Percentage Change in Energy Use from Adopting the 

LEC Design by City ....................................................................................... 56

Table 6-20 Regression Analysis, Within State Variation in Life-Cycle Costs ................ 58
xvi 

Table 6-21 Regression Analysis – Percentage Change in Life-cycle Costs from Adopting 

the LEC Design by City ................................................................................. 60

Table 7-1 Nationwide Average Percentage Change in Energy Use from Adoption of 

ASHRAE 90.1-2007 by Building Type .......................................................... 64

Table 7-2 Nationwide Average Percentage Change in Energy Costs from Adoption of 

ASHRAE 90.1-2007 by Building Type and Study Period Length ................. 64

Table 7-3 Nationwide Average Percentage Change in Carbon Emissions from Adoption 

of ASHRAE 90.1-2007 by Building Type ...................................................... 65

Table 7-4 National Average Percentage Change in Life-Cycle Costs from Adoption of 

ASHRAE 90.1-2007 by Building Type and Study Period Length ................. 65

Table 7-5 Nationwide Percentage Change for ASHRAE 90.1-2007 by Building Type, 

10-Year .......................................................................................................... 66

Table 7-6 Average Percentage Change in Energy Use for ASHRAE 90.1-2007 by Climate 

Zone ............................................................................................................... 67

Table 7-7 Average Percentage Change in Energy Costs for ASHRAE 90.1-2007 by 

Climate Zone, 10-Year .................................................................................. 68

Table 7-8 Average Change in Energy-related Carbon Emissions for ASHRAE 90.1-2007

by Climate Zone ............................................................................................ 70

Table 7-9 Average Percentage Change by State, 3-Story Office Building, 10-Year ...... 72

Table 7-10 Total Reductions by Census Region from Adoption of the ASHRAE 

90.1-2007 Design, 10-Year............................................................................ 78

Table 7-11 Energy Use Reduction per Unit of Floor Area for Adoption of the ASHRAE 

90.1-2007 Design by Census Region, 10-Year ............................................. 84

Table 7-12 Energy Cost Reduction per kWh of Energy Use Reduction for Adoption of 

the ASHRAE 90.1-2007 Design by Census Region, 10-Year ........................ 85

Table 7-13 Carbon Reduction per GWh of Energy Use Reduction for Adoption of the 

ASHRAE 90.1-2007 Design by Census Region, 10-Year .............................. 85

Table 7-14 Life-Cycle Cost Reductions per Unit of New Floor Area for Adoption of the 

ASHRAE 90.1-2007 Design by Census Region, 10-Year .............................. 86

Table 8-1 Incremental Change in Energy Use by State and Building Design, 10-Year .. 87

Table 8-2 Change in Energy Use per Unit of Floor Area by State and Building Design, 

10-Year .......................................................................................................... 88

Table 8-3 Incremental Change in Life-Cycle Cost Reductions by State and Building 

Design, 10-Year ............................................................................................. 90

Table 8-4 Incremental Change in Life-Cycle Cost Reductions per Unit of New Floor 

Area by State and Building Design, 10-Year ................................................ 91

Table A-1 CBECS Categories and Subcategories .......................................................... 105

Table A-2 New Commercial Building Construction Volume for 2003 through 2007 by 

State and Building Type (S-I) ...................................................................... 107

Table A-3 New Commercial Building Construction Volume for 2003 through 2007 by 

State and Building Type (I-P) ...................................................................... 108

Table A-4 New Commercial Building Construction Share by State and Building Type

 ..................................................................................................................... 109

Table A-5 CO2, CH4, and N2O Emissions Rates Electricity Generation by State ......... 110

Table B-1 4-Story Apartment Building Summary Table for LEC and 10-Year Study 

Period ........................................................................................................... 111
xvii 

Table B-2 6-Story Apartment Building Summary Table for LEC and 10-Year Study 

Period ........................................................................................................... 112

Table B-3 4-Story Dormitory Summary Table for LEC and 10-Year Study Period ..... 113

Table B-4 6-Story Dormitory Summary Table for LEC and 10-Year Study Period ..... 114

Table B-5 15-Story Hotel Building Summary Table for LEC and 10-Year Study Period

 ..................................................................................................................... 115

Table B-6 2-Story High School Summary Table for LEC and 10-Year Study Period 116

Table B-7 8-Story Office Building Summary Table for LEC and 10-Year Study Period

 ..................................................................................................................... 117

Table B-8 16-Story Office Building Summary Table for LEC and 10-Year Study Period

 ..................................................................................................................... 118

Table B-9 1-Story Retail Store Summary Table for LEC and 10-Year Study Period . 119

Table B-10 1-Story Restaurant Summary Table for LEC and 10-Year Study Period . 120

Table C-1 Total Reductions by State for Adoption of the LEC Design, 10-Year ......... 121

Table C-2 Energy Use Reduction per Unit of Floor Area from Adoption of the LEC 

Design, 10-Year ........................................................................................... 122

Table C-3 Life-Cycle Cost Reductions per Unit of New Floor Area from Adoption of the 

LEC Design, 10-Year .................................................................................. 123

Table C-4 Energy Cost Reduction per kWh of Energy Use Reduction from Adoption of 

the LEC Design, 10-Year ............................................................................ 124

Table C-5 Carbon Reduction per GWh of Energy Use Reduction from Adoption of the 

LEC Design, 10-Year .................................................................................. 125

Table D-1 4-Story Apartment Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period .................................................................................. 127

Table D-2 6-Story Apartment Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period .................................................................................. 127

Table D-3 4-Story Dormitory Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period................................................................................................. 128

Table D-4 6-Story Dormitory Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period................................................................................................. 128

Table D-5 15-Story Hotel Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period .................................................................................. 128

Table D-6 2-Story High School Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period................................................................................................. 129

Table D-7 8-Story Office Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period .................................................................................. 129

Table D-8 16-Story Office Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period .................................................................................. 129

Table D-9 1-Story Retail Store Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period................................................................................................. 130

Table D-10 1-Story Restaurant Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period................................................................................................. 130

Table E-1 Total Reductions by State for Adoption of the ASHRAE 90.1-2007 Design, 10-

Year .............................................................................................................. 131

Table E-2 Energy Use Reduction per Unit of Floor Area from Adoption of the ASHRAE 

90.1-2007 Design, 10-Year.......................................................................... 132
xviii 

Table E-3 Life-Cycle Cost Reductions per Unit of New Floor Area from Adoption of the 

ASHRAE 90.1-2007 Design, 10-Year .......................................................... 133

Table E-4 Energy Cost Reduction per kWh of Energy Use Reduction from Adoption of 

the ASHRAE 90.1-2007 Design, 10-Year .................................................... 133

Table E-5 Carbon Reduction per GWh of Energy Use Reduction from Adoption of the 

ASHRAE 90.1-2007 Design, 10-Year .......................................................... 134
xix 

List of Acronyms 

Acronym Definition

AEO Applied Economics Office

AIRR Adjusted Internal Rate of Return

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

BIRDS Building Industry Reporting and Design for Sustainability

CBECS Commercial Building Energy Consumption Survey

CH4 Methane

CO2 Carbon Dioxide

CO2e Carbon Dioxide Equivalent

DOE Department of Energy

EEFG EnergyPlus Example File Generator

eGRID Emissions and Generation Resource Integrated Database

EIA Energy Information Administration

EL Engineering Laboaratory

EPA Environmental Protection Agency

FEMP Federal Energy Management Program

FERC Federal Energy Regulatory Commission

HVAC Heating, Ventilating, and Air Conditioning

I-P Inch-Pounds (Customary Units)

IECC International Energy Code Council

ISO International Organization for Standardization

LCA Life-Cycle Assessment

LCC Life-Cycle Cost

LEC Low Energy Case

MRR Maintenance, Repair, and Replacement

N2O Nitrous Oxide

NERC North American Electric Reliability Corporation

NIST National Institute of Standards and Technology

PNNL Pacific Northwest National Laboratory

ROI Return On Investment

S-I System International (Metric Units)

SEER Seasonal Energy Efficiency Ratio

SHGC Solar Heat Gain Coefficient
xx

Acronym Definition

SPV Single Present Value

UPV* Uniform Present Value Modified for Fuel Price Escalation
xxi 

Executive Summary 

Energy efficiency requirements in energy codes for commercial buildings vary across 

states, and many states have not yet adopted the latest energy standard edition. As of 

December 2011, state energy code adoptions range across editions of the American 

Society of Heating, Refrigerating and Air-Conditioning Engineers Energy Standard for 

Buildings Except Low-Rise Residential Buildings (ASHRAE 90.1-2001, -2004, 

and -2007). Some states in the United States do not have a code requirement for energy 

efficiency, leaving it up to the locality or jurisdiction to set its own requirement. There 

may be significant energy and cost savings to be realized by states, particularly those 

states that have not yet adopted an energy code, if they were to adopt more energy 

efficient commercial building energy standard editions. 

The results of this report are based on analysis of all fifty states in the U.S. using the 

Building Industry Reporting and Design for Sustainability (BIRDS) database. BIRDS 

includes 12 540 whole-building energy simulation estimates covering 11 building types 

in 228 cities across all U.S. states for 9 study period lengths. The performance of 

buildings designed to meet current state energy codes is compared to their performance 

when meeting alternative building energy standard editions to determine whether more 

stringent energy standard editions are cost-effective in reducing energy use and 

energy-related carbon emissions. Each state energy code is also compared to a “Low 

Energy Case” (LEC) building design based on ASHRAE 189.1-2009 (Standard for the 

Design of High-Performance Green Buildings Except Low-Rise Residential Buildings), 

which increases energy efficiency beyond the ASHRAE 90.1-2007 design. 

Overall, adoption of ASHRAE 90.1-2007 for the 19 states that have not yet adopted it as 

their state energy code leads to percentage reductions in energy use, energy costs, and 

energy-related carbon emissions. The average percentage reduction in energy use for new 

commercial buildings is 9.6 % while energy costs and carbon emissions realize average 

reductions of 12.2 % and 12.4 %, respectively for a 10-year study period. The reductions 

in energy use and carbon emissions are cost-effective, with average life-cycle costs 

decreasing by 0.7 %.

However, ASHRAE 90.1-2007 does not lead to energy efficiency improvements over 

older editions of ASHRAE 90.1 for all locations in the U.S. for two reasons. First, the 

simplification of the ASHRAE climate zones from 26 zones in ASHRAE 90.1-2001 to 

eight zones in ASHRAE 90.1-2004 resulted in the relaxation of some building envelope 

requirements for some locations. Second, ASHRAE 90.1-2007 has less stringent solar heat 

gain coefficient (SHGC) requirements relative to ASHRAE 90.1-2004 for some climate 

zones. As a result, high-rise, 100 % glazed buildings realize smaller reductions, and 

occasionally increases, in energy use because the less stringent window requirements 
xxii

overwhelm the stricter requirements for other energy efficiency measures analyzed in this 

study. 

Overall, adoption of the LEC design in all 50 states leads to average nationwide 

percentage reductions in energy use, energy costs, and carbon emissions greater than 

those realized by ASHRAE 90.1-2007. The average reduction in energy use is 17.8 % 

over current state energy codes while energy costs and carbon emissions realize average 

reductions of 22.6 % and 20.4 %, respectively. The reductions in energy use and carbon 

emissions are cost-effective, with life-cycle costs decreasing by 1.1 % on average for a 

10-year study period. 

States with current energy codes based on older editions of ASHRAE 90.1 realize greater 

percentage reductions in energy use, energy costs, and carbon emissions for the ASHRAE 

90.1-2007 design. For a small office building, the 13 states with reductions in energy use 

of at least 10 % have no state energy code or have adopted ASHRAE 90.1-2001. For the 

LEC design, 14 of the 18 states that realize reductions in energy use greater than 25 % 

have no state energy code or have adopted ASHRAE 90.1-1999/2001, including all 13 

states with reductions greater than 30 %. Similar trends hold for energy costs and 

energy-related carbon emissions. 

Over all building types, states located in the warmest climates realize the greatest 

reductions in energy use from adopting the “Low Energy Case” (LEC) design because 

several of the energy efficiency improvements (e.g., overhangs and daylighting controls) 

are more beneficial for warmer climates. However, states in colder climates see greater 

percentage reductions in energy costs and carbon emissions per percentage reduction in 

energy use because the energy efficiency measures tend to shift some energy use from 

electricity to natural gas consumption. Electricity is more expensive per unit of energy 

and typically has greater carbon dioxide equivalent (CO2e) emissions per unit of energy 

relative to natural gas. Therefore the shift of energy consumption from electricity to 

natural gas can lead to greater reductions in energy costs and energy-related carbon 

emissions than reductions in total energy use. In an extreme case, cities located in Zone 8 

realize a reduction in energy costs and carbon emissions while realizing an increase in 

total energy use. 

The results for the ASHRAE 90.1-2007 design have some similarities and some 

differences relative to the results for the LEC design. Similar to the LEC design, the 

current state energy codes are a key driver of variation in the results. The variation across 

climate zones diverges depending on the state energy code. For locations in states that 

have not adopted any state energy code or have adopted older editions of ASHRAE 90.1

(-2001), warmer climate zones realize greater percentage reductions in energy use. For 

cities located in states that have adopted ASHRAE 90.1-2004, the percentage reductions 

in energy use do not follow the same trend. Instead the percentage changes are the 
xxiii 

greatest for cities in Zone 2 followed by Zone 7 and smallest for cities in Zone 1 and 

Zone 3. 

Similar to the LEC design results, some cities realize a shift in energy use from electricity 

to natural gas, which decreases energy costs and carbon emissions by a greater 

percentage than the percentage decrease in energy consumption. However, when 

averaged across all cities in a climate zone, nearly all zones realize smaller percentage 

reductions in carbon emissions than the percentage reductions in energy use because 

adopting ASHRAE 90.1-2007 decreases consumption of both electricity and natural gas 

for most cities.

The length of the study period impacts life-cycle cost-effectiveness to some degree. 

Assuming nationwide adoption of the LEC design, a 10-year study period realizes 

average life-cycle cost decreases of 1.1 % for all building types and locations. The 

percentage decrease in life-cycle costs is 1.4 % for a 20-year, 1.8 % for a 30-year, and 

1.9 % for a 40-year study period. As the study period length increases from 5 years to 40 

years, life-cycle cost-effectiveness tends to increase for more energy efficient commercial 

building designs. 

By combining the amount of new floor area in a state with its average impacts, it is 

possible to estimate the magnitude of the impacts that nationwide adoption of a given 

building design would have at the state and national levels. States with the most newly 

constructed commercial building floor area tend to realize the greatest total energy use, 

energy cost, energy-related carbon emissions, and life-cycle cost reductions from 

adopting the ASHRAE 90.1-2007 and LEC design even if those states do not realize the 

greatest percentage reductions. California, Florida, and Texas realize the greatest 

reductions in energy use (>1900 GWh) from adopting the LEC design. In comparison, 

states with the smallest amount of new floor area (Alaska, Delaware, Montana, Rhode 

Island, Vermont, and Wyoming) realize savings of less than 100 GWh from adopting the 

LEC design. For the 19 states that have not yet adopted the ASHRAE 90.1-2007 design, 

Arizona realizes the greatest reductions in energy use (946 GWh) from doing so, while 

states with the smallest amount of new floor area (Alaska, Hawaii, Maine, North Dakota, 

South Dakota, and Wyoming) realize savings of less than 106 GWh. Similar trends occur 

for total energy cost reductions and energy-related carbon emissions savings. 

The nationwide adoption of more efficient energy codes decreases total life-cycle costs. 

Adopting the LEC design decreases total life-cycle costs for 48 of 50 states for a 10-year 

study period, with Florida ($151.3 million), California ($124.9 million), and Texas 

($106.8 million) realizing the greatest life-cycle cost savings. The two states that realize 

an increase in life-cycle costs are Oregon ($0.4 million) and Washington ($11.5 million). 

For a 10-year study period, adopting the ASHRAE 90.1-2007 design reduces total 

life-cycle costs for 17 of 19 states, including 8 of 10 that have adopted ASHRAE 
xxiv 

90.1-2001 or have not yet adopted a state energy code for commercial buildings. The 

greatest life-cycle cost savings are realized by Colorado ($53.9 million), Arizona 

($30.8 million), and Alabama ($25.7 million). The two states that realize an increase in 

total life-cycle costs are Kansas ($2.9 million) and Oklahoma ($5.7 million). 

The state-level impacts are aggregated to determine the total impact of nationwide 

adoption of both the ASHRAE 90.1-2007 and LEC designs. Nationwide adoption of the 

LEC design leads to reductions totaling 34.4 TWh in energy consumption, $2.8 billion in 

energy costs, 26.3 million metric tons in energy-related carbon emissions, and 

$1.0 billion in life-cycle costs for a 10-year study period. Nationwide adoption of the 

ASHRAE 90.1-2007 design leads to reductions totaling 4.9 TWh in energy consumption, 

$312 million in energy costs, 3.8 million metric tons in energy-related carbon emissions, 

and $173 million in life-cycle costs for a 10-year study period. An increase in the study 

period length increases the total savings for all four impacts because as the length of the 

study period increases, energy cost savings become a greater fraction of total life-cycle 

cost savings.

In general, the states that realize the greatest total reductions in energy use also realize the 

greatest reductions in energy costs and energy-related carbon emissions. However, states 

with higher average electricity prices and electricity emissions rates, and states that 

realize a greater shift of fuel consumption from electricity to natural gas, realize greater 

reductions in energy costs and carbon emissions holding energy use savings constant. 

The changes per unit of floor area vary across Census regions, with the same trends 

holding for adoption of both the ASHRAE 90.1-2007 and LEC designs. The Northeast 

realizes the greatest energy cost savings per unit energy use savings due to its higher 

average higher electricity price. The Midwest realizes the greatest carbon emissions 

savings per unit of energy use savings because its average electricity emissions rate is 

much higher than that of the other Census regions. The West realizes the greatest lifecycle cost savings per unit of floor area, which is a result of a number of factors, 

including the baseline energy codes for the cities located in the Census region, the 

regional average electricity price, average energy use savings, and local construction 

costs. 

The incremental impacts in a state from adopting each newer edition of ASHRAE 90.1

lead to some interesting conclusions. For the nine states that have no state energy code, 

adoption of ASHRAE 90.1-2001 would lead to minimal energy use reductions 

(16 kWh/m2

) while significantly increasing total life-cycle costs ($15.39/m2).1The reason 

for this result is that the primary changes in the standard from ASHRAE 90.1-1999 to

 

1

 Excludes Arizona because three of the six cities in the BIRDS database have adopted ASHRAE 90.1-2004

as their local energy code. 
xxv

ASHRAE 90.1-2001 target the required efficiencies of HVAC equipment. The additional 

first costs of increasing the efficiency of HVAC equipment appear to be greater than the 

energy cost savings realized over the 10-year study period.

The adoption of ASHRAE 90.1-2004 leads to significant incremental average reductions 

in energy use (112 kWh/m2) while significantly decreasing total life-cycle costs 

($15.52/m2) relative to adopting ASHRAE 90.1-2001, and entirely offsets the incremental 

increase in life-cycle costs from adopting ASHRAE 90.1-2001 for five of the nine states 

with no state energy code. One state, Alaska, realizes an increase in energy use relative to 

ASHRAE 90.1-2001, which is a result of building requirements being relaxed for some 

cities due to the climate zone consolidation from ASHRAE 90.1-2001 to ASHRAE 

90.1-2004.

The adoption of ASHRAE 90.1-2007 leads to significantly smaller average incremental 

reductions in energy use (71 kWh/m2

) and life-cycle costs ($3.04/m2) relative to adopting 

ASHRAE 90.1-2004. Two of the nineteen states (Arkansas and Oklahoma) realize an 

increase in life-cycle costs relative to ASHRAE 90.1-2004. 

The adoption of the LEC design leads to the greatest incremental impacts on total energy 

use (202 kWh/m2

), and similar incremental impacts on life-cycle costs ($4.24/m2) as 

ASHRAE 90.1-2007 for the nineteen states that have not yet adopted ASHRAE 90.1-2007. 

Only one of the nineteen states (West Virginia) realizes an increase in life-cycle costs 

relative to ASHRAE 90.1-2007.

This study is limited in scope and would be strengthened by including sensitivity 

analysis, expanding the BIRDS database, and enabling public access to all the results. 

The environmental assessment in the BIRDS database is currently being expanded 

beyond energy-related carbon emissions to cover building materials and a full range of 

cradle-to-grave life-cycle environmental impacts. Additional energy efficiency measures, 

fuel types, discount rates, and building types would also expand the scope of the 

database. Also, given that new buildings account for a small fraction of the entire 

building stock, incorporating analysis of energy retrofits to these same prototype 

buildings would increase the coverage of the database. 

The extensive BIRDS database can be used to answer many more questions than posed in 

this report, and will be made available to the public through a simple-to-use software tool 

that allows others access to the database for their own research on building energy 

efficiency and sustainability. These improvements are underway, with comprehensive 

sustainability assessment and more detailed reporting and release of the BIRDS software 

scheduled for September 2013.
xxvi 
1

1 Introduction 

1.1 Background 

Energy efficiency requirements in current energy codes for commercial buildings vary 

across states, and many states have not yet adopted the latest energy efficiency standard 

editions. As of December 2011, state energy code adoptions range across editions of the 

American Society of Heating, Refrigerating and Air-Conditioning Engineers Energy 

Standard for Buildings Except Low-Rise Residential Buildings (ASHRAE 

90.1-2001, -2004, and -2007). ASHRAE Standard 90.1 is the industry consensus standard 

to establish the minimum energy-efficient requirements of buildings, other than low-rise 

residential buildings. Some states do not have a code requirement for energy efficiency, 

leaving it up to the locality or jurisdiction to set its own requirement. There may be 

significant energy and cost savings to be realized by states if they were to adopt more 

energy efficient commercial building energy standard editions.

1.2 Literature Review 

Pacific Northwest National Laboratory (2009) estimates the impacts for each state of 

adopting the most recent edition of the ASHRAE 90.1 Standard as of 2009, ASHRAE 

90.1-2007, as the commercial building energy code relative to the state’s current energy 

code. For states without a state commercial building energy code, the baseline is 

assumed to be ASHRAE 90.1-1999 because it is considered to represent common practice 

in the industry. The annual energy use savings and energy cost savings are estimated for 

three Department of Energy (DOE) benchmark buildings -- a medium-sized office 

building, a non-refrigerated warehouse, and a mid-rise apartment building -- to represent 

non-residential, semi-heated, and residential uses, respectively. The buildings are 

simulated in the EnergyPlus whole building energy software (DOE, 2009a) for 97 cities 

located across the U.S., ensuring that each climate zone in each state is represented. The 

study reports annual electricity and natural gas consumption per square foot of floor area 

for the buildings, assuming they are built to meet both the state’s current code and 

ASHRAE 90.1-2007. Based on these results, the percentage savings in energy and energy 

costs are calculated for the three building types for each state. The study does not 

compare energy use and energy costs across states. Life-cycle costs and carbon emissions 

are not considered in the study. 

Kneifel (2010) creates a framework to simultaneously analyze the impacts of improving 

energy efficiency on energy use, energy costs, life-cycle costs, and carbon emissions 

through an integrated design context for new commercial buildings. The paper compares 

the savings of constructing 11 prototype commercial buildings to meet the building 

envelope requirements of ASHRAE 90.1-2007 and a “Low Energy Case,” relative to 

ASHRAE 90.1-2004, for 16 cities in different climate zones across the contiguous United 
2

States. The paper finds minimal improvements in energy efficiency from building to meet 

ASHRAE 90.1-2007 relative to ASHRAE 90.1-2004 while significant savings is found by 

building to meet the “Low Energy Case.” The “Low Energy Case” is often cost-effective 

on a first cost basis and is always cost-effective over the longer study period lengths. 

Kneifel (2011a) expands on the framework and analysis in Kneifel (2010) by analyzing 

the impact of adopting the building envelope requirements of ASHRAE 90.1-2007 and a 

“Low Energy Case” relative to ASHRAE 90.1-2004 in terms of energy use, energy costs, 

energy-related carbon emissions, and life-cycle costs for 228 cities across the U.S. with at 

least one city in each state. Analysis includes 4 study period lengths (1, 10, 25, and 40 

years). The paper finds that, on average, the more energy efficient building designs are 

cost-effective. However, there is significant variation across states in terms of energy use 

savings and life-cycle cost-effectiveness driven by both climate and construction costs. 

There is also significant variation across cities within a state, even cities located within 

the same climate zone. These variations are a result of differences in local material and 

labor costs as well as energy costs. 

Kneifel (2013) analyzes 12 540 whole-building energy simulations in the Building 

Industry Reporting and Design for Sustainability (BIRDS) database covering 11 building 

types in 228 cities across all U.S. states for 9 study period lengths (1, 5, 10, 15, 20, 25, 

30, 35, and 40 years). Current state energy code performance is compared to the 

performance of alternative ASHRAE 90.1 Standard editions to determine whether more 

stringent energy standard editions are cost-effective in reducing energy consumption and 

energy-related carbon emissions. This analysis includes a “Low Energy Case” (LEC) 

building design based on ASHRAE 189.1-2009, which increases energy efficiency beyond 

the ASHRAE 90.1-2007 design. Results are analyzed in detail for the ASHRAE 90.1-2007

and LEC designs. Results are aggregated at the state level for seven states, Alaska, 

Colorado, Florida, Maryland, Oregon, Tennessee, and Wisconsin, to estimate the 

magnitude of total energy use savings, energy cost savings, life-cycle cost savings and 

energy-related carbon emissions reductions that could be attained by adoption of a more 

stringent state energy code for commercial buildings. 

Kneifel (2013b), Kneifel (2013c), Kneifel (2013d), and Kneifel (2013e) implement the 

analysis approach developed in Kneifel (2013a) for an individual state and analyze each 

state in the Northeast, Midwest, South, and West Census Regions, respectively. The 

results for each state, both on a percentage and aggregate basis, are compared across the 

Census Region to determine the driving factors for variation across states in the relative 

impacts of adopting more stringent state energy codes. The results are aggregated to the 

Census Region level to estimate the total region-wide impacts. 
3

1.3 Purpose 

The purpose of this study is to analyze the results from the BIRDS database reported in 

Kneifel (2013a, 2013b, 2013c, 2013d, 2013e), and summarize the results into the key 

nationwide trends and important interpretations for energy efficiency in new commercial 

buildings. The performance of buildings designed to meet current state energy codes is 

compared to their performance when meeting newer editions of ASHRAE 90.1

requirements to determine whether more stringent energy standard editions are 

cost-effective in reducing energy consumption and energy-related carbon emissions. Each 

state energy code is also compared to a “Low Energy Case” (LEC) building design based 

on ASHRAE 189.1-2009, which increases energy efficiency beyond the ASHRAE 

90.1-2007 design. The estimated savings for each of the building types are aggregated 

using new commercial building construction data to calculate the magnitude of the 

incremental savings that the nation may realize if its states were to adopt more energy 

efficient standard editions.

1.4 Approach 

This study uses the Building Industry Reporting and Design for Sustainability (BIRDS) 

database to analyze the benefits and costs of increasing building energy efficiency across 

the United States. BIRDS is a compilation of whole building energy simulations, building 

construction cost data, maintenance, repair, and replacement rates and costs, and energyrelated carbon emissions data for 11 building types in 228 cities across all U.S. states. 

The analysis compares energy performance of buildings designed to each state’s current 

energy code for commercial buildings to the performance of more energy efficient 

building designs to determine the energy use savings, energy cost savings, and 

energy-related carbon emissions reductions, and the associated life-cycle costs, resulting 

from adopting stricter standards as the state’s energy code. 

Results are analyzed both in percentage and total value terms. The percentage savings 

results allow for direct comparisons across energy standard editions, building types, study 

period lengths, climate zones, and cities both within each state and across the nation. 

Results are aggregated to the state and national levels to estimate the magnitude of total 

energy use savings, energy cost savings, and energy-related carbon emissions reductions 

that could be attained by adoption of more stringent energy codes, and the associated 

total life-cycle costs.

Results are summarized using both tables and figures. In cases where the material being 

discussed is of secondary importance, the associated table or figure is placed in the 

Appendices. The order in which tables and figures appear in the Appendices corresponds 

to the order in which they are cited in the text.
4
5

2 Study Design 

The BIRDS database used in this study was built following the framework developed in 

Kneifel (2010) and further expanded in Kneifel (2011a) and Kneifel (2013). This study 

analyzes whole building energy simulations, life-cycle costs, and energy-related carbon 

emissions for 5 energy efficiency designs for 11 building types, 228 cities across all fifty 

states, and 9 study period lengths.2

2.1 Building Types 

The building characteristics in Table 2-1 describe the 11 building types used in this study, 

which include 2 dormitories, 2 apartment buildings, a hotel, 3 office buildings, a school, a 

retail store, and a restaurant. The building types were selected based on a combination of 

factors, including fraction of building stock represented, variation in building 

characteristics, and ease of simulation design. These building types represent 46 % of the 

existing U.S. commercial building stock floor space.3

The prototype buildings range in 

size from 465 m2

(5000 ft2) to 41 806 m

2

(450 000 ft2). The building abbreviations 

defined in Table 2-1 are used to represent the building types in tables throughout this 

study. 

Table 2-1 Building Characteristics 

Building Type Bldg. Abbr. Floors

Floor 

Height

m (ft)

Wall Roof† Pct. 

Glazing

Building Size

m

2

(ft2)

Occupancy 

Type

U.S. Floor 

Space (%)

Dormitory DORMI04 4 3.66 (12) Mass IEAD 20 % 3097 (33 333) Lodging 7.1 %

Dormitory DORMI06 6 3.66 (12) Steel IEAD 20 % 7897 (85 000)

Hotel HOTEL15 15 3.05 (10) Steel IEAD 100 % 41 806 (450 000)

Apartment APART04 4 3.05 (10) Mass IEAD 12 % 2787 (30 000)

Apartment APART06 6 3.15 (10) Steel IEAD 14 % 5574 (60 000)

School, High HIGHS02 2 4.57 (15) Mass IEAD 25 % 12 077 (130 000) Education 13.8 %

Office OFFIC03 3 3.66 (12) Mass IEAD 20 % 1858 (20 000) Office 17.0 %

Office OFFIC08 8 3.66 (12) Mass IEAD 20 % 7432 (80 000)

Office OFFIC16 16 3.05 (10) Steel IEAD 100 % 24 155 (260 000)

Retail Store RETAIL1 1 4.27 (14) Mass IEAD 10 % 743 (8000) Mercantile* 6.0 %

Restaurant RSTRNT1 1 3.66 (12) Wood IEAD 30 % 465 (5000) Food Service 2.3 %

*Only includes non-mall floor area.

†IEAD = Insulation Entirely Above Deck

 

2

 See Kneifel (2011b) for additional details on the whole building energy simulations used in the BIRDS 

database. 

3

 Estimate is based on the Commercial Building Energy Consumption Survey (CBECS) database.
6

2.2 Building Designs 

Current state energy codes are based on different editions of the International Energy 

Conservation Code (IECC) or ASHRAE 90.1 Standard, which have requirements that 

vary based on a building’s characteristics and the climate zone of the building location. 

For this study, the prescriptive requirements of the ASHRAE 90.1 Standard-equivalent 

design are used to meet current state energy codes and to define the alternative building 

designs. States that have not yet adopted a state energy code are assumed to meet 

ASHRAE 90.1-1999 building energy efficiency requirements. A “Low Energy Case” 

design based on ASHRAE 189.1-2009, which goes beyond ASHRAE 90.1-2007, is 

included as an additional building design alternative. 

Table 2-2 shows that commercial building energy codes as of December 2011 vary by 

state.4

 In a few instances, local jurisdictions have adopted energy standard editions that 

are more stringent than the state energy codes.5

These cities are also included in Table 

2-2.

 

4

 Since the publication of Kneifel (2011b) and Kneifel (2012), the BIRDS database has been updated to 

include subsequent changes in state energy codes through December 2011. 

5

 Local and jurisdictional requirements are obtained from the Database of State Incentives for Renewables 

and Efficiency (DSIRE). State energy code requirements targeting only public buildings and green 

standards are ignored in this study. 
7

Table 2-2 Energy Code by State and City Exception 

Location Energy Code Location Energy Code Location Energy Code

AK None IN 2007 NV 2004

AL None KS None NY 2007

Huntsville 2001 KY 2007 OH 2007

AR 2001 LA 2007 OK None

AZ None MA 2007 OR 2007

Flagstaff 2004 MD 2007 PA 2007

Phoenix 2004 ME None RI 2007

Tucson 2004 MI 2007 SC 2004

CA* 2007 MN 2004 SD None

CO 2001 MO None Huron 2001

Grand Junction 2004 St Louis 2001 TN 2004

CT 2007 MS None TX 2007

DE 2007 MT 2007 UT 2007

FL 2007 NC 2007 VA 2007

GA 2007 ND None VT 2007

HI 2004 NE 2007 WA 2007

IA 2007 NH 2007 WI 2007

ID 2007 NJ 2007 WV 2001

IL 2007 NM 2007 WY None

Note: Some city ordinances require energy codes that exceed state energy codes.

Note: State codes as of December 1, 2011.

Note: ASHRAE 90.1-2007 is the building design that best matches Title 24 requirements. 

State energy codes vary from ASHRAE 90.1-1999 to ASHRAE 90.1-2007 with some 

regional trends shown in Figure 2-1. The states in the central U.S. tend to wait longer to 

adopt newer ASHRAE 90.1 Standard editions. However, there are many cases in which 

energy codes of neighboring states vary drastically. For example, Missouri has no state 

energy code while of the 8 surrounding states, 2 have no state energy code, 1 has adopted 

ASHRAE 90.1-2001, 1 has adopted ASHRAE 90.1-2004, and 4 have adopted ASHRAE 

90.1-2007.
8

Figure 2-1 State Commercial Energy Codes6

The 228 cities and ASHRAE climate zones for the U.S. are seen in Figure 2-2. These 

cities are selected for three reasons. First, the cities are spread out to represent the entire 

United States, and represent as many climate zones as possible in each state. Second, the 

locations include all the major population centers in the country. Third, multiple locations 

for a climate zone within a state are included to allow building costs to vary for each 

building design. 

 

6

 Figure was obtained from the DOE Building Technologies Program in December 2011. 
9

Figure 2-2 Cities and ASHRAE Climate Zones 

2.3 Study Period Lengths 

Nine study period lengths are chosen for this analysis: 1 year, 5 years, 10 years, 15 years, 

20 years, 25 years, 30 years, 35 years, and 40 years. The wide variation in investment 

time horizons allows this report to analyze the impact the study period length has on the 

benefits and costs of more stringent state energy code adoption. A 1-year study period is 

more representative of a developer that intends to sell a property soon after it is 

constructed. A 5-year to 15-year study period more closely represents a building owner’s 

time horizon because few owners are concerned about costs realized beyond a decade 

into the future. The 20-year to 40-year study periods better represents institutions, such as 

colleges or government agencies, because these entities will own or lease buildings for 

20 or more years. Most of the analysis in this study uses a 10-year study period. 
10
11

3 Cost Data 

The cost data collected to estimate life-cycle costs for the BIRDS database originates 

from multiple sources, including RS Means databases (RS Means, 2009), Whitestone 

(2008), and the U.S. Energy Information Administration (EIA) (EIA, 2010).7 Costs are 

grouped into two categories, first costs that include initial building construction costs and 

future costs that include operational costs, maintenance, repair, and replacement costs, 

and building residual value. Both of these cost categories are described below. 

3.1 First Costs 

Building construction costs are obtained from the RS Means CostWorks online databases 

(RS Means, 2009). The costs of a prototypical building are estimated by the RS Means 

CostWorks Square Foot Estimator to obtain the default costs of each component within 

each separate building building type. The RS Means default building is the baseline used 

to create a building that is compliant with each of the five energy efficiency design 

alternatives: ASHRAE 90.1-1999, ASHRAE 90.1-2001, ASHRAE 90.1-2004, ASHRAE 

90.1-2007, and the higher efficiency “Low Energy Case” (LEC) design. The RS Means 

default buildings are adapted to match the five prototype building designs by using the 

RS Means CostWorks Cost Books databases. 

Five components -- roof insulation, wall insulation, windows, lighting, and HVAC 

efficiency -- are changed to make the prototypical designs ASHRAE 

90.1-1999, -2001, -2004, and -2007 compliant. A summary of the minimum requirement 

ranges, excluding HVAC efficiency, for each building design are shown in Table 3-1. 

The windows are selected to meet the minimum window characteristics (U-factor, solar 

heat gain coefficient (SHGC), and visible transmittance (VT)) required by the building 

design at the lowest possible cost. The lighting density in watts per unit of conditioned 

floor area is adjusted to meet each standard edition’s requirements. 

 

7

 See Kneifel (2012) for additional details of the cost data used in the BIRDS database. 
12

Table 3-1 Energy Efficiency Component Requirements for Alternative Building 

Designs 

Design 

Component Parameter Units

ASHRAE

90.1-1999

ASHRAE

90.1-2001

ASHRAE

90.1-2004

ASHRAE

90.1-2007

Low Energy

Case*

Roof 

Insulation R-Value m

2

∙K/W 

(ft2∙°F∙h/Btu)

1.7 to 4.4

(10.0 to 25.0)

1.7 to 4.4

(10.0 to 25.0)

2.6 to 3.5

(15.0 to 20.0)

2.6 to 3.5

(15.0 to 20.0)

4.4 to 6.2

(25.0 to 35.0)

Wall 

Insulation R-Value m

2

*K/W 

(ft2∙°F∙h/Btu)

0.0 to 3.8

(0.0 to 21.6)

0.0 to 3.8

(0.0 to 21.6)

0.0 to 2.7

(0.0 to 15.2)

0.0 to 2.7

(0.0 to 15.2)

0.7 to 5.5

(3.8 to 31.3)

Windows U-Factor W/(m2∙K) 

(Btu/(h∙ft2∙°F))

1.42 to 7.21

(0.25 to 1.27)

1.42 to 7.21

(0.25 to 1.27)

1.99 to 6.47

(0.35 to 1.14)

2.50 to 6.47

(0.44 to 1.14)

1.97 to 6.42

(0.35 to 1.13)

SHGC Fraction 0.14 to NR† 0.14 to NR† 0.17 to NR† 0.25 to NR 0.25 to 0.47

Lighting Power 

Density W/m2

(W/ft2)

14.0 to 20.5

(1.3 to 1.9)

14.0 to 20.5

(1.3 to 1.9)

10.8 to 16.1

(1.0 to 1.5)

10.8 to 16.1

(1.0 to 1.5)

8.6 to 16.1

(0.8 to 1.5)

Overhangs None None None None Zones 1 to 5

Daylighting None None None None Zones 1 to 8

†North facing SHGC requirements are less restrictive than the requirements for the other 3 orientations.

* Low Energy Case design requirements are taken from the EnergyPlus simulations, and are based on ASHRAE 189.1-2009.

NR = No Requirement for one or more climate zones. By definition, the value of SHGC cannot exceed 1.0.

The LEC design increases the thermal efficiency of insulation and windows beyond 

ASHRAE 90.1-2007, further reduces the lighting power density, and adds daylighting and 

window overhangs. The lighting density of the lighting system is decreased by first 

increasing the efficiency of the lighting system and then decreasing the number of 

fixtures in the lighting system.8 Daylighting is included for all building types and climate 

zones. Overhangs are placed on the east, west, and south sides of the building for each 

floor in Climate Zone 1 through Climate Zone 5 because these warmer climates are the 

zones that benefit from blocking solar radiation.9

Since the design of the BIRDS database, ASHRAE 90.1-2010 has been finalized and 

published. Table 3-2 gives a perspective of how the ASHRAE 90.1-2007 and LEC designs 

compare to ASHRAE 90.1-2010. In general, the requirements for ASHRAE 90.1-2010 are 

stricter than ASHRAE 90.1-2007 and less strict than the LEC design. The key exception is 

the lighting power density requirements for mid-rise and high-rise residential buildings,

and wall insulation requirements for steel-framed mid-rise and high-rise residential 

buildings, where the requirements for ASHRAE 90.1-2010 are more stringent than for the 

LEC design. 

 

8

 First, incandescent lighting is replaced with compact fluorescent lighting while typical T-12 fluorescent 

tube lighting is replaced with more efficient T-8 fluorescent tube lighting to decrease the lighting density of 

the lighting system. Second, the number of fixtures is reduced to meet the remainder of the required 

reduction in watts per unit of floor area. Increasing the efficiency of the lighting increases the costs of 

construction. The first approach increases first costs while the second approach decreases first costs for the 

lighting system. This approach is based on Belzer et al. (2005) and Halverson et al. (2006). 

9

 Overhang cost source is Winiarski et al. (2003) 
13

Table 3-2 Energy Efficiency Component Requirements for the ASHRAE 90.1-2007, 

ASHRAE 90.1-2010, and LEC Designs 

Design Component Parameter Units

ASHRAE

90.1-2007

ASHRAE

90.1-2010

Low Energy

Case*

Roof Insulation R-Value m

2

∙K/W 

(ft2∙°F∙h/Btu)

2.6 to 3.5

(15.0 to 20.0)

2.6 to 3.5

(15.0 to 20.0)

4.4 to 6.2

(25.0 to 35.0)

Wall Insulation R-Value m

2

*K/W 

(ft2∙°F∙h/Btu)

0.0 to 2.7

(0.0 to 15.2)

0.0 to 2.7

(0.0 to 25.0)

0.7 to 5.5

(3.8 to 31.3)

Windows U-Factor W/(m2∙K) 

(Btu/(h∙ft2∙°F))

2.50 to 6.47

(0.44 to 1.14)

1.99 to 6.47

(0.35 to 1.2)

1.97 to 6.42

(0.35 to 1.13)

SHGC Fraction 0.25 to NR 0.25 to NR† 0.25 to 0.47

Lighting Power Density W/m2(W/ft2)

10.8 to 16.1

(1.0 to 1.5)

6.5 to 15.1

(0.6 to 1.4)

8.6 to 16.1

(0.8 to 1.5)

Overhangs None None Zones 1 to 5

Daylighting None Zones 1 to 8 Zones 1 to 8

* Low Energy Case design requirements are taken from the EnergyPlus simulations, and are based on ASHRAE 189.1-2009.

NR = No Requirement for one or more climate zones. By definition, the value of SHGC cannot exceed 1.0.

Table 3-3 summarizes the HVAC efficiency requirements for each building design option 

across the different types of HVAC equipment.10 Note that the LEC design assumes the 

same efficiency as ASHRAE 90.1-2007. This study assumes that cooling equipment is run 

on electricity while heating equipment is run on natural gas. The most significant 

increases in HVAC efficiency requirements occur between ASHRAE 90.1-1999 and 

ASHRAE 90.1-2001 except for rooftop packaged units, which have consistently 

increasing requirements across multiple ASHRAE 90.1 Standard editions.

Table 3-3 HVAC Energy Efficiency Requirements for Alternative Building Designs

HVAC 

Type

Equipment Type Unit ASHRAE 

90.1-1999

ASHRAE 

90.1-2001

ASHRAE 

90.1-2004

ASHRAE 

90.1-2007

Low Energy 

Case

Cooling Rooftop Packaged Unit EER 8.2 to 9.0 9.0 to 9.9 9.2 to 10.1 9.5 to 13.0 9.5 to 13.0

Air-Cooled Chiller COP 2.5 to 2.7 2.8 2.8 2.8 2.8

Water-Cooled Chiller COP 3.80 to 5.20 4.45 to 5.50 4.45 to 5.50 4.45 to 5.50 4.45 to 5.50

Split System with 

Condensing Unit

EER 8.7 to 9.9 9.9 to 10.1 10.1 10.1 10.1

Heating Hot Water Boiler Et 75% to 80% 75% to 80% 75% to 80% 75% to 80% 75% to 80%

Furnace Et 80% 75% to 80% 75% to 80% 75% to 80% 75% to 80%

Assume that 80 %Ec = 75% Et and AFUE = Et, where Ec = combustion efficiency; Et = thermal efficiency; AFUE = Annual Fuel 

Utilization Efficiency

EER = Energy Efficiency Ratio

COP = Coefficient of Performance

Note: Efficiency requirement ranges are based on the system sizes calculated in the whole building energy simulations.

 

10 This study does not account for new HVAC efficiency requirements set by federal regulations. 
14

The HVAC system size varies across the five building designs because changing the 

thermal characteristics of the building envelope alters the heating and cooling loads of the 

building. The EnergyPlus whole building energy simulations “autosize” the HVAC 

system to determine the appropriate system size to efficiently maintain the thermal 

comfort while dealing with ventilation requirements. For each building design, the 

HVAC cost for the default HVAC system is replaced with the cost of the “autosized”

HVAC system. An HVAC efficiency cost multiplier is used to adjust the HVAC costs in 

accordance with the standard efficiency requirements shown in Table 3-3. 

Construction costs for a building in each location are estimated by summing the baseline 

costs for the RS Means default building and the changes in costs required to meet the 

alternative prototype designs. National average construction costs are adjusted with the 

2009 RS Means CostWorks City Indexes to control for local material and labor price 

variations. The “weighted average” city construction cost index is used to adjust the costs 

for the baseline default building while “component” city indexes are used to adjust the 

costs for the design changes. Once the indexed construction cost of the building is 

calculated, it is multiplied by the contractor “mark-up” rate, 25 %, and architectural fees 

rate, 7 %, to estimate the building's “first costs” of construction for the prototype 

buildings. These rates are the default values used by the RSMeans Square Foot 

Estimator.

3.2 Future Costs 

Component and building lifetimes and component repair requirements are based on data 

from Whitestone (2008). Building service lifetimes are assumed constant across climate 

zones: apartment buildings lasting for 65 years; dormitories for 44 years; and hotels, 

schools, office buildings, retail stores, and restaurants for 41 years. 

Building component maintenance, repair, and replacement (MRR) rates are from Kneifel 

(2010) and Kneifel (2011a). Insulation and windows are assumed to have a lifespan 

greater than 40 years and have no maintenance requirements. Insulation is assumed to 

have no repair costs. Windows have an assumed annual repair cost equal to replacing 1 % 

of all window panes, with costs that vary depending on the required window 

specifications (RS Means, 2009). The heating and cooling units have different lifespans 

and repair rates based on climate, ranging from 4 years to 33 years for repairs and 13 

years to 50 years for replacements. 

MRR cost data are collected from two sources. The total maintenance and repair costs per 

square foot of conditioned floor area (minus the HVAC maintenance and repair costs) 

represent the baseline MRR costs per unit of floor area, which occur for a building type 

regardless of the energy efficiency measures incorporated into the design. These data are 

collected from Whitestone (2008), which reports average maintenance and repair costs 
15

per unit of floor area by building component for each year of service life for each 

building type. The building types in Whitestone do not match exactly to the 11 building 

types selected for this study, so the most comparable profile is selected. 

RS Means CostWorks is the source of MRR costs for the individual components for 

which MRR costs change across alternative building designs, which in this analysis are 

the HVAC system, lighting system, and windows. Lighting systems, including 

daylighting controls for the LEC design, are assumed to be replaced every 20 years. The 

HVAC system size varies based on the thermal performance of the alternative building 

design, which results in varying MRR costs because smaller systems are relatively 

cheaper to maintain, repair, and replace. 

Future MRR costs are discounted to equivalent present values using the Single Present 

Value (SPV) factors for future non-fuel costs reported in Rushing and Lippiatt (2008), 

which are calculated using the U.S. Department of Energy's 2008 real discount rate for 

energy conservation projects (3 %). 

A building's residual value is its value at the end of the study period. It is estimated in 

three parts, for the building (excluding components replaced during the study period), the 

HVAC system, and the lighting system based on the approach defined in Fuller et al. 

(1996). The building's residual value is assumed to be equal to the building's first cost 

(minus any components replaced over the study period) multiplied by the ratio of the 

study period to the service life of the building, and discounted from the end of the study 

period. 

Two components may be replaced during the study period, the lighting and HVAC 

systems. Residual values for these components are computed for each location in a 

similar manner to the building residual value. The remaining “life” of the component is 

determined by taking its service life minus the number of years since its last installation, 

whether it occurred during building construction or replacement. The ratio of remaining 

life to service life is multiplied by the installed cost of the lighting and HVAC systems,

and discounted from the end of the study period. The lighting system service life is 20 

years while the HVAC system service life varies by location based on Towers et al.

(2008). 

Annual energy costs are estimated by multiplying annual electricity and natural gas use 

predicted by the whole building energy simulation by the average state retail commercial 

electricity and natural gas prices, respectively. Average state commercial electricity and 

natural gas prices for 2009 are collected from the Energy Information Administration 

(EIA) Electric Power Annual State Data Tables and Natural Gas Navigator, respectively.

The electricity and natural gas prices are assumed to change over time according to EIA 

forecasts from 2009 to 2039. These forecasts are embodied in the Federal Energy 
16

Management Program (FEMP) Uniform Present Value Discount Factors for energy price 

estimates (UPV*) reported in Rushing and Lippiatt (2009).11 The UPV* values are used 

to discount future energy costs to equivalent present values. The discount factors vary by 

Census region, building sector, and fuel type. 

 

11 The escalation rates for years 31 to 40 are assumed to be the same as for year 30. 
17

4 Building Stock Data 

Aggregating the savings for newly constructed commercial buildings to the state and 

national levels requires new construction data for each building type within each state. 

This study uses the commercial building weighting factors reported in Jarnagin and 

Bandyopadhyay (2010) to estimate the total energy use savings, energy cost savings, lifecycle cost savings, and carbon emissions reduction resulting from adopting newer energy 

standard editions for each state. Jarnagin and Bandyopadhyay (2010) use two databases 

to generate the commercial building weighting factors: the 2003 Commercial Buildings 

Energy Consumption Survey (CBECS) and a McGraw-Hill construction dataset. The 

databases and the resulting weighting factors are described below. 

4.1 Databases 

The Commercial Buildings Energy Consumption Survey (CBECS) is a sample survey 

that collects information on the existing stock of U.S. commercial buildings. The sample 

includes 5215 buildings across the U.S. and 14 building type categories: education, food 

sales, food service, health care, lodging, mercantile, office, public assembly, public order 

and safety, religious worship, service, warehouse and storage, other, and vacant. Each 

category includes up to 12 subcategories as shown in Table A-1 in the Appendix A. The 

survey data do not report the age or specific location of the building to protect the 

confidentiality of the respondents.

The McGraw-Hill dataset includes data for all new commercial buildings and additions, 

over 254 000 records and 761.8 million m

2

(8.2 billion ft2) of new construction, for 2003 

through 2007. The data are more detailed than the CBECS data, and includes year of 

construction and location.

4.2 Weighting Factors 

Jarnagin and Bandyopadhyay (2010) maps the more detailed McGraw-Hill dataset to the 

CBECS categories and subcategories shown in Table 4-1. The prototype commercial 

buildings analyzed in this study, shown in bold, represent 46.4 % of nationwide new 

commercial building stock square footage for 2003 through 2007. The McGraw-Hill 

dataset is aggregated at the CBECS category-level. For this study, a prototype building is 

assumed to represent its entire CBECS category, which implies the prototypes together 

represent 56.8 % of the new commercial building stock.
18

Table 4-1 New Commercial Building Construction (U.S., 2003 through 2007) 

Building Detail

Conditioned Floor 

Area

1000 m

2

(1000 ft2)

Percentage in 

Category

Percentage 

of Total

Office Large 20 451 (220 134) 22.2 % 2.6 %

Office Medium 37 170 (400 091) 40.4 % 4.8 %

Office Small 34 468 (371 009) 37.4 % 4.5 %

Retail 93 762 (1 009 246) 12.2 %

Strip Mall 34 847 (375 093) 4.5 %

School Primary 30 697 (330 418) 4.0 %

School Secondary 63 686 (685 508) 8.3 %

Hospital 21 194 (228 131) 2.8 %

Other Health Care 26 865 (289 171) 3.5 %

Restaurant Sit Down 4055 (43 650) 0.5 %

Restaurant Fast Food 3605 (38 809) 0.5 %

Hotel Large 30 432 (327 562) 0.4 %

Hotel/Motel Small 10 576 (113 837) 1.4 %

Warehouse 102 746 (1 105 951) 13.4 %

Apartment High-rise 55 114 (593 241) 55.1 % 7.2 %

Apartment Mid-rise 44 997 (484 343) 44.9 % 5.9 %

No Prototype 153 270 (1 649 785) 20.0 %

Total (2003-2007) 767 934 (8 265 977) 100.0 %

The types and floor area of buildings being constructed vary across states. Table A-2, 

Table A-3, and Table A-4 in the Appendix A report new building construction for 2003 

through 2007 by building type and state, in total square meters, total square feet, and 

percentage terms, respectively. The data in Table A-2 are used to aggregate the total 

savings for the new construction in the CBECS categories represented by the prototype 

building analyzed in this study. Nine of the eleven prototype commercial buildings 

analyzed in this study are covered by data reported in Table 4-1. No data for dormitories 

are reported, which limits the ability to estimate statewide impacts for the two types of 

dormitories. 
19

5 Analysis Approach 

The analysis in this report compares benefits and costs of the status quo state energy 

codes to more stringent alternatives. The relative changes in energy use, energy costs, 

energy-related carbon emissions, and life-cycle costs use the current energy code for a 

state as the baseline and uses each ASHRAE 90.1 Standard edition that is newer than the 

standard required by the current state energy code as an alternative design. The results are 

considered on both a percentage change and an aggregate change basis. 

5.1 Energy Use 

The analysis uses each state’s current energy code as the baseline energy efficiency 

design. For any state without a state energy code, ASHRAE 90.1-1999 is assumed to be 

the baseline because it represents minimum energy-related industry practices. The 

baseline for each state is compared to the higher energy efficiency building designs to 

determine the relative annual energy savings resulting from adopting the alternative 

standard edition as the state’s energy code. For example, if a state’s energy code has 

adopted ASHRAE 90.1-2001 as its energy standard requirement, this baseline energy use 

is compared to the energy use of all newer energy standard editions, ASHRAE 90.1-2004

and ASHRAE 90.1-2007, as well as a “Low Energy Case” that increases building energy 

efficiency beyond ASHRAE 90.1-2007. 

It is assumed that the building maintains its energy efficiency performance throughout the 

study period, resulting in energy consumption remaining constant over the entire study 

period. This assumption is reasonable given the maintenance, repair, and replacement 

costs included in the analysis to ensure the building and its equipment perform as 

expected. 

5.2 Life-Cycle Costing 

Life-cycle costing (LCC) takes into account all relevant costs throughout the chosen 

study period, including construction costs, maintenance, repair, and replacement costs, 

energy costs, and residual values. A cost’s present value (PV) is calculated by 

discounting its nominal value into today’s dollars based on the year the cost occurs and 

the assumed discount rate. LCC of buildings typically compares the costs for a baseline 

building design to the costs for alternative, more energy-efficient building designs to 

determine if future operational savings justify higher initial investments.12 For this study, 

the design based on any ASHRAE 90.1 Standard edition that is newer than the standard 

edition required by the current state energy code is compared to the baseline state energy 

code compliant design to determine the changes in life-cycle costs. 

 

12 All life-cycle cost calculations are based on ASTM Standards of Building Economics (2012).
20

Two metrics are used to analyze changes in life-cycle costs: net LCC savings and net 

LCC savings as a percentage of base case LCC. Net LCC savings is the difference 

between the base case and alternative design's LCCs. 

5.3 Carbon Assessment 

The BIRDS database expands on Kneifel (2011a) by conducting a life-cycle assessment 

(LCA) of energy-related greenhouse gas emissions, following guidance in the 

International Organization for Standardization (ISO) 14040 series of standards for LCA. 

The analysis quantifies the greenhouse gas emissions from electricity and natural gas use 

on a cradle-to-grave basis, including emissions from raw materials acquisition, materials 

processing, generation, transmission, distribution, use, and end-of-life. 

The assessment of cradle-to-grave energy-related carbon emissions considers a number of 

greenhouse gases for two types of energy consumption, electricity and natural gas. 

Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the most prevalent. 

While carbon emissions from natural gas use can be assessed on a national average basis, 

those from electricity use are highly dependent upon the fuel mixes of regional electricity 

grids. For this reason, electricity emissions are assessed at the state-level using North 

American Electric Reliability Corporation (NERC) sub-region level data.13 The life-cycle

data sets for natural gas production and combustion as well as for all fuel sources in the 

electricity grid come from the U.S. Life-Cycle Inventory (LCI) database (LCI, 2012). The 

state-level average emissions rates per GWh (MBtu) of electricity generated are obtained 

from the 2007 Emissions and Generation Resource Integrated Database (eGRID, 2007), 

which is a collection of data from the EIA, the Federal Energy Regulatory Commission 

(FERC), and the Environmental Protection Agency (EPA). 14 Table A-5 in the Appendix 

A shows variation in the emissions rates for the top three greenhouse gases by state, 

which results from differing fuel mixes used for electricity generation in a state.15

These greenhouse gas emissions are converted into a common unit of measure called 

carbon dioxide equivalents (CO2e) using equivalency factors reported in Table 5-1, which 

represent the global warming potential (GWP) of one unit of greenhouse gas relative to 

that of the same amount of carbon dioxide. For example, one unit of methane has 25 

times the GWP as the same amount of carbon dioxide, and nitrous oxide has 298 times 

the GWP as carbon dioxide. The aggregated CO2e is calculated by taking the amount of 

 

13 For states located in more than one NERC sub-region, a weighted average of emissions rates for the 

multiple sub-regions is implemented. 

14 Emissions rates are held constant over all study periods. 

15 While carbon assessment of building construction, maintenance, repair, and replacement is currently 

excluded from the analysis, it is currently under development and will be included in future versions of this 

work. 
21

each flow multiplied by its CO2e factor, and summing the resulting CO2 equivalencies. 

The results are analyzed in metric tons of CO2e emissions, and will be referred to as 

“carbon emissions” for the remainder of the report.

Table 5-1 Greenhouse Gas Global Warming Potentials 

Environmental Flow GWP (CO2e)

Carbon Dioxide (CO2) 1

Methane (CH4) 25

Nitrous Oxide (N2O) 298

Ethane, 1,1-difluoro-, HFC-152a 124

Ethane, 1,1,1-trichloro-, HCFC-140 146

Ethane, 1,1,1,2-tetrafluoro-, HFC-134a 1430

Ethane, 1,1,2-trichloro-1,2,2-trifluoro-, CFC-113 6130

Ethane, 1,2-dichloro-1,1,2,2-tetrafluoro-, CFC-114 10 000

Ethane, hexafluoro-, HFC-116 12 200

Methane, bromo-, Halon 1001 5

Methane, bromochlorodifluoro-, Halon 1211 1890

Methane, bromotrifluoro-, Halon 1301 7140

Methane, chlorodifluoro-, HCFC-22 1810

Methane, dichloro-, HCC-30 9

Methane, dichlorodifluoro-, CFC-12 10 900

Methane, monochloro-, R-40 13

Methane, tetrachloro-, CFC-10 1400

Methane, tetrafluoro-, CFC-14 7390

Methane, trichlorofluoro-, CFC-11 4750

Methane, trifluoro-, HFC-23 14 800

5.4 Analysis Metrics 

Three metrics are used to analyze the results: simple percentage changes, aggregate 

changes, and changes per unit of floor area. The average percentage energy use savings, 

energy cost savings, energy-related carbon emissions reductions, and life-cycle cost 

savings are calculated by taking the simple average of the percentage savings for each 

location-building type combination in the state or nation. The average of the percentage 

change is used instead of the average change in total values for the state or nation because 

that would in effect give greater weight to buildings or locations with greater total 

changes. The simple average approach used in this study weights each location-building 

type equally. 

The estimated change in total energy use, energy costs, energy-related carbon emissions, 

and life-cycle costs for each of the building types is combined with new commercial 

building construction data to calculate the magnitude of the available total savings a state 
22

may realize if it were to adopt a more energy efficient standard as its state energy code 

using the following equation.

(1) 

∑ 

 

 

∑ 

 

 

Where Ij = total change for state j

CFAi = average annual newly constructed floor area for building type i for state j

Ri = average change per unit of floor area for building type i for state j

Fi = fraction of average annual new floor area represented by building type i for 

state j

For each building type i, the average change per unit of floor area for all cities in a state 

(Ri) is multiplied by the average annual floor area of new construction for 2003 to 2007 

for building type i in that state (CFAi) to estimate the total savings for that building type 

for that state. The impacts are summed across all eleven building prototypes. These 

impacts are then divided by the amount of average annual new commercial floor area 

represented by the eleven building prototypes (F), which scale the results to the statewide 

impacts of all new commercial construction (Ij). Using this approach to estimate the total 

impacts for a state requires the assumption that the savings realized by the BIRDS 

building prototypes are representative of new commercial building construction as a 

whole. 

The national-level impacts (IT) are estimated using Equation 2, where the impacts for 

state j estimated using Equation 1 (Ij) are summed across all fifty states. 

(2) ∑ 

 

 

Where IT = nationwide total impacts 

Ij = total impacts in state j

The third metric, change per unit of floor area, allows for comparisons across states to 

determine which states realize the greatest impacts per unit of construction. Equation 3 

shows this calculation, where the total statewide impacts estimated in Equation 1 (Ij) are 

divided by the total average annual new floor area for all building types in a state 

(TCFAj), creating a metaphorical “bang-for-your-buck” comparison across states.

(3) 

 

 

Where AVGIj = average impact per unit of new floor area in state j

Ij = total impacts in state j

TCFAj = total average annual new floor area for all building types in state j 
23

It is necessary to assume a particular study period length to generate results. Although the 

annual energy use savings and energy-related carbon emissions reductions, both in 

percentage and total value terms, are assumed to be the same across study period lengths, 

the energy costs and life-cycle costs vary with the study period length because costs vary 

year-over-year. A 10-year study period is used for the majority of this analysis because it 

is the most realistic investor time frame of the 9 study period length options.

5.5 Regression Analysis 

Determining the influence of some factors considered in this study requires a more 

statistically rigorous approach: regression analysis. Regression analysis is used to 

estimate the correlation between characteristics of a location and the impact the location 

realizes from adopting a more stringent energy code. This study applies an Ordinary 

Least Squares (OLS) model with dummy variables, also referred to as a Least Squares 

Dummy Variable (LSDV) Model, for the regression analysis. 
24
25

6 Nationwide Impacts of Adopting Low Energy Case Design 

This section analyzes benefits from nationwide adoption of the LEC design relative to the 

current collection of state energy codes. Benefits are evaluated across several dimensions: 

time, building type, geography (climate zone and state), and energy code. There are three 

metrics implemented to analyze the results: percentage changes, total changes, and 

changes per unit of floor area. Regression analysis is used to statistically estimate the 

drivers of variation in impacts across cities within the same state. 

6.1 Percentage Changes 

Average percentage change impacts from adopting the LEC design are estimated for 

energy use, energy costs, carbon emissions, and life-cycle costs. Impacts are evaluated 

across four dimensions: study period length, building type, climate zone, and state energy 

code. 

6.1.1 Results by Study Period Length 

It is important to consider how the study period length – representing the time horizon of 

the investor -- impacts energy use, energy costs, energy-related carbon emissions, and 

life-cycle costs. Nine study period lengths are analyzed: 1 year, 5 years, 10 years, 15 

years, 20 years, 25 years, 30 years, 35 years, and 40 years. 

The average reduction in energy use from adoption of the LEC design is constant over all 

study period lengths because energy efficiency is assumed to be constant over time. Table 

6-1 shows that the national average reduction in energy use across all cities in the study 

ranges from -10.6 % to -30.7 %, depending on the building type, with an overall national 

average of -17.8 %. 

Table 6-1 Nationwide Average Percentage Change in Energy Use from Adoption of 

the LEC Design by Building Type 

Building 

Type

Percentage 

Change

APART04 -14.8

APART06 -15.6

DORMI04 -16.9

DORMI06 -15.2

HOTEL15 -13.9

HIGHS02 -10.6

OFFIC03 -23.0

OFFIC08 -21.5

OFFIC16 -15.3

RETAIL1 -18.9

RSTRNT1 -30.7

Average -17.8
26

As shown in Table 6-2, reductions in energy costs vary slightly, in percentage terms, over 

increasing study period lengths. The national average reduction in energy costs across all 

location-building type combinations changes from -22.8 % for a 1-year study period 

to -22.3 % for a 40-year study period. The minor variation is a result of the escalation 

rates used to adjust future energy prices, which vary by Census Region. The national 

average reduction ranges from -17.4 % to -35.6 %, depending on the building type and 

study period. 

Table 6-2 Nationwide Average Percentage Change in Energy Costs from Adoption 

of the LEC Design by Building Type and Study Period Length 

Building 

Type

Study Period Length

1 5 10 15 20 25 30 35 40

APART04 -21.5 -21.3 -21.2 -21.1 -21.0 -21.0 -20.9 -20.8 -20.7

APART06 -23.2 -23.0 -22.9 -22.8 -22.7 -22.6 -22.5 -22.4 -22.4

DORMI04 -22.4 -22.3 -22.2 -22.1 -22.1 -22.0 -21.9 -21.9 -21.8

DORMI06 -22.7 -22.5 -22.4 -22.3 -22.2 -22.1 -22.0 -22.0 -21.9

HOTEL15 -19.8 -19.6 -19.6 -19.5 -19.4 -19.3 -19.3 -19.2 -19.2

HIGHS02 -18.3 -18.1 -18.0 -17.9 -17.8 -17.7 -17.6 -17.5 -17.4

OFFIC03 -25.3 -25.2 -25.2 -25.2 -25.2 -25.2 -25.1 -25.1 -25.1

OFFIC08 -22.8 -22.8 -22.8 -22.8 -22.8 -22.8 -22.7 -22.7 -22.7

OFFIC16 -18.4 -18.4 -18.3 -18.3 -18.3 -18.2 -18.2 -18.2 -18.1

RETAIL1 -20.9 -20.9 -20.9 -20.9 -20.8 -20.8 -20.8 -20.8 -20.8

RSTRNT1 -35.6 -35.5 -35.4 -35.3 -35.3 -35.2 -35.2 -35.1 -35.1

Average -22.8 -22.7 -22.6 -22.6 -22.5 -22.5 -22.4 -22.3 -22.3

Since the national average reduction in energy use across all location-building type 

combinations is constant over all study periods, the average energy-related carbon 

emissions are also assumed constant at -22.9 %.16 The national average reduction in 

carbon emissions ranges from -18.5 % to -35.6 % depending on the building type, as 

shown in Table 6-3. 

 

16 Electricity fuel mixes are assumed to be fixed over all study periods. 
27

Table 6-3 Nationwide Average Percentage Change in Carbon Emissions from 

Adoption of the LEC Design by Building Type 

Building 

Type

Percentage 

Change

APART04 -21.6

APART06 -23.3

DORMI04 -22.6

DORMI06 -22.8

HOTEL15 -20.0

HIGHS02 -18.5

OFFIC03 -25.3

OFFIC08 -22.8

OFFIC16 -18.5

RETAIL1 -21.0

RSTRNT1 -35.6

Average -22.9

Table 6-4 shows that the nationwide average percentage change in life-cycle costs varies 

significantly over increasing study period lengths, with the average change across all 

location-building type combinations ranging from -3.8 % to -1.1 %. 

Table 6-4 National Average Percentage Change in Life-Cycle Costs from Adoption 

of the LEC Design by Building Type and Study Period Length 

Building 

Type

Study Period Length

1 5 10 15 20 25 30 35 40

APART04 -1.1 0.0 -0.1 -0.5 -0.4 -0.5 -0.7 -0.8 -0.7

APART06 -0.1 0.1 -0.2 -0.6 -0.6 -0.7 -0.9 -1.1 -1.0

DORMI04 -7.0 -1.6 -1.2 -1.5 -1.3 -1.4 -1.5 -1.6 -1.5

DORMI06 0.5 -0.3 -0.6 -1.1 -1.0 -1.2 -1.4 -1.6 -1.5

HOTEL15 1.4 0.3 -0.1 -0.6 -0.7 -1.0 -1.2 -1.4 -1.4

HIGHS02 -1.5 -1.2 -1.3 -1.6 -1.6 -1.8 -2.0 -2.2 -2.1

OFFIC03 -10.1 -2.7 -2.2 -2.4 -2.1 -2.3 -2.4 -2.6 -2.5

OFFIC08 -4.1 -2.2 -2.1 -2.5 -2.2 -2.4 -2.5 -2.7 -2.6

OFFIC16 2.1 0.8 0.3 -0.4 -0.4 -0.7 -1.0 -1.2 -1.2

RETAIL1 -9.1 -0.3 -0.1 -0.6 -0.3 -0.5 -0.8 -0.9 -0.8

RSTRNT1 -12.2 -5.2 -4.2 -5.0 -4.7 -5.0 -5.3 -5.4 -5.4

Average -3.8 -1.1 -1.1 -1.5 -1.4 -1.6 -1.8 -1.9 -1.9

Figure 6-1 shows the graphical representation of the national average change in life-cycle 

costs by building type. For a 1-year study period, the average percentage change in lifecycle costs ranges from -12.2 % to 2.1 % depending on the building type. The significant 

variation is driven by the residual value of the building and its components. Since the 

study period is only one year, the residual values are almost as large as the first costs of 

building construction, amplifying even minor variations in life-cycle costs. 
28

Figure 6-1 Nationwide Average Percentage Change in Life-cycle Costs from 

Nationwide Adoption of the LEC Design by Building Type and Study Period Length

From the 1-year to 10-year study period, there is a convergence towards zero followed by 

a slow but steady decrease from a 10-year to a 40-year study period. Building types that 

are not cost-effective for a 1-year study period slowly become cost-effective as the study 

period length increases. Building types that are cost-effective for a 1-year study period 

remain cost-effective for all longer study period lengths. All building types are costeffective for study period lengths of 15 years or greater. 

6.1.2 Results by Building Type 

Table 6-5 shows the simple average changes by building type, in percentage terms, from 

adopting the LEC design for a 10-year study period. The restaurant realizes the greatest 

reductions while the high school realizes the smallest reductions in energy use, energy 

costs, and energy-related carbon emissions. 

The occupant activity is the primary driver of the results for the high school, which is 

heavily occupied during the school year and lightly occupied during the summer months. 

Some of the energy efficiency measures decrease heat gains, which lead to lower cooling 

loads during warmer months and greater heating loads during the colder months. A 

significant portion of the reductions in electricity consumption during these colder 

months is offset by increases in natural gas consumption required to meet the increased 

heating loads. Thus, a greater portion of the high school’s energy use occurs during the 

colder months relative to other building types. The combination of more energy use 

occurring during the colder months and the offsetting increase in natural gas consumption 

during those months leads to a smaller overall percentage reduction in energy use for 

high schools. 

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

1 5 10 15 20 25 30 35 40

Average Percentage Change in LCC

Study Period

APART04

APART06

DORMI04

DORMI06

HOTEL15

HIGHS02

OFFIC03

OFFIC08

OFFIC16

RETAIL1

RSTRNT1
29

One of the reasons that the restaurant realizes the greatest reductions in energy use is that 

the restaurant has the smallest plug and process loads in terms of watts per unit of floor 

area. Since the plug and process load is the only electricity use not impacted by the 

energy efficiency measures adopted in this study, a greater fraction of energy use can be 

decreased for restaurants relative to the other building types. 

The restaurant realizes the greatest life-cycle cost savings while the 16-story office 

building is the only building to realize an increase in life-cycle costs, on average. Overall, 

all buildings realize significant reductions in energy use, energy costs, and carbon 

emissions.

Table 6-5 Nationwide Average Percentage Change for Adoption of the LEC Design 

by Building Type, 10-Year 

Building 

Type

Percentage Change

Energy Use Energy Cost Carbon LCC

APART04 -14.8 -21.2 -21.6 -0.1

APART06 -15.6 -22.9 -23.3 -0.2

DORMI04 -16.9 -22.2 -22.6 -1.2

DORMI06 -15.2 -22.4 -22.8 -0.6

HOTEL15 -13.9 -19.6 -20.0 -0.1

HIGHS02 -10.6 -18.0 -18.5 -1.3

OFFIC03 -23.0 -25.2 -25.3 -2.2

OFFIC08 -21.5 -22.8 -22.8 -2.1

OFFIC16 -15.3 -18.3 -18.5 0.3

RETAIL1 -18.9 -20.9 -21.0 -0.1

RSTRNT1 -30.7 -35.4 -35.6 -4.2

Average -17.8 -22.6 -22.9 -1.1

6.1.3 Results by Climate Zone 

Table 6-6 shows the nationwide average change in energy use by ASHRAE climate zone 

for the adoption of the LEC design relative to current state energy codes for all building 

types. The average reduction in energy use nationwide is 17.8 %. Zone 1 realizes the 

greatest average reduction in energy use, 22.1 %, while Zone 8 realizes the smallest, 

10.2 %. For Zone 1 through Zone 5, the warmer the climate the greater the reduction in 

energy use, which is a result of the energy efficiency improvement options considered in 

the LEC design. Warmer climates have an additional option (adding overhangs) that is 

not beneficial in the colder climates because solar heat gains are beneficial in cold 

climates and harmful in warm climates. 

Zone 7 realizes a greater overall average reduction in energy use (19.8 %) than Zone 6 

(16.1 %), Zone 5 (14.9 %), or Zone 4 (18.6 %). To explain this result, the average 
30

percentage change in energy use by climate zone is segmented by a location’s current 

energy code in Table 6-6. Considering only the states that have adopted ASHRAE 

90.1-2007, the average percentage reduction in energy use consistently decreases from 

Zone 4 (-15.7 %) to Zone 7 (-11.1 %), where the warmer the climate zone, the greater the 

reduction in energy use. 

Table 6-6 Average Percentage Change in Energy Use for LEC by Climate Zone and 

State Energy Code 

Climate 

Zone/Subzone

Percentage Change by State Energy Code

1999 2001 2004 2007 All

1 -23.1 -21.2 -22.1

2 -38.3 -26.4 -18.2 -20.7

A -37.4 -18.3 -19.3

B -39.2 -26.4 -17.6 -27.4

3 -32.8 -27.4 -19.1 -18.6 -21.3

A -32.8 -27.4 -18.5 -17.3 -22.6

B -21.3 -19.7 -19.8

C -17.5 -17.5

4 -27.4 -26.4 -19.0 -15.7 -18.6

A -26.7 -26.4 -19.0 -15.8 -19.5

B -31.0 -16.9 -19.7

C -14.9 -14.9

5 -27.8 -25.1 -17.1 -13.3 -14.9

A -25.2 -22.8 -13.1 -13.5

B -30.4 -25.9 -17.1 -14.3 -17.8

6 -23.0 -22.0 -16.1 -12.9 -16.1

A -21.9 -20.8 -16.1 -12.5 -15.1

B -23.8 -22.7 -13.3 -17.5

7 -22.7 -20.1 -11.1 -19.8

8 -10.2 -10.2

Grand Total -25.5 -25.2 -19.1 -15.3 -17.8

Table 6-7 shows that the overall average reduction in energy costs over a 10-year study 

period ranges from 21.0 % to 25.5 % depending on the climate zone. The greatest overall 

reductions in energy costs are realized by cities located in Zone 7 followed by Zone 3. 

Similar to energy use, this result can largely be explained by segmenting the average 

percentage change in energy costs for a climate zone by a location’s current energy code.

Considering only the locations that have adopted ASHRAE 90.1-2007, the average 

percentage reductions in energy costs trend lower from the warmer to colder climate 

zones. However, there is some additional variation that results from each location’s 

average cost per unit of energy. For example, cities in Zone 3 realize the greatest 
31

reductions in energy costs, particularly the cities in California located in Subzone 3C,

because the state average cost of electricity in California is the 9th highest in the United 

States, and 2nd highest behind Hawaii of all states that have cities located in the warmer 

climate zones (Zone 1 through Zone 4). 

Table 6-7 Average Percentage Change in Energy Costs for LEC by Climate Zone 

and State Energy Code, 10-Year 

Climate 

Zone/Subzone

Percentage Change by State Energy Code

1999 2001 2004 2007 All

1

-23.1 -21.3 -22.2

2

-39.5 -26.4 -20.4 -22.6

A -39.1 -20.4 -21.4

B

-39.9 -26.4 -20.0 -28.2

3

-36.8 -33.7 -22.9 -22.2 -25.3

A -36.8 -33.7 -22.3 -20.2 -26.4

B

-25.0 -23.4 -23.5

C

-25.0 -25.0

4

-33.5 -30.2 -21.9 -20.2 -23.2

A -32.9 -30.2 -21.9 -20.3 -24.0

B

-37.2 -23.3 -26.1

C

-18.8 -18.8

5

-34.9 -33.4 -21.8 -19.4 -21.0

A -33.3 -26.5 -19.5 -20.0

B

-36.4 -35.7 -21.8 -18.8 -23.3

6

-30.8 -31.6 -17.7 -16.7 -21.2

A -29.7 -28.5 -17.7 -16.7 -19.8

B

-31.7 -33.2 -16.7 -23.0

7

-30.4 -19.7 -16.8 -25.5

8

-23.4 -23.4

Grand Total -32.4 -32.3 -21.8 -19.7 -22.6

Average energy-related carbon emissions are assumed constant across study period 

lengths. The data reported in Table 6-8 show that the average reduction in energy-related 

carbon emissions for the LEC design ranges from 18.5 % to 25.8 % depending on climate 

zone. Even though carbon emissions are a function of electricity and natural gas 

consumption, greater reductions in energy use do not necessarily lead to greater 

reductions in carbon emissions. The greatest reductions in carbon emissions occur in 

Zone 3 (25.8 %) followed by Zone 7 (25.1 %). The lowest reduction occurs in Zone 8 

(18.5 %) followed by Zone 6 (21.3 %) and Zone 5 (21.4 %).
32

Similar to energy use and energy costs, this result can largely be explained by segmenting 

the average percentage change in energy-related carbon emissions for a climate zone by a 

location’s current energy code. Considering only the states that have adopted ASHRAE 

90.1-2007, the average percentage reductions in carbon emissions trend lower from the 

warmer to colder climate zones. However, there is some additional variation that results 

from two factors. First, cities that realize a greater shift in energy use from electricity to 

natural gas realize greater reductions in carbon emissions. Second, cities with a greater 

differential in average emissions per unit of electricity relative to natural gas will realize 

greater reductions per unit of energy shifted from natural gas to electricity. 

Table 6-8 Average Change in Energy-related Carbon Emissions for LEC by 

Climate Zone and State Energy Code 

Climate 

Zone/Subzone

Percentage Change by State Energy Code

1999 2001 2004 2007 All

1

-23.9 -22.0 -23.0

2

-40.1 -27.3 -21.0 -23.2

A -39.9 -21.0 -22.0

B

-40.3 -27.3 -20.3 -28.8

3

-38.8 -36.2 -23.6 -22.2 -25.8

A -38.8 -36.2 -23.3 -21.3 -27.9

B

-24.5 -22.9 -23.0

C

-21.8 -21.8

4

-36.3 -34.8 -23.0 -20.7 -24.3

A -35.9 -34.8 -23.0 -21.0 -25.6

B

-38.7 -22.4 -25.7

C

-19.3 -19.3

5

-37.0 -36.1 -21.5 -19.6 -21.4

A -36.2 -33.9 -19.8 -20.5

B

-37.9 -36.8 -21.5 -18.9 -23.4

6

-31.0 -32.8 -18.4 -16.7 -21.3

A -30.4 -29.6 -18.4 -16.9 -20.1

B

-31.5 -34.5 -16.4 -23.0

7

-29.3 -20.1 -17.8 -25.1

8

-18.5 -18.5

Grand Total -32.9 -35.1 -22.3 -20.0 -22.9

The results reported in Table 6-9 show that changes in life-cycle costs vary across climate 

zones and study periods. The LEC design is cost-effective for all study periods across all 

climate zones. The percentage reduction in life-cycle costs becomes smaller from the 1-

year to 5-year and 10-year study periods, and then slowly increases from the 10-year to 

40-year study period. For study period lengths of 10 years or greater, the warmer the 
33

climate zone, the greater the percentage reduction in life-cycle costs. For example, the 

average percentage reduction for the 40-year study period ranges from 3.0 % in Zone 1 to 

0.6 % for Zone 8. 

Table 6-9 Average Percentage Change in Life-Cycle Costs for LEC by Climate 

Zone and Study Period 

Climate 

Zone/Subzone

Study Period Length

1 5 10 15 20 25 30 35 40

1 -10.7 -3.3 -2.5 -2.9 -2.6 -2.7 -2.9 -3.0 -3.0

2 -2.7 -1.4 -1.4 -2.1 -2.0 -2.1 -2.3 -2.5 -2.4

A -1.8 -1.1 -1.2 -1.9 -1.7 -1.9 -2.1 -2.2 -2.2

B -6.9 -2.8 -2.5 -3.4 -3.1 -3.3 -3.5 -3.6 -3.6

3 -3.1 -1.3 -1.3 -1.6 -1.8 -2.2 -2.4 -2.5 -2.4

A -2.9 -1.3 -1.3 -1.7 -2.0 -2.4 -2.6 -2.7 -2.6

B -3.4 -1.5 -1.4 -1.6 -1.8 -2.1 -2.3 -2.4 -2.2

C -2.8 -0.6 -0.6 -0.9 -0.6 -1.0 -1.4 -1.5 -1.4

4 -2.3 -0.9 -0.9 -1.8 -1.6 -1.8 -2.1 -2.2 -2.1

A -2.2 -0.9 -1.0 -2.0 -1.8 -2.0 -2.3 -2.5 -2.4

B -2.7 -1.2 -1.2 -2.0 -1.8 -2.1 -2.4 -2.6 -2.4

C -2.4 -0.4 -0.4 -1.1 -0.8 -0.9 -1.2 -1.3 -1.2

5 -4.6 -1.2 -1.0 -1.4 -1.2 -1.3 -1.5 -1.7 -1.7

A -3.9 -0.9 -0.9 -1.2 -1.0 -1.2 -1.4 -1.6 -1.6

B -6.1 -1.7 -1.4 -1.8 -1.5 -1.6 -1.8 -2.0 -1.9

6 -3.6 -0.8 -0.8 -1.0 -0.8 -0.9 -1.0 -1.2 -1.1

A -3.8 -0.9 -0.9 -1.1 -0.9 -1.1 -1.2 -1.3 -1.2

B -3.4 -0.7 -0.7 -0.9 -0.7 -0.8 -0.9 -1.0 -0.9

7 -3.4 -0.8 -1.0 -1.2 -1.1 -1.2 -1.4 -1.5 -1.5

8 -19.4 -1.7 -0.6 -0.5 -0.3 -0.4 -0.6 -0.7 -0.6

Average -3.8 -1.1 -1.1 -1.5 -1.4 -1.6 -1.8 -1.9 -1.9

6.1.4 Results by State Energy Code 

One purpose of this study is to determine which states could benefit the most from 

adopting a more stringent state energy code for commercial buildings. It would be 

expected that states with energy codes based on older editions of ASHRAE 90.1, or no 

energy code at all, would realize greater benefits from adopting the LEC design because 

buildings in those states are expected to be built in a less energy efficient manner. Figure 

6-2 shows the 14 states with energy codes based on an older edition of ASHRAE 90.1

(-2001) or that have no energy code,17 many of which are located in the central U.S. as 

well as a few states in the south, West Virginia, Arizona, Maine, and Alaska. 

 

17 All maps are generated in ArcMap 10.1. 
34

Figure 6-2 States with Energy Standard Editions 2001 or Older or No energy code

It is necessary to assume a particular study period length because energy costs fluctuate 

on an annual basis. A 10-year study period is used as the baseline because it is one of the 

most realistic investor time horizons out of the 9 study period length options in BIRDS.

State benefit comparisons are made based on the simple average changes for the cities 

analyzed in each state by building type. One building type is chosen to illustrate the 

detailed analysis possible with the powerful BIRDS database compiled for this study. 

Energy use, energy costs, life-cycle costs, and cradle-to-grave energy-related carbon 

emissions are analyzed for the most common existing building type, small office 

buildings. Summary results for the other 10 building types are reported in Table B-1

through Table B-10 in Appendix B. The same interpretations hold for the other ten 

building types. No states have adopted the LEC design so all should realize impacts 

across the four metrics listed above. 

Table 6-10 summaries the percentage changes in energy use, energy costs, carbon 

emissions, and life-cycle costs for the 3-story office building. On average, adoption of the 

LEC design for a 3-story office building decreases energy use, energy costs, and energyrelated carbon emissions by more than 20 % each while reducing life-cycle costs. These 

detailed results can be readily analyzed in mappings of the United States. 
35

Table 6-10 Average Percentage Change by State, 3-Story Office Building, 10-Year 

State

Percentage Change

State

Percentage Change

Energy 

Use

Energy 

Cost

Carbon LCC Energy 

Use

Energy 

Cost

Carbon LCC

AK -25.5 -27.6 -26.9 -0.5 MT -18.0 -20.1 -19.9 -1.9

AL -36.3 -36.6 -36.8 -0.7 NC -21.9 -23.3 -23.7 -2.1

AR -30.4 -33.0 -33.9 -3.8 ND -29.5 -30.5 -30.6 0.8

AZ -34.7 -34.9 -35.0 -3.1 NE -18.2 -23.0 -23.5 -2.3

CA -24.5 -25.5 -25.1 -3.0 NH -18.1 -20.4 -20.1 -2.8

CO -29.3 -32.1 -32.4 -5.5 NJ -19.6 -23.6 -22.9 -2.5

CT -17.9 -23.4 -21.8 -3.1 NM -23.3 -25.5 -25.6 -3.1

DE -20.0 -22.7 -23.2 -3.4 NV -25.3 -26.7 -26.3 -4.3

FL -24.0 -24.3 -24.3 -2.3 NY -16.9 -22.0 -20.2 -3.0

GA -21.6 -22.9 -23.3 -1.2 OH -17.5 -22.1 -22.7 -2.5

HI -28.0 -28.0 -28.0 -5.7 OK -30.8 -33.7 -35.7 2.0

IA -17.7 -21.4 -21.9 -1.7 OR -21.2 -23.5 -23.6 -3.5

ID -19.7 -22.0 -22.1 -2.7 PA -17.5 -21.5 -22.1 -2.7

IL -17.5 -23.0 -23.0 -2.4 RI -18.5 -22.5 -22.3 -2.8

IN -18.3 -22.4 -23.0 -2.1 SC -23.8 -24.9 -25.0 -2.0

KS -31.9 -34.3 -35.1 0.7 SD -28.1 -30.2 -30.4 -0.7

KY -19.8 -22.4 -23.5 -2.4 TN -25.3 -25.8 -25.9 -2.6

LA -21.9 -22.7 -23.0 -0.3 TX -21.7 -23.1 -23.1 -1.9

MA -17.6 -22.8 -21.8 -2.6 UT -20.8 -24.6 -23.7 -3.0

MD -20.0 -23.4 -23.1 -3.0 VA -22.1 -24.1 -24.5 -2.2

ME -31.1 -31.6 -31.6 -0.7 VT -17.6 -20.1 -19.8 -2.6

MI -16.4 -21.0 -21.5 -2.6 WA -19.6 -21.9 -22.4 -2.7

MN -26.1 -23.7 -23.4 -1.8 WI -17.5 -20.1 -20.2 -1.7

MO -31.6 -33.4 -34.4 1.4 WV -30.4 -31.4 -32.4 -4.3

MS -41.9 -39.1 -39.0 0.4 WY -30.1 -31.8 -31.8 0.3

Avg. -23.0 -25.2 -25.3 -2.2

6.1.4.1 Energy Use, Energy Cost, and Carbon Emissions Savings 

Figure 6-3 overlays Figure 6-2 and displays the average percentage energy savings, 

energy cost savings, and carbon emissions reduction for a 10-year study period by state. 

The states with codes based on older editions of ASHRAE 90.1, or no energy code at all, 

are shown with cross hatching and bolded state borders. Figure 6-3 shows that 31 of 50 

states realize energy use savings of 20 % or more by adopting the LEC design over their 

current state energy code. Many of the states that realize the greatest energy use savings 

are the ones that currently have energy codes based on older editions of ASHRAE 90.1, or 

no energy code at all. Of the 18 states that realize energy use savings of at least 25 %, 14

are states with either no energy code or a code based on ASHRAE 90.1-1999 or ASHRAE 

90.1-2001, including all 10 states that realize energy use savings of more than 30 %.

The state average percentage reductions in energy costs and carbon emissions are highly 

correlated with the percentage reductions in energy use. However, the reductions in 

energy costs and carbon emissions tend to be greater than the reductions in energy use. 

Figure 6-3 allows for a comparison of the three impacts. A total of 19 states realize an 

average reduction in energy use of less than 20 %. Meanwhile, all states realize an 
36

average reduction in energy costs of greater than 20 % and two states realize an average 

reduction in carbon emissions of less than 20 %.

Figure 6-3 Average Energy Use, Energy Cost, and Carbon Emissions Savings by 

State, 3-Story Office Building, 10-Year 

As has been previously discussed, there are two fuel types consumed in each building, 

natural gas for heating and electricity for all other energy demands (e.g., cooling, plug 

and process loads, etc.). Electricity and natural gas have different price and emissions rate 

profiles, with natural gas costing less and being associated with fewer emissions per unit 

of energy consumed. As a result, the fuel source of reductions in energy use is an 

important determining factor for the relative savings in energy costs and energy-related 

carbon emissions per unit of savings in energy use. 

Consider the example in Table 6-11, with three alternative building designs that decrease 

energy use from 100 units to 50 units. Each alternative decreases total energy use by the 

same amount (50 units or 50 %), but the source of the reduction in energy use varies 

significantly. Alternative #1 decreases electricity consumption by a greater percentage 

than natural gas consumption. Alternative #2 decreases electricity and natural gas 
37

consumption by the same percentage. Alternative #3 decreases electricity consumption 

by a smaller percentage than natural gas consumption. 

Table 6-11 Fuel Source Reduction Example 

Design Energy Use % Change

Total Elect. Gas %Δ Total %Δ Elect. %Δ Gas

Baseline 100 50 50

(1) Electricity Reduction Heavy 50 10 40 -50 % -80 % -20 %

(2) Equal Reduction 50 25 25 -50 % -50 % -50 %

(3) Natural Gas Reduction Heavy 50 40 10 -50 % -20 % -80 %

The total emissions and energy costs are estimated for the baseline and each building 

design alternative in Table 6-12 based on the average state energy prices and emissions 

rates.18 The percentage changes in carbon emissions and energy costs are greatest for 

Alternative #1, with reductions of 65 % and 66 %, respectively. Alternative #2 realizes 

reductions in emissions and energy costs of 50 %. Alternative #3 realizes the smallest 

percentage reductions in emissions (35 %) and energy costs (34 %). 

Table 6-12 Emissions and Energy Costs Associated with Fuel Source Reductions 

Design Emissions Energy Costs Relative to Δ

Energy Use

Total Δ Δ% Total Δ Δ%

Baseline 49 300 650

(1) Electricity Reduction Heavy 7 450 -32 210 -65 % 220 -430 -66 % > 50 %

(2) Equal Reduction 18 625 -24 650 -50 % 325 -325 -50 % = 50 %

(3) Natural Gas Reduction Heavy 29 800 -17 090 -35 % 430 -220 -34 % < 50 %

Based on these results there are three potential outcomes. First, if the percentage 

reduction in electricity is greater than the percentage reduction in natural gas 

consumption, then the percentage reduction in energy costs and carbon emissions are 

greater than the percentage reduction in energy use. Second, if the percentage reduction 

in electricity is equal to the percentage reduction in natural gas consumption, then the 

percentage reduction in energy costs and carbon emissions are equal to the percentage 

reduction in energy use. Third, if the percentage reduction in electricity is less than the 

percentage reduction in natural gas consumption, then the percentage reductions in 

energy costs and carbon emissions are less than the percentage reduction in energy use. 

 

18 Average state electricity price is 10₵/kWh; average state natural gas price is 3₵/kWh; average state 

electricity emissions rate is 745 tCO2e/GWh; average state natural gas emissions rate is 241 tCO2e/GWh 
38

Now consider an example from the BIRDS database: the average energy use for high 

schools in Tennessee. Figure 6-4 shows the total energy use for Tennessee’s baseline 

building design, ASHRAE 90.1-2004, is greater than the energy use for the two building 

design alternatives, the ASHRAE 90.1-2007 and LEC designs. However, the fuel source 

of the changes in total energy use for ASHRAE 90.1-2007 and LEC designs are quite 

different. 

Figure 6-4 Total Energy Use – High School – Tennessee 

Figure 6-5 shows the change in energy use for both building designs by fuel source. For 

the ASHRAE 90.1-2007 design, natural gas consumption realizes a greater total reduction 

of 13.5 kWh (46 176 Btu) relative to a reduction in electricity consumption of 6.3 kWh 

(21 494 Btu). Meanwhile, adopting the LEC design leads to a large reduction in 

electricity consumption 95.5 kWh (336 172 Btu) while increasing natural gas 

consumption 16.6 kWh (56 571 Btu). Not only is electricity the primary fuel source for 

total energy use reductions, there is a shift in fuel consumption from electricity to natural 

gas. 

1,218,995 1,197,501

882,823

960,173 913,997

1,016,744

0

500,000

1,000,000

1,500,000

2,000,000

2004 2007 LEC

kWh

Standard

Natural Gas

Electricity
39

Figure 6-5 Change in Energy Use – High School – Tennessee 

Figure 6-6 shows the percentage change in energy use for both building designs and fuel 

sources. For the ASHRAE 90.1-2007 design, natural gas consumption realizes a greater 

percentage reduction (5.1 %) than electricity consumption (1.8 %), which implies that the 

percentage reduction in energy use will be greater than the percentage reductions in 

energy costs and carbon emissions. Adopting the LEC design leads to a large percentage 

decrease in electricity consumption (-38.1 %) and a small percentage increase natural gas 

consumption (5.6 %). Not only does electricity consumption decrease by a greater 

percentage than natural gas, electricity accounts for greater than 100 % of the reduction 

in total energy use, which implies that the percentage reduction in energy costs and 

carbon emissions will be greater than the reduction in energy use. 

Figure 6-6 Percentage Change in Energy Use – High School – Tennessee 

-21,494

-336,172

-46,176

56,571

-67,670

-279,601

-350,000

-300,000

-250,000

-200,000

-150,000

-100,000

-50,000

0

50,000

100,000

2007 LEC

kWh

Standard

Delta Electricity

Delta Gas

Delta Total

-1.8%

-38.1%

-5.1%

5.6%

-3.2%

-14.7%

-40%

-30%

-20%

-10%

0%

10%

2007 LEC

Percent Change

Standard

%Delta Electricity

%Delta Gas

%Delta Total
40

For the LEC design, some of the reduction in electricity consumption is “offset” by an 

increase in natural gas consumption. A “positive offset” occurs when electricity 

consumption decreases and natural gas consumption increases. A “negative offset” 

occurs when both electricity and natural gas consumption decrease. The greater the 

percentage “offset,” the greater the percentage reduction in energy costs and carbon 

emissions per percentage reduction in energy use. The offset will be discussed in more 

detail in Section 6.3.1.

6.1.4.2 Life-Cycle Cost Savings 

Figure 6-7 overlays Figure 6-2 with the average life-cycle cost savings for the 3-story 

office building over 10 years by state from adopting the LEC design. The resulting map 

shows two interesting trends. First, all states that realize an increase in life-cycle costs on 

an average percentage basis as a result of adopting the LEC design as its state energy 

code currently have no state energy code. The energy cost savings of the more efficient 

LEC design are not enough to overwhelm the additional construction and MRR costs 

associated with the required energy efficiency measures. Second, states located in the 

central and southern U.S. tend to realize life-cycle cost savings less than 2 %. States 

located in the West and Northeast U.S. tend to realize life-cycle cost savings greater than 

2 %, which may be a result of greater energy cost savings due to higher energy prices. 

Figure 6-7 Average Life-Cycle Cost Savings by State, 3-Story Office Building, 

10-Year 

For a 3-story office building and a 10-year study period, states that currently have no 

energy code or energy codes based on older editions of ASHRAE 90.1 have the most to 

gain in percentage terms in energy use, energy cost, and carbon emissions savings in 

adopting more stringent state energy codes. However, some of these same states realize 

an average percentage increase in life-cycle costs over the same 10-year study period, 

raising questions as to the cost-effectiveness of these additional energy efficiency 

measures. 
41

6.2 Total Changes 

The average percentage changes in energy use, energy costs, energy-related carbon 

emissions, and life-cycle costs reported in Section 6.1 do not account for the amount of 

new floor area for each building type in a state, which may have a significant impact on 

the results. 

6.2.1 State-Level Total Savings 

Estimating the magnitude of the total impacts in a state controls for new floor area and 

determines which states would benefit the most from adopting the LEC design as their 

state energy code. The total changes in the four impacts from adopting the LEC design 

for a state are calculated using Formula 1 defined in Section 5.4. Based on this formula, 

two variables impact the magnitude of the total changes in a state: the amount of new 

commercial building construction and the average changes per unit of floor area. 

Figure 6-8 shows the amount of new floor area (1000 m2) constructed annually for each 

of the 50 states from 2003 to 2007. States with a greater amount of new floor area 

constructed (California, Florida, and Texas) are expected to realize greater reductions in 

energy use, energy costs, and carbon emissions. 

Figure 6-8 Average Annual New Floor Area by State

Table C-1 in Appendix C shows the total savings in energy use, energy costs, carbon 

emissions, and life-cycle costs from adopting the LEC design as the commercial building 

energy code for all 50 states for a 10-year study period. In general, the greater the amount 

of new floor area, the greater the reductions in energy use, energy costs, and carbon 

emissions. The relative total changes across states, shown in Figure 6-9, are significantly 

different than the relative percentage changes shown in Figure 6-3, which emphasizes the 

importance of controlling for the amount of new floor area for each building type in 

determining the magnitude of the impacts of adopting the LEC design. The total change 

in energy use for a state is driven by the amount of new floor area constructed in a state. 

California, Florida, and Texas realize the greatest reductions in energy use (1.9 TWh to 
42

3.8 TWh). In comparison, states with the smallest amount of new floor area (Alaska, 

Delaware, Montana, Rhode Island, Vermont, and Wyoming) realize savings of less than 

0.1 TWh. 

Figure 6-9 Total Energy Use, Energy Costs, and Carbon Emissions Savings by 

State, 10-Year 

Figure 6-9 shows a strong correlation between total savings in energy use and total 

savings in energy costs and carbon emissions. California, Florida, and Texas realize the 

greatest reductions in energy costs while Florida and Texas realize the greatest reductions 

in carbon emissions. The relative total reductions in energy costs and carbon emissions 

vary from total reductions in energy use to some extent. The reasons for this variation 

will be discussed in Section 6.3.1.3 and Section 6.3.1.4, respectively. 
43

Figure 6-10 shows a strong correlation between total savings in energy use shown in 

Figure 6-9 and total savings in life-cycle costs. California, Florida, and Texas realize the 

greatest total life-cycle cost savings. The relative total reductions in life-cycle costs vary 

from total reductions in energy use to some extent, particularly for states with no energy 

code. The reasons for this variation will be discussed in Section 6.3.1.2 and Section 6.4.2.

Figure 6-10 Total Life-Cycle Cost Savings by State, 10-Year 

Only two states realize an increase in life-cycle costs (Oregon and Washington). Neither 

of these two states realized an increase in life-cycle costs on a percentage basis. 

Additionally, seven states that realize an increase in life-cycle costs on a percentage basis 

for the 3-story office building (see Figure 6-7) realize a total life-cycle cost decrease 

(Alaska, Kansas, Mississippi, Missouri, North Dakota, Oklahoma, and Wyoming). These 

results emphasize the importance of accounting for the building types associated with the 

new floor area constructed in a state to determine where adopting the LEC design is lifecycle cost-effective.

6.2.2 Regional and National Total Savings 

The nationwide changes in the four impacts from adopting the LEC design are calculated 

using Formula 2 from Section 5.4, where the state-level savings are summed across all 

fifty states for each impact. 

Table 6-13 shows the total changes in energy use, energy costs, energy-related carbon 

emissions, and life-cycle costs for one year’s worth of construction for a 10-year study 

period aggregated at the Census region and national level. The greater the amount of new 

floor area constructed in a Census region, the greater the total reduction in energy use, 

energy costs, and life-cycle costs. This condition does not strictly hold for the total 

reduction in carbon emissions because the total reduction in the Midwest Census Region 

is greater than the total reduction in the West Census Region. The reason for this 

variation will be discussed in Section 6.3. The nationwide reductions total 34.4 TWh in 

energy consumption, $2.8 billion in energy costs, 26.3 million metric tons in 
44

energy-related carbon emissions, and $1.0 billion in life-cycle costs for a 10-year study 

period.

Table 6-13 Total Reductions by Census Region from Adoption of the LEC Design, 

10-Year 

Census 

Region

Average Annual New 

Floor Area

1000 m

2

(1000 ft2)

Energy 

Use 

(GWh)

Energy 

Costs

($million)

Carbon 

(1000 tCO2e)

LCC 

($million)

Northeast 22 395 (241 056) 3437 399 2332 125

Midwest 29 510 (317 641) 6621 459 6219 136

South 67 299 (724 394) 16 427 1208 12 890 488

West 36 144 (389 056) 7956 703 4878 300

Total 155 348 (1 672 147) 34 441 2769 26 319 1048

6.3 Changes per Unit of Floor Area and Energy Use Savings 

Total savings in energy use, energy costs, carbon emissions, and life-cycle costs are 

highly correlated. However, there are a number of factors that lead to significant variation 

in relative savings, each of which will be discussed in this section.

6.3.1 State Level Changes 

There is significant variation in relative savings across states for each of the four impacts 

for a number of reasons, including current state energy code requirements, newly 

constructed building stock mix and size, climate zone, electricity costs, electricity 

production fuel mix (average emissions rate), and the relative percentage changes in fuel 

types consumed by the building. 

6.3.1.1 Energy Use Savings per Unit of Floor Area 

Total energy use savings varies across states for a number of reasons. First, states with 

more newly constructed commercial floor area realize greater reductions in energy use. 

Second, states located in warmer climate zones realize greater reductions in energy use 

than the states located in colder climate zones because the buildings in warmer climates 

benefit more from the overhangs and daylighting installed in the LEC design. Third, a 

state’s current state energy code for commercial buildings drives the variation in energy 

use. 

Table C-2 shows the 10-year reduction in energy use per unit of newly constructed floor 

area sorted by state in decreasing order. The reduction in energy use per unit of floor area 

is primarily driven by the state’s adopted energy code for commercial buildings. Fourteen 

of the fifteen states with the greatest per unit reduction from adoption of the LEC design 

have no state energy code or have ASHRAE 90.1-2001 as their state energy code. 
45

Additionally, only two of the top 21 states, in terms of per unit savings, have adopted 

ASHRAE 90.1-2007. These results, shown in Figure 6-11, can be compared to the average 

percentage changes in energy use in Figure 6-3. After controlling for the amount of new 

floor area, the relative savings across states correlates much closer to the relative average 

percentage changes in energy use. However, the correlation is not perfect because the 

total changes weight building types based on new floor area constructed in a state. 

Figure 6-11 Energy Use Savings per Unit of Floor Area by State, 10-Year 

6.3.1.2 Life-Cycle Cost Savings per Unit of Floor Area 

The relative change in life-cycle costs per unit of new floor area is shown in Table C-3. 

After controlling for the amount of new floor area, states that have adopted ASHRAE 

90.1-2001 as their state energy code (Arkansas, Colorado, and West Virginia) realize 

some of the greatest relative life-cycle cost savings of adopting the LEC design. There is 

significant variation in life-cycle cost savings for the ten states with no state energy code, 

with the relative ranking ranging from 4th (Arizona) to 48th (North Dakota). These results, 

shown in Figure 6-12, can be compared to the average percentage changes in life-cycle 

costs in Figure 6-7. Once controlling for the amount of new floor area, the relative 

savings across states correlates better with the relative percentage changes in energy use. 

However, the correlation is not perfect because the total changes weight building types 

based on new floor area constructed. 
46

Figure 6-12 Life-Cycle Cost Savings per Unit of Floor Area by State, 10-Yr

6.3.1.3 Energy Cost Savings per Unit of Energy Use Savings 

In general, the states that realize the greatest reductions in energy use also realize the 

greatest reductions in energy costs. However, reductions in energy costs are also 

impacted by the per unit costs of electricity and natural gas and the fuel mix of the 

reductions in energy use in a state. Table C-4 shows each state’s reduction in energy costs 

per unit of reduction in energy use, natural gas rate, electricity rate, and the fraction of 

electricity consumption reductions offset by increases in natural gas consumption.19

States with the highest electricity rates tend to realize the greatest reductions in energy 

costs per unit of reduction in energy use. Relative to electricity prices, natural gas prices 

have minimal impacts on the relative reduction because natural gas prices are fairly 

constant across states (excluding Hawaii), and are significantly cheaper per unit of energy 

for all fifty states. 

The correlation between a state’s average electricity price and the savings in energy costs 

per unit of energy reduced is shown in Figure 6-13. States in the Northeast, Great Lakes 

area, California, Hawaii, and Alaska have the highest average electricity prices and 

realize the greatest savings in energy costs per unit of savings in energy use. Meanwhile, 

states with the lowest average electricity prices (Northern Central U.S.) realize the 

smallest energy cost savings per unit of energy use savings. 

 

19 The fraction of electricity offset by natural gas consumption is greater (less) than 100 % (-100 %) when 

natural gas consumption increases (decreases) by a greater amount than electricity consumption decreases. 
47

Figure 6-13 Energy Cost Savings per Unit of Energy Use Savings and Average 

Electricity Price by State 

The electricity price does not explain all the variation across states in energy cost savings 

per unit of energy use savings because there are two sources of energy cost savings: the 

energy cost savings from total energy use reduction, and the energy cost savings from the 

shift of fuel consumption from more expensive electricity to cheaper natural gas. The 

savings from the shift in fuels is a result of two factors: the energy cost savings per unit 

of energy shifted from electricity to natural gas consumption (energy price differential) 

and the amount of energy shifted from electricity to natural gas consumption. The energy 

cost savings increases as the energy price differential increases because the cost savings 

for each unit of electricity “offset” by a unit of natural gas is greater. The greater the 

fraction of electricity consumption shifted to natural gas consumption, or offset, the 

greater the energy cost savings per unit of total energy use savings. 

The metric used to explain the shift in fuel consumption is the “weighted average offset,” 

which is the average percentage offset weighted by the amount of new floor area for each 

building type in a state. Figure 6-14 shows the weighted average offset for each state. 

Most states realize a positive offset (38 of 50). The northern-most states realize the 

smallest offset values (-121.2 % to -25.0 %). The greatest offset values are spread across 

the United States: from the West Coast to the southern central U.S. states to the East 

North Central and Middle Atlantic Census Divisions.
48

Figure 6-14 Weighted Average Offset by State 

Figure 6-15 shows the savings in energy costs per unit of savings in energy use ($/MWh) 

based on the price differential between electricity and natural gas ($/kWh) and the 

weighted average offset (%) for each state. States with a greater energy price differential 

combined with a greater weighted average offset realize the greatest energy cost savings 

per unit of energy use savings. 

Figure 6-15 Average State Energy Cost Savings per Unit of Energy Use Savings by 

Weighted Average Offset and Energy Price Differential 

6.3.1.4 Carbon Emissions Savings per Unit of Energy Use Savings 

In general, the states that realize the greatest reductions in energy use also realize the 

greatest reductions in energy-related carbon emissions. However, reductions in carbon 

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

-40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0

Electricity to Natural Gas Price Differential 

($/kWh)

Weighted Offset (%)

Energy Cost Savings ($/MWh)
49

emissions are also impacted by the per unit emissions rates of electricity and natural gas 

and the fuel mix of the reductions in energy use in a state. Table C-5 shows the weighted 

average fraction of electricity consumption offset by a change in natural gas 

consumption, the average CO2 emission rates for electricity and natural gas, and the 

reduction in cradle-to-grave energy-related carbon emissions per unit of reduction in 

energy use for all 50 states.20 States with the highest emissions rates for electricity 

generation tend to realize the greatest reductions in carbon emissions per unit of 

reduction in energy use. Relative to electricity emissions rates, natural gas has minimal 

impact on the relative reduction because natural gas emissions rates are constant across 

states and are significantly lower per unit of energy for all fifty states. 

The correlation between a state’s average electricity emissions rate and the savings in 

energy-related emissions per unit of energy reduced is shown in Figure 6-16. States in the 

central U.S. and the Rust Belt have the highest average electricity emissions rates and 

realize the greatest savings in carbon emissions per unit of savings in energy use. 

Meanwhile, states with the lowest average electricity emissions rates (most of the states 

in the West Census Region and New England Census Division) realize the smallest 

carbon emissions savings per unit of energy use savings. 

Figure 6-16 Energy-related Carbon Emissions Savings per Unit of Energy Use 

Savings and Average Electricity Emissions Rate by State 

 

20 The fraction of electricity offset by natural gas consumption is greater than 100 % when natural gas 

consumption increases by a greater amount than electricity consumption decreases. The fraction of 

electricity offset by natural gas consumption is less than -100 % when natural gas consumption decreases 

by a greater amount than electricity consumption decreases. 
50

The electricity emissions rate does not explain all the variation across states in 

energy-related carbon emissions savings per unit of energy use savings because there are 

two sources of carbon emission savings: the carbon emissions savings from total energy 

use reduction, and the carbon emissions savings from the shifting of fuel consumption 

from the more carbon intensive electricity to less carbon intensive natural gas. The 

carbon emissions savings increase as the emissions rate differential increases because the 

carbon emissions savings for each unit of electricity “offset” by a unit of natural gas is 

greater. The greater the fraction of electricity consumption reductions offset by increases 

in natural gas consumption, the greater the carbon emissions savings per unit of energy 

use savings. 

Figure 6-17 shows the savings in carbon emissions per unit of savings in energy use 

(tCO2e/GWh) based on the emissions rate differential between electricity and natural gas 

(tCO2e/GWh) and the weighted average offset (%) for each state. States with a greater 

carbon emissions rate differential combined with a greater weighted average offset 

realize the greatest carbon emissions savings per unit of energy use savings. 

Figure 6-17 Average State Carbon Emissions Savings per Unit of Floor Area by 

Weighted Average Offset and Energy Emissions Rate Differential 

6.3.2 Regional and National Level Changes 

Table 6-14 shows the reduction in energy use per unit of newly constructed floor area 

from adopting the LEC design by Census region. States in the South Census Region 

realize the greatest reduction while states in the Northeast Census Region realize the 

150

250

350

450

550

650

750

850

-45.0 -35.0 -25.0 -15.0 -5.0 5.0 15.0 25.0

Emissions Rate Differential (tCO2e/GWh)

Weighted Average Offset (%)

Carbon Emissions Savings (tCO2e/GWh)
51

smallest reduction in energy use per unit of floor area. The nationwide weighted average 

reduction in energy use per unit of floor area is 222 kWh/m2(21 kWh/ft2).

Table 6-14 Energy Use Reduction per Unit of Floor Area for Adoption of the LEC 

Design by Census Region, 10-Year 

State Average Annual 

New Floor Area

1000 m

2

(1000 ft2)

Energy Use 

(GWh) kWh/m2

kWh/ft2

South 67 299 (724 394) 16 427 244 23

Midwest 29 510 (317 641) 6621 224 21

West 36 144 (389 056) 7956 220 20

Northeast 22 395 (241 056) 3437 153 14

Total 155 348 (1 672 147) 34 441 222 21

Table 6-15 shows each Census Region’s natural gas rate, electricity rate, weighted 

average fraction of the reduction in electricity consumption offset by the change in 

natural gas consumption, and average reduction in energy costs from adopting the LEC 

design. The Northeast Census Region has the highest average electricity rate and 

weighted average offset, and realizes the greatest reductions in energy costs per unit of 

reduction in energy use. Meanwhile, the Midwest Census Region has the smallest 

average electricity rate and weighted average offset, and realizes the smallest reductions 

in energy costs per unit of reduction in energy use. 

Table 6-15 Energy Cost Reduction per kWh of Energy Use Reduction for Adoption 

of the LEC Design by Census Region, 10-Year 

State Offset*

(%)

Electricity

Rate*

($/kWh)

Natural Gas

Rate*

($/kWh)

Energy Cost

Reduction

($/kWh)

Northeast 11.6 0.14 0.03 0.12

West 10.3 0.10 0.03 0.09

South 7.3 0.09 0.03 0.07

Midwest -4.6 0.09 0.03 0.07

Total 6.4 0.10 0.03 0.08

*Weighted by energy use savings for a state

Table 6-16 shows each Census Region’s natural gas emissions rate, electricity emissions 

rate, weighted average fraction of the reduction in electricity consumption offset by the 

change in natural gas consumption, and average reduction in carbon emissions from 

adopting the LEC design. The Midwest Census Region has the highest average electricity 

emissions rate, and realizes the greatest reductions in carbon emissions per unit of 

reduction in energy use. Even though the West Census Region does not have the smallest 

average electricity emissions rate, it realizes the smallest reductions in carbon emissions 
52

per unit of reduction in energy use. The Northeast Census Region has a greater offset 

than the West Census Region, leading to the Northeast realizing greater carbon emissions 

savings per unit of energy use savings. 

Table 6-16 Carbon Reduction per GWh of Energy Use Reduction for Adoption of 

the LEC Design by Census Region, 10-Year 

State Offset*

(%)

CO2e

Emissions Rate 

for Electricity*

(t/GWh)

CO2e

Emissions Rate 

for Natural Gas

(t/GWh)

CO2e

Reduction

(t/GWh)

Midwest -4.6 928 241 939

South 7.3 805 241 785

Northeast 11.6 606 241 678

West 10.3 653 241 613

Total 3.7 805 241 764

*Weighted by energy use savings for a state

Table 6-17 shows the average life-cycle cost reduction per unit of new floor area by 

Census Region. The combination of greater energy use savings per unit of floor area and 

higher electricity rates tends to lead to greater life-cycle cost savings from adopting the 

LEC design. The West Census Region realizes the greatest life-cycle cost savings per unit 

of floor area because it has the 2nd greatest energy use savings per unit of floor area and 

the 2nd highest electricity price. Meanwhile the Census regions with the lowest electricity 

rate (Midwest) and the smallest energy use savings per unit of floor area (Northeast) 

realize the lowest and 2nd-lowest life-cycle cost savings per unit of floor area, 

respectively. Other factors that impact life-cycle cost savings include the energy codes 

and local construction costs. 

Table 6-17 Life-Cycle Cost Reductions per Unit of New Floor Area for Adoption of 

the LEC Design by Census Region, 10-Year 

State

Energy Use 

Savings

(kWh/m2)

Electricity

Rate

($/kWh)

LCC 

Savings 

($million)

LCC 

Savings 

($/m2)

LCC 

Savings 

($/ft2)

West 220 0.10 300 8.29 0.77

South 244 0.09 488 7.24 0.67

Northeast 153 0.14 125 5.59 0.52

Midwest 224 0.09 136 4.60 0.43

Total 222 0.10 1048 6.75 0.63
53

6.4 Within-State Impacts of Adopting Low Energy Case Design 

So far, the analysis in this report has focused on across-state, regional, and national 

variations. However, there is variation in the results across cities within a state. This 

section will implement a more rigorous statistical approach to analyze the results at the 

city level: regression analysis using a Least Squares Dummy Variable (LSDV) model. 

6.4.1 Energy Use Savings across Cities 

As shown in Section 6.1.3, two primary drivers of variation in impacts are the energy 

code and climate zone of a city. Most cities are required to meet the building 

requirements of its state energy code, which vary for a given edition of ASHRAE 90.1

depending on the city’s climate zone. However, this does not explain all the variation in 

the percentage change in energy use across cities. For example, Figure 6-18 shows the 

average percentage change in energy use for each city in Texas considered in this study. 

For climate zones in Texas with multiple cities, there is variation in the percentage 

change in energy use. Consider the cities in Climate Zone 3B, where the variation in 

energy use savings is 2.8 percentage points (16.6 % to 19.4 %).

Figure 6-18 Average Percentage Change in Energy Use by City - Texas 

Since each climate zone is a bin of heating degree day (HDD) and cooling degree day 

(CDD) combinations (see ASHRAE 90.1 Standard), a city’s local climate could vary 
54

significantly from other cities’ climates even if they are located in the same climate zone. 

For example, there are five cities in the BIRDS database located in Climate Zone 3B 

within the state of Texas. Across these five cities, heating varies up to 907 degree days 

and cooling varies by 606 degree days, which is 35.1 % and 26.6 % of the median city’s 

degree days, respectively. These results are shown in Table 6-18. 

Table 6-18 Variation in Energy Use, Heating Degree Days, and Cooling Degree 

Days for Cities located in Climate Zone 3B in Texas 

Cities Climate 

Subzone

Low Energy Case

Percentage Change 

in Energy Use

Cooling 

Degree Days*

Heating 

Degree Days*

Abilene 3B -18.1 2410 2558

El Paso 3B -19.4 2331 2473

Lubbock 3B -16.6 1804 3380

Midland 3B -18.0 2278 2673

San Angelo 3B -17.8 2269 2582

Variation 2.8 606 907

Variation from Median City 15.6 % 26.6 % 35.1 %

*Base 18.3 °C (65 °F)

In order to determine the impact of this variation in HDDs and CDDs across cities, it is 

necessary to use regression analysis. An LSDV model is used to estimate the impact of a 

city’s HDDs and CDDs on the percentage change in energy use realized from adoption of 

the LEC design while controlling for a city’s energy code-climate zone combination. An 

interaction of the standard edition adopted and climate zone of a city is included in the 

model because the impact of each standard edition could vary across climate zones due to 

the different building requirements in each zone. 

The LSDV model is defined as: 

 

 

 

Where ENERGY USE CHANGE = percentage change in energy use from LEC design adoption 

STDk = binary variables indicating the energy standard edition that a city must meet in 

building construction 

ZONEh = binary variables indicating the ASHRAE climate zone in which a city is located 

HDD65 = number of heating degree days at base 18.3 °C (65°F) for a city 

CDD65 = number of cooling degree days at base 18.3 °C (65°F) for a city 

HDD65SQ = HDD65 squared 

CDD65SQ = CDD65 squared 
55

k = {1999, 2001, 2004, 2007} 

h = {1,2,3,4,5,6,7,8} 

i = index for cities used in analysis 

The marginal effect (impact) of variable xi is the change in ENERGY USE CHANGE as 

a result of changing variable xi holding all other variable values constant 

(

 

 

 ).

Seven of the potential 32 energy code-climate zone combinations nationwide are 

excluded from the model because not all energy standard editions are adopted for each 

climate zone. For example, ASHRAE 90.1-2001 is only adopted in three states, which 

span four climate zones. Of the 25 energy code-climate zone interaction variables shown 

in Table 6-19, only 24 have coefficient values because the 25th coefficient value is 

contained in the constant coefficient as a result of variable multicollinearity (the dummy 

variable trap), and is the baseline against which the other 24 coefficients are compared. In 

this model STD2004*ZONE1 is the baseline. 

The 25 energy code-climate zone interaction variable coefficients estimate the impact a 

city’s baseline energy code has on ENERGY USE CHANGE by adopting the LEC 

design. The coefficients on the STD1999 and STD2001 interaction variables are all 

negative and statistically significant. Relative to cities that build to meet ASHRAE 

90.1-2004 located in Zone 1, cities that build to meet ASHRAE 90.1-1999 and -2001

decrease the percentage change in energy use by 11.5 to 17.4 percentage points and 

10.4 to 11.6 percentage points, respectively, depending on the climate zone. Only two of 

the STD2004 interaction variable coefficients are statistically significant and decrease the 

percentage change in energy use (6.2 percentage points in Zone 2 and 12.9 percentage 

points in Zone 7). None of the STD2007 interaction variables are statistically significant. 

Based on these results, the older the edition of ASHRAE 90.1 to which a city must build,

the greater the percentage decrease in energy use. Additionally, the climate zone in which 

a city is located impacts the magnitude of the decrease. Both of these results reiterate the 

previous interpretations in this report. 
56

Table 6-19 Regression Analysis – Percentage Change in Energy Use from Adopting 

the LEC Design by City 

ENERGY USE CHANGE

Variables Coefficient

HDD65 0.00177***

HDD65SQ -1.52e-09

CDD65 0.00185**

CDD65SQ -3.45e-07

STD1999 * ZONE2 -17.36***

STD1999 * ZONE3 -15.26***

STD1999 * ZONE4 -12.89***

STD1999 * ZONE5 -13.72***

STD1999 * ZONE6 -11.47***

STD1999 * ZONE7 -14.08***

STD1999 * ZONE8 -12.65**

STD2001 * ZONE3 -10.40***

STD2001 * ZONE4 -11.57***

STD2001 * ZONE5 -11.54***

STD2001 * ZONE6 -10.85***

STD2004 * ZONE1

STD2004 * ZONE2 -6.246**

STD2004 * ZONE3 -1.046

STD2004 * ZONE4 -3.626

STD2004 * ZONE5 -4.882

STD2004 * ZONE6 -6.198

STD2004 * ZONE7 -12.90***

STD2007 * ZONE1 2.111

STD2007 * ZONE2 1.903

STD2007 * ZONE3 -0.113

STD2007 * ZONE4 1.010

STD2007 * ZONE5 -0.501

STD2007 * ZONE6 -2.692

STD2007 * ZONE7 -1.796

CONSTANT -24.83***

Observations 228

Adj. R-squared 0.785

Bolded coefficients are statistically 

significant at the following:

*** p<0.01, ** p<0.05, * p<0.1

Four variables are included in the model to control for local climate. Two of the variables 

are the total HDDs at base 18.3 °C (65°F) (HDD65) and total CDDs at base 18.3 °C 

(65°F) (CDD65) for a city. Additionally, two higher ordered terms (HDD65SQ and 
57

CDD65SQ) are included in the model to control for potential non-linear impacts of 

heating and cooling degree days. The coefficients for HDD65 and CDD65 are positive 

and statistically significant, with a two standard deviation increase in HDD65 (5358) and 

CDD65 (2066) leading to a 9.3 percentage point increase and 3.8 percentage point 

increase in the percentage change in energy use, respectively. The coefficient for 

HDD65SQ is statistically insignificant, and the coefficient for CDD65SQ is negative and 

nearly significant at the 10 % level.21

Consider the example of the five cities in Climate Zone 3B in Texas. Based on the 

coefficients for the four HDD and CDD variables and the HDD and CDD values for 

Lubbock and El Paso, the model predicts that El Paso’s energy use change should be 1.4 

percentage points lower than in Lubbock, which is half the observed variation.22 The 

squared partial correlation for the HDD and CDD variables (HDD65, CDD65, 

HDD65SQ, and CDD65SQ), which is the proportion of variance in the dependent 

variable (ENERGY USE CHANGE) not associated with any other explanatory variables 

in the model that is explained by the HDD and CDD variables, is 10.6 %. The model 

appears to explain a significant portion (two-thirds) of the observed variation in 

ENERGY USE CHANGE for the cities in Climate Zone 3B in Texas (15.6 %). 

6.4.2 Life-Cycle Cost Savings across Cities 

Similar to energy use, the energy code and climate zone are important factors in 

determining the percentage change in life-cycle costs for a city. Additionally, the 

state-level energy prices for a city will drive variation across states. However, there is 

some variation across cities within the same energy code-climate zone combination 

because local construction costs vary across cities as measured by the city construction 

cost index discussed in Section 3.1. Consider the same five cities in Climate Zone 3B in 

Texas discussed in the previous Section 6.4.1. Table 6-20 shows that the percentage 

change in life-cycle costs and the city construction cost index varies across cities, 

although to a lesser extent than do heating degree days and cooling degree days for 

energy use. 

 

21 Non-linearity in the degree day variables was suspected because when cities building to meet ASHRAE 

90.1-2007 were excluded from the regression, CDD65 became statistically significant in the model. 

22 The model predicts a nationwide average impact for a variable, which means that the predicted impact 

will not necessarily match the observed impact for the comparison of two specific data points. 
58

Table 6-20 Regression Analysis, Within State Variation in Life-Cycle Costs 

Cities Climate 

Subzone

Low Energy Case

Percentage Change 

in Life-cycle Costs

City Construction 

Cost Index

Abilene 3B -1.3 0.783

El Paso 3B -1.4 0.775

Lubbock 3B -1.3 0.795

Midland 3B -1.4 0.779

San Angelo 3B -1.4 0.757

Max – Min 0.1 0.038

Variation from Median City 7 % 5 %

Similar to the model estimating energy use, an LSDV model is used to estimate the 

impact of a city’s local construction cost index value on the percentage change in 

life-cycle costs while controlling for a city’s energy code-climate zone combination and 

state-level energy prices. An interaction of the standard edition adopted and climate zone 

of a city is included in the model because the impact of each standard edition could vary 

across climate zones due to the different building requirements in each zone. 

The LSDV model is defined as: 

 

 

Where LCC CHANGE = percentage change in life-cycle costs from LEC design adoption 

STDk = binary variables indicating the energy standard edition that a city must meet in 

building construction 

ZONEh = binary variables indicating the ASHRAE climate zone in which a city is located 

ELECT PRICE = state average electricity price 

GAS PRICE = state average natural gas price 

CITY COST INDEX = local city construction cost index 

k = {1999, 2001, 2004, 2007} 

h = {1,2,3,4,5,6,7,8} 

i = index for cities used in analysis

The marginal effect (impact) of variable xi is the change in LCC CHANGE as a result of 

changing variable xi holding all other variable values constant (

 

 

 ).

Seven of the potential 32 energy code-climate zone combinations nationwide are 

excluded from the model because not all energy standard editions are adopted for each 

climate zone. For example, ASHRAE 90.1-2001 is only adopted in three states, which 

span four climate zones. Of the 25 energy code-climate zone interaction variables shown 
59

in Table 6-21, only 24 have coefficient values because the 25th coefficient value is 

contained in the constant coefficient as a result of variable multicollinearity (the dummy 

variable trap), and is the baseline against which the other 24 coefficients are compared. In 

this model STD2007*ZONE7 is the baseline. 

The 25 energy code-climate zone interaction variable coefficients estimate the impact a 

city’s baseline energy code has on LCC CHANGE. The coefficients on the STD2001 

interaction variables are negative and statistically significant. Four, three, and one 

coefficient for the STD2004, STD1999, and STD2007 interaction variables are negative 

and statistically significant. Cities building to meet ASHRAE 90.1-2001 realize greater 

additional percentage point reductions (2.0 to 2.8) in life-cycle costs relative to cities 

building to meet ASHRAE 90.1-1999 (0.0 to 1.7), ASHRAE 90.1-2004 (0.0 to 2.2), and 

ASHRAE 90.1-2007 (0.0 to 1.0). The magnitude of the impacts varies depending on the 

climate zone of the city. 

The coefficient on a state’s electricity price (ELECT PRICE) is statistically significant 

while the coefficient on natural gas price (GAS PRICE) is statistically insignificant. A 

greater electricity price leads to lower life-cycle costs, with a two standard deviation in 

electricity price (5.3¢/kWh) decreasing life-cycle costs by 0.9 percentage points. The 

squared partial correlation for ELECT PRICE, which is the proportion of variance in the 

dependent variable (LCC CHANGE) not associated with any other explanatory variables 

in the model that is explained by ELECT PRICE, is greater than any other variable in the 

model at 47.3 %. There is a strong correlation between a city’s average electricity price 

and its percentage change in life-cycle costs realized from adoption of the LEC design. 
60

Table 6-21 Regression Analysis – Percentage Change in Life-cycle Costs from 

Adopting the LEC Design by City 

LCC CHANGE

Variables Coefficient

Elect Price -16.62***

Gas Price 6.490

City Cost Index 1.824***

STD1999 * ZONE2 -1.698***

STD1999 * ZONE3 -0.714***

STD1999 * ZONE4 0.102

STD1999 * ZONE5 -0.598*

STD1999 * ZONE6 -0.0128

STD1999 * ZONE7 -0.0910

STD1999 * ZONE8 0.436

STD2001 * ZONE3 -2.752***

STD2001 * ZONE4 -2.048***

STD2001 * ZONE5 -2.349***

STD2001 * ZONE6 -2.198***

STD2004 * ZONE1 -2.172***

STD2004 * ZONE2 -1.971***

STD2004 * ZONE3 -0.261

STD2004 * ZONE4 -0.604**

STD2004 * ZONE5 -0.816**

STD2004 * ZONE6 -0.458

STD2004 * ZONE7 -0.503

STD2007 * ZONE1 -1.009***

STD2007 * ZONE2 -0.168

STD2007 * ZONE3 -0.134

STD2007 * ZONE4 -0.238

STD2007 * ZONE5 -0.0394

STD2007 * ZONE6 0.0868

STD2007 * ZONE7

Constant -1.052***

Observations 228

Adj. R-squared 0.813

Bolded coefficients are statistically 

significant at the following:

*** p<0.01, ** p<0.05, * p<0.1

The coefficient for the local city construction cost index (CITY COST INDEX) is 

statistically significant, with a two standard deviation in the index (0.21) leading to a 0.4 

percentage point increase in life-cycle costs. The more expensive it is to construct a 

building, the smaller the decrease in life-cycle costs. Once again consider the example of 

the five cities in Climate Zone 3B in Texas. Based on the regression results, the variation 

in the city construction cost index (0.038) leads to a predicted variation of 0.07 
61

percentage points in the change in life-cycle costs, or 70 % of the observed variation.23

The squared partial correlation for CITY COST INDEX, which is the proportion of 

variance in the dependent variable (LCC CHANGE) not associated with any other 

explanatory variables in the model that is explained by the CITY COST INDEX, is 

14.8 % compared to the 7 % observed variation in LCC CHANGE for the cities in 

Climate Zone 3B in Texas. The city construction cost index accounts for more than 

enough variation in the model to explain the observed variation in the percentage change 

in life-cycle costs for cities located Zone 3B in Texas.

 

23 The percentage change data have been rounded to one decimal, which leads to some uncertainty as to the 

impact explained by the city cost index. Also, the model predicts a nationwide average impact for a 

variable, which means that the predicted impact will not necessarily match the observed impact for the 

comparison of two specific data points. 
62
63

7 Nationwide Impacts of Adopting ASHRAE 90.1-2007

This section analyzes benefits from nationwide adoption of the ASHRAE 90.1-2007

design relative to the current collection of state energy codes. Benefits are evaluated 

across several dimensions: time, building type, geography (climate zone and state), and 

energy code. There are three metrics used to analyze the results: percentage changes, total 

changes, and changes per unit of floor area. The analysis only includes states that have 

not yet adopted ASHRAE 90.1-2007.

7.1 Percentage Changes 

The initial metrics used to estimate the impacts of adopting the ASHRAE 90.1-2007

design are the average percentage changes in energy use, energy costs, carbon emissions, 

and life-cycle costs. Impacts are evaluated across four dimensions: study period length, 

building type, climate zone, and state energy code.

7.1.1 Results by Study Period Length 

It is important to consider how the study period length – representing the time horizon of 

the investor -- impacts energy use, energy costs, energy-related carbon emissions, and 

life-cycle costs. Nine study periods are analyzed: 1 year, 5 years, 10 years, 15 years, 20 

years, 25 years, 30 years, 35 years, and 40 years.

The average reduction in energy use from adoption of ASHRAE 90.1-2007 is constant 

over all study period lengths because energy efficiency is assumed to be constant over 

time. Table 7-1 shows that the national average change in energy use across the 73 cities 

in the analysis ranges from -15.6 % to 0.5 %, depending on the building type, with an 

overall national average of -9.6 %. The 16-story office building realizes a percentage 

increase in energy use because the relaxation of the window requirements overwhelms 

the impacts from the other energy efficiency measures required by ASHRAE 90.1-2007.
64

Table 7-1 Nationwide Average Percentage Change in Energy Use from Adoption of 

ASHRAE 90.1-2007 by Building Type 

Building 

Type

Percentage 

Change

APART04 -11.4

APART06 -11.0

DORMI04 -12.3

DORMI06 -10.7

HOTEL15 -3.2

HIGHS02 -5.8

OFFIC03 -11.4

OFFIC08 -9.8

OFFIC16 0.5

RETAIL1 -15.2

RSTRNT1 -15.6

Average -9.6

As shown in Table 7-2, savings in energy costs vary slightly, in percentage terms, over 

increasing study period lengths. The national average change in energy costs across all 

location-building type combinations ranges from -12.3 % to -12.0 % for all study period 

lengths. There is minor variation of up to 0.6 percentage points for some building types 

across study periods as a result of the escalation rates used to adjust future energy prices, 

which vary by U.S. Census Region.

Table 7-2 Nationwide Average Percentage Change in Energy Costs from Adoption 

of ASHRAE 90.1-2007 by Building Type and Study Period Length 

Building 

Type

Study Period Length

1 5 10 15 20 25 30 35 40

APART04 -16.9 -16.7 -16.7 -16.6 -16.5 -16.4 -16.3 -16.3 -16.3

APART06 -16.6 -16.4 -16.3 -16.2 -16.2 -16.1 -16.0 -16.0 -16.0

DORMI04 -17.4 -17.3 -17.2 -17.1 -17.1 -17.0 -16.9 -16.9 -16.9

DORMI06 -16.5 -16.4 -16.3 -16.2 -16.1 -16.0 -16.0 -16.0 -16.0

HOTEL15 -8.3 -8.2 -8.1 -8.0 -8.0 -7.9 -7.8 -7.8 -7.8

HIGHS02 -7.8 -7.7 -7.7 -7.7 -7.6 -7.6 -7.6 -7.6 -7.6

OFFIC03 -10.6 -10.6 -10.6 -10.6 -10.6 -10.7 -10.7 -10.7 -10.7

OFFIC08 -9.5 -9.5 -9.5 -9.5 -9.5 -9.5 -9.5 -9.5 -9.5

OFFIC16 -0.9 -0.8 -0.8 -0.8 -0.8 -0.8 -0.7 -0.7 -0.7

RETAIL1 -15.1 -15.1 -15.1 -15.1 -15.1 -15.1 -15.1 -15.1 -15.1

RSTRNT1 -15.5 -15.5 -15.5 -15.5 -15.5 -15.5 -15.5 -15.5 -15.5

Average -12.3 -12.2 -12.2 -12.1 -12.1 -12.1 -12.0 -12.0 -12.0

Since the national average reduction in energy use across all location-building type 

combinations is constant over all study period lengths, the average change in 

energy-related carbon emissions is also constant at -15.6 %. The national average change 

in carbon emissions ranges from -17.9 % to -0.9 % depending on the building type, as 

shown in Table 7-3. 
65

Table 7-3 Nationwide Average Percentage Change in Carbon Emissions from 

Adoption of ASHRAE 90.1-2007 by Building Type 

Building 

Type

Percentage 

Change

APART04 -17.4

APART06 -17.1

DORMI04 -17.9

DORMI06 -17.1

HOTEL15 -8.8

HIGHS02 -8.2

OFFIC03 -10.5

OFFIC08 -9.3

OFFIC16 -0.9

RETAIL1 -15.0

RSTRNT1 -15.6

Average -12.4

Table 7-4 shows that the percentage change in life-cycle costs varies slightly over 

increasing study period lengths, with the average change across all location-building type 

combinations ranging from -1.9 % for a 1-year study period to -0.7 % for a 10-year study 

period. The national average change in life-cycle costs ranges from -6.7 % to 2.3 % 

depending on the building type for a 1-year study period. The nationwide change in lifecycle costs averages -0.7 % for a 10-year study period length, ranging from -1.7 % to 

0.5 % depending on the building type. As the study period length increases from 10 years 

to 40 years, the percentage reduction in national average life-cycle costs increases, with 

an overall average percentage change of -0.7 % to -1.1 %, respectively. Also, the number 

of building types that realize reductions in life-cycle costs increases from 7 for a 20-year 

study period to 10 for a 40-year study period. 

Table 7-4 National Average Percentage Change in Life-Cycle Costs from Adoption 

of ASHRAE 90.1-2007 by Building Type and Study Period Length 

Building 

Type

Study Period Length

1 5 10 15 20 25 30 35 40

APART04 -1.8 -1.8 -1.7 -1.8 -1.9 -1.9 -1.9 -2.0 -2.0

APART06 -1.1 -1.6 -1.6 -1.8 -1.8 -1.9 -1.9 -2.0 -2.0

DORMI04 -4.1 -1.1 -0.9 -1.0 -1.1 -1.2 -1.2 -1.3 -1.4

DORMI06 -2.1 -2.1 -2.0 -2.1 -2.1 -2.2 -2.2 -2.3 -2.3

HOTEL15 -1.4 -1.3 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2

HIGHS02 -1.4 -0.8 -0.8 -0.9 -0.9 -1.0 -1.1 -1.1 -1.1

OFFIC03 -3.1 0.4 0.5 0.3 0.2 0.1 0.1 0.0 -0.1

OFFIC08 0.2 0.6 0.5 0.3 0.1 -0.0 -0.0 -0.1 -0.2

OFFIC16 -1.5 -0.3 -0.1 0.1 0.1 0.2 0.2 0.2 0.3

RETAIL1 -6.7 -1.2 -0.9 -1.1 -1.2 -1.3 -1.4 -1.4 -1.5

RSTRNT1 2.3 0.8 0.4 0.0 -0.2 -0.4 -0.5 -0.6 -0.7

Average -1.9 -0.8 -0.7 -0.8 -0.9 -1.0 -1.0 -1.1 -1.1
66

7.1.2 Results by Building Type 

Table 7-5 shows the simple average changes, in percentage terms, from adopting

ASHRAE 90.1-2007 by building type for a 10-year study period length. The tallest 

buildings realize the lowest reductions in energy use. The only building type that realizes 

an increase in energy use is the 16-story office building. The hotel and high school realize 

reductions in energy use of 3.2 % and 5.8 %, respectively. The remaining building types 

all realize reductions in energy use greater than 9.8 %. All building types realize 

reductions in energy costs, ranging from 0.8 % to 17.2 %. The 16-story office building 

realizes small reductions in energy costs even though its energy use increases because 

energy use is shifted from electricity to natural gas. The apartments and dormitories 

realize the greatest reductions in energy costs. All building types realize reductions in 

energy-related carbon emissions, ranging from 0.9 % to 17.9 %. The greatest reductions 

in carbon emissions are realized by the apartment buildings and dormitories at over 

15.0 % while the smallest reductions are realized by the 16-story office building. Of the 

11 building types, 8 realize a decrease in life-cycle costs. The greatest reductions in 

life-cycle costs are realized by the 6-story dormitory (2.0 %) and 4-story apartment 

building (1.7 %). The greatest life-cycle cost increases are realized by the 3-and 8-story 

office buildings (0.5 % each) and the restaurant (0.4 %).

Table 7-5 Nationwide Percentage Change for ASHRAE 90.1-2007 by Building Type, 

10-Year 

Building 

Type

Percentage Change

Energy Use Energy Cost Carbon LCC

APART04 -11.4 -16.7 -17.4 -1.7

APART06 -11.0 -16.3 -17.1 -1.6

DORMI04 -12.3 -17.2 -17.9 -0.9

DORMI06 -10.7 -16.3 -17.1 -2.0

HOTEL15 -3.2 -8.1 -8.8 -1.2

HIGHS02 -5.8 -7.7 -8.2 -0.8

OFFIC03 -11.4 -10.6 -10.5 0.5

OFFIC08 -9.8 -9.5 -9.3 0.5

OFFIC16 0.5 -0.8 -0.9 -0.1

RETAIL1 -15.2 -15.1 -15.0 -0.9

RSTRNT1 -15.6 -15.5 -15.6 0.4

Average -9.6 -12.2 -12.4 -0.7

Overall, the buildings with the greatest window-to-wall ratios realize the lowest 

reductions, or even increases, in energy use, energy costs, and carbon emissions while the 

residential buildings (apartments and dormitories), retail stores, and restaurants realize 

the greatest reductions. 
67

7.1.3 Results by Climate Zone 

Table 7-6 shows the nationwide average change in energy use by ASHRAE climate zone 

for the adoption of ASHRAE 90.1-2007 relative to current state energy codes for all 

building types. The warmest and coldest climate zones, Zone 1 and Zone 8, realize the 

smallest overall percentage changes in energy use. Zone 8 realizes an increase of energy 

use of 1.7 % while Zone 1 realizes a small decrease of 1.1 %. Zone 2 realizes the highest 

reductions in energy use at 16.3 % followed by Zone 3 (12.0 %) and Zone 4 (10.4 %). 

Table 7-6 Average Percentage Change in Energy Use for ASHRAE 90.1-2007 by 

Climate Zone 

Climate 

Zone/Subzone

Percentage Change

1999 2001 2004 All

1 -1.1 -1.1

2 -24.0 -8.6 -16.3

A -23.9 -23.9

B -24.2 -8.6 -13.8

3 -19.6 -13.8 -1.9 -12.0

A -19.6 -13.8 -1.7 -12.7

B -2.7 -2.7

4 -14.0 -12.9 -2.5 -10.4

A -13.6 -12.9 -2.5 -10.0

B -16.1 -16.1

5 -14.5 -12.3 -3.5 -7.9

A -12.7 -11.2 -11.9

B -16.2 -12.7 -3.5 -7.2

6 -11.2 -10.3 -4.4 -9.7

A -10.6 -9.6 -4.4 -8.2

B -11.7 -10.7 -11.4

7 -10.5 -7.4 -9.7

8 1.7 1.7

Grand Total -12.9 -12.3 -3.7 -9.6

Similar to the LEC design, the current state energy codes are a key driver of these results. 

The variation across climate zones diverges depending on the state energy code. For 

locations in states that have not adopted any state energy code or have adopted older 

editions of ASHRAE 90.1 (-1999 or -2001), warmer climate zones realize greater 

percentage reductions in energy use. For states that have no state energy code or have 

adopted ASHRAE 90.1-1999, cities in Zone 2 realize an average percentage reduction of 

24.0 % while Zone 8 realizes an increase of 1.7 % from adopting the ASHRAE 90.1-2007

design. For cities located in states that have adopted ASHRAE 90.1-2004, the percentage 
68

reductions in energy use are much smaller, ranging from 1.1 % to 8.6 %, and do not 

follow the same trend where colder climate zones realize smaller reductions in energy 

use. Instead the percentage changes are the greatest for cities in Zone 2 followed by Zone 

7 and smallest for cities in Zone 1 and Zone 3. 

Table 7-7 shows that the average reduction in energy costs over a 10-year study period 

ranges from 1.1 % to 15.2 % depending on the climate zone. Zone 2, Zone 3, Zone 6, and 

Zone 7 realize reductions in energy costs over 13 %. Zone 1 realizes reductions in energy 

costs of only 1.1 %. The reductions in energy costs for Zone 8 of 10.2 % could be 

considered surprising given that Zone 8 realizes an increase in energy use. 

Table 7-7 Average Percentage Change in Energy Costs for ASHRAE 90.1-2007 by 

Climate Zone, 10-Year 

Climate 

Zone/Subzone

Percentage Change

1999 2001 2004 All

1 -1.1 -1.1

2 -24.1 -6.4 -15.2

A -24.1 -24.1

B -24.1 -6.4 -12.3

3 -21.5 -18.1 -2.9 -14.1

A -21.5 -18.1 -2.7 -14.9

B -3.7 -3.7

4 -17.1 -14.7 -0.9 -11.9

A -16.7 -14.7 -0.9 -11.4

B -19.1 -19.1

5 -18.0 -16.4 -1.4 -8.6

A -17.0 -13.0 -15.0

B -19.0 -17.6 -1.4 -7.4

6 -16.6 -17.1 -1.9 -13.8

A -15.9 -14.7 -1.9 -10.5

B -17.1 -18.4 -17.5

7 -16.5 -4.2 -13.4

8 -9.8 -9.8

Grand Total -17.4 -16.6 -2.3 -12.1

These results are similar to those realized for reductions in energy use in that they can be 

better explained after controlling for the current state energy codes. Reductions in energy 

use can explain some, but not all of the variation in energy costs. The remainder is a 

result of a shift in energy use from one energy source to another. For example, the 

adoption of ASHRAE 90.1-2007 leads to a percentage change in energy use of -24.0 % 

and 1.7 % for cities in Zone 2 and Zone 8, respectively. Meanwhile, the percentage 

change in energy costs is -24.1 % and -9.8 %, respectively. The percentage change in 
69

energy use explains the entire percentage change in energy costs for cities in Zone 2. 

However, cities in Zone 8 realize a percentage increase in energy use and a seemingly 

contradictory decrease in energy costs. The adoption of ASHRAE 90.1-2007 decreases 

electricity consumption, but increases natural gas consumption by a greater amount. Due 

to the higher cost of electricity for cities in Zone 8, energy use is increased while energy 

costs are decreased. Similar shifts occur for cities throughout the other climate zones, 

where the size of the impact depends on the size of the fuel shift and the differential 

between the average cost of electricity and average cost of natural gas. 

Average energy-related carbon emissions are constant across study period lengths. The 

data reported in Table 7-8 show that the average reduction in energy-related carbon 

emissions for the ASHRAE 90.1-2007 design ranges from 1.2 % to 15.3 % depending on 

the climate zone. Zone 1, Zone 8, and Zone 5 realize the smallest percentage reductions 

in carbon emissions while Zone 2 and Zone 3 realize the greatest reductions. Similar to 

reductions in energy costs, reductions in energy use can explain some, but not all of the 

variation in the reductions in carbon emissions. The remainder is a result of a shift in 

energy use from one energy source to another. For example, the adoption of ASHRAE 

90.1-2007 leads to a percentage change in energy use of 1.7 % and a percentage change 

in carbon emissions of -5.8 % for cities in Zone 8. For Alaska, the average carbon 

emissions rate for electricity is greater than the average carbon emissions rate for natural 

gas. The shift in energy use from electricity to natural gas leads to an overall decrease in 

carbon emissions while total energy use increases. 
70

Table 7-8 Average Change in Energy-related Carbon Emissions for ASHRAE 

90.1-2007 by Climate Zone 

Climate 

Zone/Subzone

Percentage Change

1999 2001 2004 All

1 -1.2 -1.2

2 -24.0 -6.5 -15.3

A -23.8 -23.8

B -24.1 -6.5 -12.4

3 -22.5 -19.7 -3.2 -15.0

A -22.5 -19.7 -3.0 -15.9

B -3.7 -3.7

4 -18.3 -16.9 -1.0 -13.1

A -18.1 -16.9 -1.0 -12.5

B -19.6 -19.6

5 -18.9 -17.7 -2.1 -9.5

A -18.3 -16.8 -17.5

B -19.5 -18.0 -2.1 -8.0

6 -16.6 -17.9 -1.9 -14.0

A -16.3 -15.3 -1.9 -10.8

B -17.0 -19.2 -17.6

7 -15.6 -3.9 -12.7

8 -5.8 -5.8

Grand Total -17.4 -18.0 -2.5 -12.4

7.1.4 Results by State Energy Code 

One purpose of this study is to determine which states could benefit the most from 

adopting a more stringent state energy code for commercial buildings. It would be 

expected that states with energy codes based on an older edition of ASHRAE 90.1 

(-2001), or no energy code at all, would realize greater benefits from adopting the 

ASHRAE 90.1-2007 design because buildings in those states are expected to be built in a 

less energy efficient manner. Figure 7-1 shows the 14 states with energy codes based on 

ASHRAE 90.1 -2001 or that have no state energy code.24

 

24 All maps are generated in ArcMap 10.1. 
71

Figure 7-1 States with Energy Code based on ASHRAE 90.1-2001 or No Energy 

Code

The 32 states that have adopted ASHRAE 90.1-2007, highlighted gray in Figure 7-2, are 

spread across the nation. These states are shown in white in the figures in this section, 

and are excluded from the analysis because there are no impacts to report. 

Figure 7-2 States with Energy Code based on ASHRAE 90.1-2007 (Shown in Gray)

As in the state-by-state analysis of the LEC design, analyzing benefits from adopting the 

ASHRAE 90.1-2007 design requires an assumption on the study period length because 

costs to maintain and operate a building fluctuate over time. A 10-year study period is 

used as a baseline because it is one of the most realistic investor time frames of the 9 

study period length options in BIRDS.

State benefit comparisons are made based on the simple average changes for the cities 

analyzed in each state by building type. One building type is chosen to illustrate the 

detailed analysis possible with the powerful BIRDS database compiled for this study. 

Energy use, energy costs, cradle-to-grave energy-related carbon emissions, and life-cycle 

costs are analyzed for the most common existing building type, small office buildings. 

Summary results for the other 10 building types are reported in Table D-1 through Table 

D-10 in Appendix D. The same interpretations hold for the other ten building types. 
72

Table 7-9 summarizes the percentage changes in energy use, energy costs, carbon 

emissions, and life-cycle costs for the 3-story office building for a 10-year study period. 

On average, adoption of ASHRAE 90.1-2007 for a 3-story office building decreases 

energy use, energy costs, and energy-related carbon emissions by over 10 % each while 

increasing life-cycle costs by 0.5 %, on average. These results exclude the states that 

have already adopted ASHRAE 90.1-2007. 

Table 7-9 Average Percentage Change by State, 3-Story Office Building, 10-Year 

State

Percentage Change

State

Percentage Change

Energy 

Use

Energy 

Cost

Carbon LCC Energy 

Use

Energy 

Cost

Carbon LCC

AK -8.0 -10.6 -9.7 0.9 MS -26.4 -21.1 -20.9 1.7

AL -19.0 -18.3 -17.9 1.2 ND -12.5 -12.9 -13.0 2.4

AR -12.2 -13.8 -14.3 -3.4 NV -5.7 -2.7 -3.5 -0.4

AZ -15.8 -14.1 -13.7 0.6 OK -13.8 -15.6 -16.8 2.6

CO -11.3 -10.9 -10.9 -2.6 SC -2.6 -2.4 -2.4 -0.6

HI -1.6 -1.6 -1.6 -0.3 SD -12.6 -12.8 -12.8 0.8

KS -15.0 -14.4 -14.3 3.3 TN -4.6 -2.6 -2.3 -0.4

ME -14.2 -13.8 -13.8 1.6 WV -13.5 -13.1 -12.1 -2.1

MN -9.2 -4.3 -3.8 -0.5 WY -13.3 -13.6 -13.6 2.2

MO -14.8 -14.2 -13.9 3.0 Avg. -11.4 -10.6 -10.5 0.5

Figure 7-3 overlays Figure 7-1 and displays the average percentage changes in energy 

use, energy costs, and carbon emissions for a 10-year study period by state. The states 

with codes based on older editions of ASHRAE 90.1, or no energy code at all, are shown 

with cross hatching and bolded state borders. The 31 states that have already adopted 

ASHRAE 90.1-2007 are shown in white and are excluded from the analysis. Figure 7-3

shows that 16 of 19 states realize energy use savings greater than 5 % by adopting 

ASHRAE 90.1-2007 over their current state energy code. Many of the states that realize 

the greatest energy use savings are the ones that currently have no energy code or energy 

codes based on older editions of ASHRAE 90.1 including all 13 states that realize energy 

use savings of more than 10 %.

The state average percentage reductions in energy costs and carbon emissions are highly 

correlated with the percentage reductions in energy use. However, the reduction in energy 

costs and carbon emissions tend to be slightly less than the reductions in energy use. 

Twelve of the nineteen states realize smaller percentage changes in energy costs and 

carbon emissions than percentage changes in energy use. The reason for this result is 

because the reductions in total energy use resulting from the adoption of ASHRAE 

90.1-2007 for those twelve states are driven primarily by reductions in natural gas, as 

discussed in the example in Section 6.1.4.1. Since natural gas is cheaper and has a lower 

average emissions rate than electricity for those states, the percentage changes in energy 

costs and carbon emissions are smaller than the percentage changes in energy use. 
73

Figure 7-3 Average Energy Use Savings by State, 3-Story Office Building, 10-Year 

For a 3-story office building, as expected, states that currently have no energy code or 

energy codes based on older editions of ASHRAE 90.1 have the most to gain in 

percentage terms in energy use, energy cost, and carbon emissions savings from adopting 

more stringent state energy codes. However, the life-cycle cost-effectiveness of such 

adoptions varies across states. 

Figure 7-4 overlays Figure 7-1 with the average percentage change in life-cycle costs 

over 10 years by state from adopting the ASHRAE 90.1-2007 design. Of the 19 states, 8 

realize an average decrease in life-cycle costs. The three states that have energy codes 
74

based on ASHRAE 90.1-2001 realize the greatest percentage decreases in life-cycle costs 

(> 2 %). The five states that have adopted ASHRAE 90.1-2004 as their state energy code 

realize reductions in life-cycle costs of less than 2 %. The ten states that currently have 

no energy code realize an average percentage increase in life-cycle costs, five of which 

realize an increase greater than 2 %. The additional energy efficiency measures required 

to bring buildings up to the ASHRAE 90.1-2007 design from the ASHRAE 90.1-1999

baseline design for these states add enough construction costs to offset the energy cost 

savings from the energy efficiency gains. 

Figure 7-4 Average Life-Cycle Cost Savings by State, 3-Story Office Building, 

10-Year 

7.2 Total Changes 

The average percentage changes in energy use, energy costs, energy-related carbon 

emissions, and life-cycle costs reported in Section 7.1 do not account for the amount of 

new floor area for each building type in a state, which may have a significant impact on 

the results. 

7.2.1 State-Level Total Savings 

Estimating the magnitude of the total impacts in a state controls for new floor area and 

determines which states would benefit the most from adopting the ASHRAE 90.1-2007

design as their state energy code. The total changes in the four impacts from adopting the 

ASHRAE 90.1-2007 design for a state are calculated using Formula 1 defined in Section 

5.4. Based on the formula, two variables impact the magnitude of the total changes in a 

state: the amount of new commercial building construction and the average changes per 

unit of floor area. 

Figure 7-5 shows the average amount of new floor area constructed annually (1000 m2

) 

for each of the 19 states from 2003 to 2007. States with a greater amount of new floor 

area constructed (Arizona, Colorado, Nevada, and Tennessee) are expected to realize 

greater total reductions in energy use, energy costs, and carbon emissions. 
75

Figure 7-5 Average Annual New Floor Area by State

Table E-1 in Appendix E shows the total changes in energy use, energy costs, carbon 

emissions, and life-cycle costs from adopting the ASHRAE 90.1-2007 design as the 

commercial building energy code for all 19 states for a 10-year study period. The relative 

total changes across states, shown in Figure 7-6, are significantly different than the 

relative percentage changes shown in Figure 7-3, which emphasizes the importance of 

controlling for the amount of new floor area for each building type in determining the 

magnitude of the impacts of adopting the ASHRAE 90.1-2007 design. The total change in 

energy use for a state is driven partially by the amount of new floor area constructed in a 

state. Arizona realizes the greatest reductions in energy use (946 GWh). In comparison, 

states with the smallest amount of new floor area (Alaska, Hawaii, Maine, North Dakota, 

South Dakota, and Wyoming) realize savings of less than 106 GWh. However, the state 

energy code is also a significant driver of the results. For example, Nevada, South 

Carolina, and Tennessee are in the top five in total new floor area, but are not in the top 

ten in total energy use savings. 
76

Figure 7-6 Total Energy Use, Energy Cost, and Carbon Emissions Savings by State, 

10-Year 

Figure 7-6 shows a correlation between total savings in energy use and total savings in 

energy costs and carbon emissions. Alabama, Arizona, Missouri, and Colorado realize 

the greatest savings while South Dakota, North Dakota, Wyoming, Nevada, Hawaii, 

Alaska, Maine, and South Carolina realize the smallest savings in energy costs. Arizona, 

Alabama, Colorado, Oklahoma, and Missouri realize the greatest reductions while South 

Dakota, North Dakota, Wyoming, and Nevada realize the smallest reductions in carbon 

emissions. The relative total reductions in energy costs and carbon emissions vary from 

total reductions in energy use to some extent. The reasons for this variation will be 

discussed in Section 7.3.
77

Figure 7-7 shows a correlation between total savings in energy use and total savings in 

life-cycle costs. Arizona, Colorado, Arkansas, and Alabama realize the greatest total 

life-cycle cost savings. Only two states realize an increase in life-cycle costs (Kansas and 

Oklahoma) while the other nine states that realize an increase in life-cycle costs on a 

percentage basis (see Figure 7-4) realize a total life-cycle cost decrease. These results 

emphasize the importance of accounting for the building types associated with the new 

floor area constructed in a state to determine where adopting the ASHRAE 90.1-2007

design is life-cycle cost-effective. The relative total reductions in life-cycle costs vary 

from total reductions in energy use to some extent. The reasons for this variation will be 

discussed in Section 7.3.

Figure 7-7 Total Life-Cycle Cost Savings by State, 10-Year 

7.2.2 Regional and National Total Savings 

The nationwide changes in the four impacts from adopting the ASHRAE 90.1-2007

design are calculated using Formula 2 defined in Section 5.4, where the state-level 

savings for each impact are summed across all nineteen states that have not yet adopted 

ASHRAE 90.1-2007. 

Table 7-10 shows the total changes in energy use, energy costs, energy-related carbon 

emissions, and life-cycle costs for one year’s worth of construction for a 10-year study 

period aggregated at the Census region and national levels. The greater the amount of 

new floor area constructed in the states within a Census region that have not yet adopted 

ASHRAE 90.1-2007, the greater the total reduction in energy use, energy costs, and 

carbon emissions. This condition does not strictly hold for the total reduction in life-cycle 

costs because the total reduction in the West Census Region is greater than total reduction 

in the South Census Region. The reason for this variation will be discussed in Section 

7.3. The nationwide reductions total 4.9 TWh in energy consumption, $312.4 million in 

energy costs, 3.8 million metric tons in energy-related carbon emissions, and 

$173.3 million in life-cycle costs for the 10-year study period. 
78

Table 7-10 Total Reductions by Census Region from Adoption of the ASHRAE 

90.1-2007 Design, 10-Year 

Census 

Region

Number

of

States

Average Annual New 

Floor Area

1000 m2(1000 ft2)

Energy 

Use 

(GWh)

Energy 

Costs 

($million)

Carbon 

(1000 tCO2e)

LCC 

($million)

Northeast 1 497 (5349) 105.5 9.4 58.8 3.3

Midwest 5 6296 (67 767) 1139.5 54.5 867.1 7.7

South 7 12 750 (137 243) 1968.2 139.4 1707.2 67.4

West 6 12 622 (135 861) 1667.6 109.1 1183.4 94.9

Total 19 32 165 (346 220) 4880.8 312.4 3816.5 173.3

7.3 Changes per Unit of Floor Area and Energy Use Savings 

Total savings in energy use, energy costs, carbon emissions, and life-cycle costs are 

correlated. However, there are a number of factors that lead to significant variation in 

relative savings, each of which will be discussed in this section. 

7.3.1 State Level Changes 

There is significant variation in relative savings across states for each of the four impacts 

for a number of reasons, including current state energy code requirements, newly 

constructed building stock mix and size, climate zone, electricity costs, electricity 

production fuel mix (average emissions rate), and the relative percentage changes in fuel 

types consumed by the building. 

7.3.1.1 Energy Use Savings per Unit of Floor Area 

Total energy use savings varies across states for a number of reasons. First, states with 

more newly constructed commercial floor area realize greater reductions in energy use. 

Second, states located in warmer climate zones tend to realize greater reductions in 

energy use than the states located in colder climate zones. Third, a state’s current state 

energy code for commercial buildings drives variation in energy use. 

Table E-2 shows the 10-year reduction in energy use per unit of newly constructed floor 

area sorted by energy savings per unit of new floor area in descending order. The 

reduction in energy use per unit of floor area is primarily driven by the state’s adopted 

energy code for commercial buildings. The top thirteen states with the greatest per unit 

reduction from adoption of the ASHRAE 90.1-2007 design have no state energy code or 

have ASHRAE 90.1-2001 as their state energy code. These results, shown in Figure 7-8, 

can be compared to the average percentage changes in energy use in Figure 7-3. After 

controlling for the amount of new floor area, the relative savings across states correlates 

much closer to the relative average percentage changes in energy use. However, the 
79

correlation is not perfect because the total changes weight building types based on new 

floor area constructed. 

Figure 7-8 Energy Use Savings per Unit of Floor Area by State, 10-Year 

7.3.1.2 Life-Cycle Cost Savings per Unit of Floor Area 

The relative change in life-cycle costs per unit of new floor area is shown in Table E-3. 

After controlling for the amount of new floor area, there is a correlation between the state 

energy code and the relative life-cycle cost savings of adopting the ASHRAE 90.1-2007

design. States that have adopted ASHRAE 90.1-2001 (Arkansas, Colorado, and West 

Virginia) realize the greatest life-cycle cost savings. These results, shown in Figure 7-9, 

can be compared to the average percentage changes in life-cycle costs in Figure 7-4. 

After controlling for the amount of new floor area, the relative savings across states 

correlates better with the relative percentage changes in energy use. However, the 

correlation is not perfect because the total changes weight building types based on new 

floor area constructed. 

Figure 7-9 Life-Cycle Cost Savings per Unit of Floor Area by State, 10-Yr

7.3.1.3 Energy Cost Savings per Unit of Energy Use Savings 

In general, the states that realize the greatest reductions in energy use also realize the 

greatest reductions in energy costs. However, reductions in energy costs are also 
80

impacted by the per unit costs of electricity and natural gas and the fuel mix of the 

reductions in total energy use in a state. Table E-4 shows each state’s reduction in energy 

costs per unit of reduction in energy use, natural gas rate, electricity rate, and the fraction 

of electricity consumption reductions offset by increases in natural gas consumption.25

States with the highest electricity rates tend to realize the greatest reductions in energy 

costs per unit of reduction in energy use. Relative to electricity prices, natural gas has 

minimal impacts on the relative reduction because natural gas prices are fairly constant 

across states (excluding Hawaii) and are significantly cheaper per unit of energy for all 

nineteen states. 

The correlation between a state’s average electricity price and the savings in energy costs 

per unit of energy use savings is shown in Figure 7-10. States with the highest electricity 

prices (Alaska, Hawaii, and Maine) realize the greatest savings in energy costs per unit of 

savings in energy use. 

Figure 7-10 Energy Cost Savings per Unit of Energy Use Savings and Average 

Electricity Price by State 

 

25 The fraction of electricity offset by natural gas consumption is greater than 100 % when natural gas 

consumption increases by a greater amount than electricity consumption decreases. The fraction of 

electricity offset by natural gas consumption is less than -100 % when natural gas consumption increases 

(decreases) by a greater amount than electricity consumption decreases. For some states (e.g. Minnesota) 

the magnitude of the offset is large because the change in electricity is minimal, leading to the change in 

natural gas to be large in comparison on a percentage change basis. 
81

The electricity price does not explain all the variation across states in energy cost savings 

per unit of energy use savings because there are two sources of energy cost savings: the 

energy costs savings from total energy use reduction, and the energy cost savings from 

the shift of fuel consumption from more expensive electricity to cheaper natural gas. The 

savings from the shift in fuels is a result of two factors: the energy cost savings per unit 

of energy shifted from electricity to natural gas consumption (energy price differential) 

and the amount of energy shifted from electricity to natural gas consumption. The energy 

cost savings increases as the energy price differential increases because the cost savings 

for each unit of electricity “offset” by a unit of natural gas is greater. The greater the 

fraction of electricity consumption shifted to natural gas consumption, or offset, the 

greater the energy cost savings per unit of total energy use savings. 

The metric used to explain the shift in fuel consumption is the “weighted average offset,” 

which is the average percentage offset weighted by the amount of new floor area for each 

building type in a state. Figure 7-11 shows the weighted average offset for each state, 

with twelve of nineteen states realizing a negative offset. 

Figure 7-11 Weighted Average Offset by State 

Figure 7-12 shows the savings in energy costs per unit of savings in energy use ($/MWh) 

based on the price differential between electricity and natural gas ($/kWh) and the 

weighted average offset (%) for each state. States with a greater energy price differential 

combined with a greater weighted average offset realize the greatest energy cost savings 

per unit of energy use savings. 
82

Figure 7-12 Average State Energy Cost Savings per Unit of Energy Use Savings by 

Weighted Average Offset and Energy Price Differential 

7.3.1.4 Carbon Emissions Savings per Unit of Energy Use Savings 

In general, the states that realize the greatest reductions in energy use also realize the 

greatest reductions in energy-related carbon emissions. However, reductions in energy 

costs are also impacted by the per unit energy costs of electricity and natural gas and the 

fuel mix of the reductions in energy use in a state. Table E-5 shows the weighted average 

fraction of electricity consumption offset by a change in natural gas consumption, the 

average CO2 emissions rates for electricity and natural gas, and the reduction in cradle-tograve energy-related carbon emissions per unit of reduction in energy use for the nineteen

states in this study. States with the highest emissions rates for electricity generation tend 

to realize the greatest reductions in carbon emissions per unit of reduction in energy use. 

Relative to electricity emissions rates, natural gas has minimal impact on the relative 

reduction because natural gas emissions rates are constant across states and are 

significantly lower per unit of energy for all nineteen states. 

The correlation between a state’s average electricity emissions rate and the savings in 

energy-related emissions per unit of energy reduced is shown in Figure 7-13. States in the 

central U.S. and West Virginia have the highest average electricity emissions rates and 

tend to realize the greatest savings in carbon emissions per unit of savings in energy use. 

Meanwhile, states with the lowest average electricity emissions rates (e.g., Nevada) 

realize the smallest carbon emissions savings per unit of energy use savings. 

0.02

0.04

0.06

0.08

0.10

0.12

0.14

-60.0% -40.0% -20.0% 0.0% 20.0% 40.0% 60.0% 80.0%

Energy Price Differential ($/KWh)

Weighted Average Offset (%)

Energy Cost Savings ($/MWh)
83

Figure 7-13 Energy-related Carbon Emissions Savings per Unit of Energy Use 

Savings and Average Electricity Emissions Rate by State 

The electricity emissions rate does not explain all the variation across states in 

energy-related carbon emissions savings per unit of energy use savings because there are 

two sources of carbon emission savings: the carbon emissions savings from total energy 

use reduction, and the carbon emissions savings from the shifting of fuel consumption 

from the more carbon intensive electricity to less carbon intensive natural gas. The 

carbon emissions savings increase as the emissions rate differential increases because the 

carbon emissions savings for each unit of electricity “offset” by a unit of natural gas is 

greater. The greater the fraction of electricity consumption reductions offset by increases 

in natural gas consumption, the greater the carbon emissions savings per unit of energy 

use savings. 

Figure 7-14 shows the savings in carbon emissions per unit of savings in energy use 

(tCO2e/GWh) based on the emissions rate differential between electricity and natural gas 

(tCO2e/GWh) and the weighted average offset (%) for each state. States with a greater 

carbon emissions rate differential combined with a greater weighted average offset 

realize the greatest carbon emissions savings per unit of energy use savings. 
84

Figure 7-14 Average State Carbon Emissions Savings per Unit of Energy Use by 

Weighted Average Offset and Energy Emissions Rate Differential 

7.3.2 Regional and National Level Changes 

Table 7-11 shows the reduction in energy use per unit of newly constructed floor area 

from adopting the ASHRAE 90.1-2007 design by Census region. The only state in the 

Northeast Census Region (Maine) realizes the greatest reduction while states in the West 

Census Region realize the smallest reduction in energy use per unit of floor area. The 

nationwide weighted average reduction in energy use per unit of floor area is 

152 kWh/m2(14 kWh/ft2). The variation across Census regions is a result of a number of 

factors, including a location’s energy code and climate zone.

Table 7-11 Energy Use Reduction per Unit of Floor Area for Adoption of the 

ASHRAE 90.1-2007 Design by Census Region, 10-Year 

State Average Annual 

New Floor Area

1000 m2(1000 ft2)

Energy Use 

(GWh) kWh/m2

kWh/ft2

Northeast 497 (5349) 106 212 20

Midwest 6296 (67 767) 1140 181 17

South 12 750 (137 243) 1968 154 14

West 12 622 (135 861) 1668 132 12

Total 32 165 (346 220) 4881 152 14

Table 7-12 shows each Census Region’s natural gas rate, electricity rate, weighted 

average fraction of the reduction in electricity consumption offset by the change in 

natural gas consumption, and average reduction in energy costs from adopting the 

ASHRAE 90.1-2007 design. The Northeast Census Region has the highest average 

300

350

400

450

500

550

600

650

700

750

800

-60.0% -40.0% -20.0% 0.0% 20.0% 40.0% 60.0% 80.0%

Emissions Rate Differential 

(tCO2e/GWh)

Weighted Average Offset (%)

Carbon Emissions Savings (tCO2e/GWh)
85

electricity rate, and realizes the greatest reductions in energy costs per unit of reduction in 

energy use. Meanwhile, the Midwest Census Region has the smallest average electricity 

rate, and realizes the smallest reductions in energy costs per unit of reduction in energy 

use. 

Table 7-12 Energy Cost Reduction per kWh of Energy Use Reduction for Adoption 

of the ASHRAE 90.1-2007 Design by Census Region, 10-Year 

State Offset*

(%)

Electricity

Rate*

($/kWh)

Natural Gas

Rate*

($/kWh)

Energy Cost

Reduction

($/kWh)

Northeast -15 0.13 0.04 0.09

South -69 0.09 0.04 0.07

West -66 0.09 0.03 0.07

Midwest -1123 0.07 0.03 0.06

Total -276 0.09 0.03 0.06

*Weighted by energy use savings for a state

Table 7-13 shows each Census Region’s natural gas emissions rate, electricity emissions 

rate, weighted average fraction of the reduction in electricity consumption offset by the 

change in natural gas consumption, and average reduction in carbon emissions from 

adopting the ASHRAE 90.1-2007 design. The only state in the Northeast Census Region 

(Maine) has the lowest average electricity emissions rate, and realizes the smallest 

reductions in carbon emissions per unit of reduction in energy use. Even though the 

South Census Region does not have the largest average electricity emissions rate, it 

realizes the greatest reductions in carbon emissions per unit of reduction in energy use. 

This is because it has a greater (smaller negative) offset than the Midwest Census Region, 

leading to the South realizing greater carbon emissions savings per unit of energy use 

savings. 

Table 7-13 Carbon Reduction per GWh of Energy Use Reduction for Adoption of 

the ASHRAE 90.1-2007 Design by Census Region, 10-Year 

State Offset*

(%)

CO2e

Emissions Rate 

for Electricity*

(t/GWh)

CO2e

Emissions Rate 

for Natural Gas

(t/GWh)

CO2e

Reduction

(t/GWh)

South -69 825 241 867

Midwest -1123 950 241 761

West -66 838 241 710

Northeast -15 599 241 557

Total -276 854 241 774

*Weighted by energy use savings for a state
86

Table 7-14 shows the average life-cycle cost reduction per unit of new floor area by 

Census Region. The combination of greater energy use savings per unit of floor area and 

higher electricity rates tends to lead to greater life-cycle cost savings from adopting the 

ASHRAE 90.1-2007 design. The Census regions with the lowest electricity rate 

(Midwest) and the smallest energy use savings per unit of floor area (South) realize the 

lowest and 2nd-lowest life-cycle cost savings per unit of floor area, respectively. The 

West Census Region realizes greater life-cycle cost savings per unit of floor area than the 

Northeast Census Region, which may be driven by a number of factors, including 

baseline energy codes and local construction costs across the two regions. 

Table 7-14 Life-Cycle Cost Reductions per Unit of New Floor Area for Adoption of 

the ASHRAE 90.1-2007 Design by Census Region, 10-Year 

State

Energy Use 

Savings

(kWh/m2)

Electricity

Rate*

($/kWh)

LCC 

Savings 

($million)

LCC 

Savings 

($/m2)

LCC 

Savings 

($/ft2)

West 132 0.09 94.9 7.52 0.70

Northeast 212 0.13 3.3 6.64 0.62

South 154 0.09 67.4 5.29 0.49

Midwest 181 0.07 7.7 1.22 0.11

Total 156 0.09 173.3 5.39 0.50
87

8 Incremental Impacts from Adopting More Stringent Standard 

Editions 

This chapter estimates the incremental changes for a state adopting a more recent edition 

of ASHRAE 90.1 or the LEC design. Section 8.1 will consider incremental impacts on 

energy use at the state level. Section 8.2 will consider the incremental impacts on lifecycle costs at the state level. The analysis focuses on the nineteen states that have not yet 

adopted ASHRAE 90.1-2007.

8.1 Energy Use Savings 

In order to determine the incremental impacts of the adoption of more recent standard 

editions (a.k.a. impact from adopting the next edition), it is necessary to compare the total 

savings from adopting each design alternative for the 19 states analyzed in Chapter 7. 

Table 8-1 shows the incremental change in total energy use (GWh) by state from 

adopting the next edition of ASHRAE 90.1. The incremental impact from adopting 

ASHRAE 90.1-2001 is marginal relative to the more recent editions of ASHRAE 90.1 or 

the LEC design. The adoption of ASHRAE 90.1-2007 tends to realize a smaller increment 

in savings than adoption of the ASHRAE 90.1-2004 or LEC designs. 

Table 8-1 Incremental Change in Energy Use by State and Building Design, 10-

Year 

State Code

Incremental Change in Energy Use (GWh)

ASHRAE 

90.1-2001

ASHRAE

90.1-2004

ASHRAE 

90.1-2007

Low Energy 

Case

AK None 1.1 -3.0 15.8 85.4

ND None 3.2 9.7 32.7 58.9

WY None 2.7 19.4 12.9 41.7

SD None 3.4 25.6 28.5 64.8

ME None 5.6 41.3 58.5 111.2

OK None 38.1 220.6 41.7 297.6

KS None 23.4 122.2 83.8 209.1

MO None 35.3 309.8 178.9 460.6

AL None 48.9 469.5 113.2 419.0

MS None 34.3 302.5 133.8 218.9

AZ* None 449.2 497.1 911.2

AR 2001 173.6 30.7 221.8

CO 2001 308.8 234.1 570.0

WV 2001 58.7 37.7 80.7

HI 2004 12.1 126.3

SC 2004 92.2 502.3

NV 2004 117.3 591.7

TN 2004 172.6 635.2

MN 2004 282.7 534.0

Total 196.0 2507.9 2176.3 6140.4

*Excludes incremental changes from adopting ASHRAE 90.1-2001 because 

three cities in Arizona have adopted ASHRAE 90.1-2004.
88

Incremental change comparisons across states are not possible because the amount of 

new floor area varies across states. To control for this, Table 8-2 shows the reduction in 

energy use per unit of new floor area for each building design. On average, going beyond 

ASHRAE 90.1-2007 and adopting the LEC design leads to the greatest reductions 

(202 kWh/m2(19 kWh/ft2)) followed by the incremental reductions from adopting 

ASHRAE 90.1-2004 (112 kWh/m2(11 kWh/ft2)), ASHRAE 90.1-2007 (71 kWh/m2

(7 kWh/ft2)), and ASHRAE 90.1-2001 (16 kWh/m2

(1 kWh/ft2)).

Table 8-2 Change in Energy Use per Unit of Floor Area by State and Building 

Design, 10-Year 

State Code

Energy Use Savings per Unit of Floor Area

ASHRAE

90.1-2001

ASHRAE

90.1-2004

ASHRAE

90.1-2007

Low Energy

Case

kWh/m2kWh/ft2kWh/m2kWh/ft2kWh/ft2kWh/ft2kWh/m2kWh/ft2

AK None 4 0 -10 -1 54 5 294 27

AL None 22 2 208 19 50 5 186 17

KS None 22 2 113 11 78 7 194 18

ME None 11 1 83 8 118 11 224 21

MO None 15 1 131 12 76 7 195 18

MS None 27 3 242 22 107 10 175 16

ND None 14 1 42 4 143 13 257 24

OK None 24 2 139 13 26 2 187 17

SD None 11 1 84 8 94 9 214 20

WY None 12 1 84 8 56 5 181 17

AZ* None 94 9 104 10 192 18

AR 2001 146 14 26 2 187 17

CO 2001 94 9 71 7 173 16

WV 2001 123 11 79 7 168 16

HI 2004 23 2 236 22

MN 2004 121 11 229 21

NV 2004 33 3 168 16

SC 2004 34 3 185 17

TN 2004 53 5 194 18

Average 16 1 112 11 71 7 202 19

*Excludes incremental changes from adopting ASHRAE 90.1-2001 because three cities in Arizona have adopted 

ASHRAE 90.1-2004.

Figure 8-1 shows the incremental energy use savings for each energy standard edition as 

a fraction of the sum of the positive incremental savings in energy use. For a standard 

edition that increases energy use (e.g., ASHRAE 90.1-2004 for Alaska), the impact is 

estimated as a negative fraction of the total savings from the editions that increase energy 

use savings (e.g., the ASHRAE 90.1-2001, ASHRAE 90.1-2007, and LEC designs for 

Alaska). 

The states that have already adopted ASHRAE 90.1-2004 realize a greater share of their 

savings from the LEC design (65.4 % to 91.3 %) because the difference between 

ASHRAE 90.1-2004 and ASHRAE 90.1-2007 design requirements are minimal relative to 
89

the additional energy efficiency requirements for the LEC design. For states that have no 

state energy code or have adopted ASHRAE 90.1-2001, the LEC design accounts for 

31.8 % to 56.3 % while the ASHRAE 90.1-2004 design accounts for -2.9 % to 44.7 % of 

the energy use savings. The ASHRAE 90.1-2004 design accounts for a greater percentage 

of energy use savings than the ASHRAE 90.1-2007 design for 9 of 14 states. There are 

minimal impacts from adopting ASHRAE 90.1-2001 because there are few differences in 

energy efficiency requirements relative to ASHRAE 90.1-1999.

Figure 8-1 Incremental Energy Use Savings by State and Standard Edition 

Since energy costs and energy-related carbon emissions are highly correlated with energy 

use, the same trends and interpretations hold for the incremental changes in energy costs 

and carbon emissions. Variation from energy use is due to a state’s energy prices, energy 

emissions rates, and the relative changes in energy use for electricity and natural gas 

consumption discussed in Section 6.2 and Section 7.2.

8.2 Life-Cycle Cost Savings 

In order to determine the incremental life-cycle cost impacts of the adoption of more 

recent standard editions, it is necessary to compare the total life-cycle costs from 

adopting each design alternative for the 19 states analyzed in Chapter 7. 

Table 8-3 shows the incremental change in life-cycle cost savings ($ million) by state and 

building design. Adopting ASHRAE 90.1-2001 can lead to significant increases in 

life-cycle costs ($2.9 million to $37.3 million) for all states, which is a result of the 

-10%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

AK AL KS ME MO MS ND OK SD WY AZ* AR CO WV HI MN NV SC TN

None None None None None None None None None None None 2001 2001 2001 2004 2004 2004 2004 2004

Low Energy Case ASHRAE 90.1-2007 ASHRAE 90.1-2004 ASHRAE 90.1-2001
90

high-cost HVAC efficiency requirement increases relative to ASHRAE 90.1-1999.

Adopting ASHRAE 90.1-2004 can lead to significant decreases in life-cycle costs relative 

to ASHRAE 90.1-2001 ($3.6 million to $91.1 million) for all nine states and offsets most, 

if not all of the additional life-cycle costs from adopting ASHRAE 90.1-1999. Five of the 

nine states with no state energy code realize a net decrease in life-cycle costs from 

adopting ASHRAE 90.1-2004.

26 The adoption of the ASHRAE 90.1-2007 design realize 

much smaller savings relative to ASHRAE 90.1-2004 (-$0.2 million to $46.6 million).

The adoption of the LEC design realizes similar incremental savings relative to ASHRAE 

90.1-2007 (-$0.2 million to $48.3 million). At the margin, adopting the ASHRAE 

90.1-2007 and LEC designs increase life-cycle costs for two states (Oklahoma and 

Arkansas) and one state (West Virginia), respectively. 

Table 8-3 Incremental Change in Life-Cycle Cost Reductions by State and Building 

Design, 10-Year 

State Code

Incremental Change in Life-Cycle Cost Savings

($ million)

ASHRAE 

90.1-2001

ASHRAE

90.1-2004

ASHRAE 

90.1-2007

Low Energy 

Case

AK None -3.8 4.6 0.6 0.9

AL None -30.1 48.7 7.2 11.3

KS None -22.3 15.4 3.9 5.2

ME None -7.9 9.2 1.9 3.1

MO None -37.3 32.2 7.0 0.8

MS None -21.4 26.7 7.0 2.5

ND None -3.4 2.6 0.8 0.0

OK None -26.2 20.6 -0.2 6.4

SD None -2.9 3.6 0.7 0.9

WY None -3.9 3.7 0.7 0.2

AZ* None 91.1 46.6 48.3

AR 2001 17.7 -0.1 2.8

CO 2001 46.1 7.8 5.8

WV 2001 5.6 1.8 -0.2

HI 2004 2.0 11.9

MN 2004 7.3 5.1

NV 2004 6.3 11.6

SC 2004 2.9 9.3

TN 2004 7.5 20.6

Total -159.2 327.8 111.7 146.5

*Excludes incremental changes from adopting ASHRAE 90.1-2001 because 

three cities in Arizona have adopted ASHRAE 90.1-2004.

Incremental change comparisons across states are not possible because the amount of 

new floor area varies across states. Table 8-4 shows the reduction in life-cycle costs per 

unit of new floor area for each building design. On average, adopting the ASHRAE 90.1-

 

26 Excluding Arizona. 
91

2004 design leads to the greatest marginal reductions ($15.52/m2

($1.44/ft2)) followed by 

the LEC design ($4.24/m2($0.39/ft2)), ASHRAE 90.1-2007 ($3.04/m2($0.28/ft2)), and 

ASHRAE 90.1-2001 (-$15.39/m2(-$1.43/ft2)). There is significant variation in 

incremental life-cycle cost savings per unit of floor area within each building design. 

Table 8-4 Incremental Change in Life-Cycle Cost Reductions per Unit of New Floor 

Area by State and Building Design, 10-Year 

State Code

Incremental Change in Life-cycle Cost Savings

per Unit of Floor Area

ASHRAE 

90.1-2001

ASHRAE 

90.1-2004

ASHRAE 

90.1-2007

Low Energy 

Case

$/m2 $/ft2 $/m2 $/ft2 $/m2 $/ft2 $/m2 $/ft2

AK None -13.10 -1.22 15.86 1.48 2.07 0.19 3.10 0.29

--AL None -13.35 -1.24 21.61 2.01 3.19 0.30 5.01 0.47

KS None -20.71 -1.92 14.30 1.33 3.62 0.34 4.83 0.45

ME None -15.90 -1.48 18.51 1.72 3.82 0.36 6.24 0.58

MO None -15.82 -1.47 13.66 1.27 2.97 0.28 0.34 0.03

MS None -17.11 -1.59 21.34 1.98 5.60 0.52 2.00 0.19

ND None -14.85 -1.38 11.35 1.06 3.49 0.32 0.00 0.00

OK None -16.48 -1.53 12.96 1.20 -0.13 -0.01 4.03 0.37

SD None -9.57 -0.89 11.88 1.10 2.31 0.21 2.97 0.28

WY None -16.96 -1.57 16.09 1.49 3.04 0.28 0.87 0.08

AZ* None 19.15 1.78 9.79 0.91 10.15 0.94

AR 2001 14.92 1.39 -0.08 -0.01 2.36 0.22

CO 2001 14.00 1.30 2.37 0.22 1.76 0.16

WV 2001 11.69 1.09 3.76 0.35 -0.42 -0.04

HI 2004 3.73 0.35 22.20 2.06

MN 2004 3.13 0.29 2.19 0.20

NV 2004 1.79 0.17 3.30 0.31

SC 2004 1.07 0.10 3.42 0.32

TN 2004 2.29 0.21 6.30 0.58

Average -15.39 -1.43 15.52 1.44 3.04 0.28 4.24 0.39

*Excludes incremental changes from adopting ASHRAE 90.1-2001 because three cities 

in Arizona have adopted ASHRAE 90.1-2004.

Figure 8-2 shows the incremental life-cycle cost savings for each energy standard edition 

as a fraction of the sum of the positive incremental savings in life-cycle costs. For a 

standard edition that increases life-cycle costs (e.g., ASHRAE 90.1-2001), the impact is 

estimated as a negative fraction of the total savings from the editions that increase 

life-cycle cost savings (e.g., the ASHRAE 90.1-2004, ASHRAE 90.1-2007, and LEC 

designs).

The fraction of the life-cycle cost savings resulting from adopting the LEC design varies 

across states that have already adopted ASHRAE 90.1-2004 (41.1 % to 85.6 %). For states 

that have no state energy code or have adopted ASHRAE 90.1-2001, the ASHRAE 

90.1-2004 design accounts for 49.0 % to 86.3 % while the ASHRAE 90.1-2007 design 

accounts for -0.7 % to 58.9 % of the life-cycle cost savings. The ASHRAE 90.1-2004
92

design accounts for the greatest percentage of life-cycle cost savings (49.0 % to 86.3 %). 

There are significant negative impacts from adopting ASHRAE 90.1-2001, which offset 

44.8 % to 100.0 % of life-cycle cost savings from adopting the ASHRAE 90.1-2004, 

ASHRAE 90.1-2007, and LEC designs. 

Figure 8-2 Incremental Life-cycle Cost Savings by State and Building Design 

-100%

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

AK AL KS ME MO MS ND OK SD WY AZ* AR CO WV HI MN NV SC TN

None None None None None None None None None None None 2001 2001 2001 2004 2004 2004 2004 2004

Low Energy Case ASHRAE 90.1-2007 ASHRAE 90.1-2004 ASHRAE 90.1-2001
93

9 Discussion 

This study analyzes the impacts of adopting new, more stringent state energy codes based 

on the BIRDS database for 11 prototypical building types in 228 U.S. locations. Results 

are summarized at the state, regional, and national levels. This section will discuss key 

findings, limitations of the research, and recommended directions for future research. 

9.1 Key Findings 

The key findings from this study are described for each metric used for the analysis: 

percentage change, total change, and change per unit of floor area. Additionally, 

incremental changes, both in aggregate and per unit of floor area, will be discussed.

9.1.1 Percentage Changes 

Overall, adoption of ASHRAE 90.1-2007 for the 19 states that have not yet adopted it as 

their state energy code leads to percentage reductions in energy use, energy costs, and 

energy-related carbon emissions. The average percentage reduction in energy use for new 

commercial buildings is 9.6 % while energy costs and carbon emissions realize average 

reductions of 12.2 % and 12.4 %, respectively. The reductions in energy use and carbon 

emissions are cost-effective, with average life-cycle costs decreasing by 0.7 % over a 10-

year study period. 

However, ASHRAE 90.1-2007 does not lead to energy efficiency improvements over 

older editions of ASHRAE 90.1 for all locations in the U.S. for two reasons. First, the 

simplification of the ASHRAE climate zones from 26 zones in ASHRAE 90.1-2001 to 

eight zones in ASHRAE 90.1-2004 resulted in the relaxation of some building envelope 

requirements for some locations. Second, ASHRAE 90.1-2007 has less stringent solar heat 

gain coefficient (SHGC) requirements relative to ASHRAE 90.1-2004 for some climate 

zones. As a result, high-rise, 100 % glazed buildings realize smaller reductions, and 

occasionally increases, in energy use because the less stringent window requirements 

overwhelm the stricter requirements for other energy efficiency measures analyzed in this 

study. 

Overall, adoption of the LEC design in all 50 states leads to average nationwide 

percentage reductions in energy use, energy costs, and carbon emissions greater than 

those realized by ASHRAE 90.1-2007. The average reduction in energy use is 17.8 % 

over current state energy codes while energy costs and carbon emissions realize average 

reductions of 22.6 % and 20.4 %, respectively. The reductions in energy use and carbon 

emissions are cost-effective, with life-cycle costs decreasing by 1.1 % on average for a 

10-year study period. 
94

States with current energy codes based on older editions of ASHRAE 90.1 realize greater 

percentage reductions in energy use, energy costs, and carbon emissions for the ASHRAE 

90.1-2007 design. For a small office building, the 13 states with reductions in energy use 

of at least 10 % have no state energy code or have adopted ASHRAE 90.1-2001. For the 

LEC design, 14 of the 18 states that realize reductions in energy use greater than 25 % 

have no state energy code or have adopted ASHRAE 90.1-1999/2001, including all 13 

states with reductions greater than 30 %. Similar trends hold for energy costs and 

energy-related carbon emissions. 

Over all building types, states located in the warmest climates realize the greatest 

reductions in energy use from adopting the “Low Energy Case” (LEC) design because 

several of the energy efficiency improvements (e.g., overhangs and daylighting controls) 

are more beneficial for warmer climates. However, states in colder climates see greater 

percentage reductions in energy costs and carbon emissions per percentage reduction in 

energy use because the energy efficiency measures tend to shift some energy use from 

electricity to natural gas consumption. Electricity is more expensive per unit of energy 

and typically has greater CO2e emissions per unit of energy relative to natural gas. 

Therefore the shift of energy consumption from electricity to natural gas can lead to 

greater reductions in energy costs and energy-related carbon emissions than reductions in 

total energy use. In an extreme case, cities located in Zone 8 realize a reduction in energy 

costs and carbon emissions while realizing an increase in total energy use. 

The results for the ASHRAE 90.1-2007 design have some similarities and some 

differences relative to the results for the LEC design. Similar to the LEC design, the 

current state energy codes are a key driver of variation in the results. The variation across 

climate zones diverges depending on the state energy code. For locations in states that 

have not adopted any state energy code or have adopted older editions of ASHRAE 90.1

(-2001), warmer climate zones realize greater percentage reductions in energy use. For 

cities located in states that have adopted ASHRAE 90.1-2004, the percentage reductions 

in energy use do not follow the same trend. Instead the percentage changes are the 

greatest for cities in Zone 2 followed by Zone 7 and smallest for cities in Zone 1 and 

Zone 3. 

Similar to the LEC design results, some cities realize a shift in energy use from electricity 

to natural gas, which decreases energy costs and carbon emissions by a greater 

percentage than the percentage decrease in energy consumption. However, when 

averaged across all cities in a climate zone, nearly all zones realize smaller percentage 

reductions in carbon emissions than the percentage reductions in energy use because 

adopting ASHRAE 90.1-2007 decreases consumption of natural gas by a greater 

percentage than electricity for most cities.
95

The length of the study period impacts life-cycle cost-effectiveness to some degree. 

Assuming nationwide adoption of the LEC design, average life-cycle costs decrease by 

1.1 %, on average, for all building types and locations over a 10-year study period. The 

percentage decrease in life-cycle costs is 1.4 % for a 20-year, 1.8 % for a 30-year, and 

1.9 % for a 40-year study period. As the study period length increases from 5 years to 40 

years, life-cycle cost-effectiveness tends to increase for more energy efficient commercial 

building designs. 

9.1.2 Total Changes 

By combining the amount of new floor area in a state with its average impacts in a state 

for each building type, it is possible to estimate the magnitude of the impacts that 

nationwide adoption of a given building design would have at the state and national 

levels. States with the most newly constructed commercial building floor area tend to 

realize the greatest total energy use, energy cost, energy-related carbon emissions, and 

life-cycle cost reductions from adopting the ASHRAE 90.1-2007 and LEC designs even if 

those states do not realize the greatest percentage reductions. California, Florida, and 

Texas realize the greatest reductions in energy use (>1900 GWh) from adopting the LEC 

design. In comparison, states with the smallest amount of new floor area (Alaska, 

Delaware, Montana, Rhode Island, Vermont, and Wyoming) realize savings of less than 

100 GWh from adopting the LEC design. For the nineteen states that have not yet 

adopted the ASHRAE 90.1-2007 design, Arizona realizes the greatest reductions in 

energy use (946 GWh) from doing so, while states with the smallest amount of new floor 

area (Alaska, Wyoming, Hawaii, Maine, North Dakota, South Dakota, and Wyoming) 

realize savings of less than 106 GWh. Similar trends occur for total energy cost 

reductions and energy-related carbon emissions savings. 

The nationwide adoption of more efficient energy codes decreases total life-cycle costs. 

Adopting the LEC design decreases total life-cycle costs for 48 of 50 states for a 10-year 

study period, with Florida ($151.3 million), California ($124.9 million), and Texas 

($106.8 million) realizing the greatest life-cycle cost savings. The two states that realize 

an increase in life-cycle costs are Oregon ($0.4 million) and Washington ($11.5 million). 

For a 10-year study period, adopting the ASHRAE 90.1-2007 design reduces total 

life-cycle costs for 17 of 19 states, including 8 of 10 that have adopted an older edition of 

ASHRAE 90.1 or have not yet adopted a state energy code for commercial buildings. The 

greatest life-cycle cost savings are realized by Colorado ($53.9 million), Arizona 

($30.8 million), and Alabama ($25.7 million). The two states that realize an increase in 

total life-cycle costs are Kansas ($2.9 million) and Oklahoma ($5.7 million). 

The state-level impacts are aggregated to determine the total impact of nationwide 

adoption of both the ASHRAE 90.1-2007 and LEC designs. Nationwide adoption of the 

LEC design leads to reductions totaling 34.4 TWh in energy consumption, $2.8 billion in 
96

energy costs, 26.3 million metric tons in energy-related carbon emissions, and 

$1.0 billion in life-cycle costs for a 10-year study period. Nationwide adoption of the 

ASHRAE 90.1-2007 design leads to reductions totaling 4.9 TWh in energy consumption, 

$312 million in energy costs, 3.8 million metric tons in energy-related carbon emissions, 

and $173 million in life-cycle costs for a 10-year study period. An increase in the study 

period length increases the total savings for all four impacts because as the length of the 

study period increases, energy cost savings become a greater fraction of total life-cycle 

cost savings.

9.1.3 Change per Unit of Floor Area 

The total savings estimates are driven primarily by the average annual amount of new 

floor area in a state. After controlling for the amount of new floor area, the relative 

savings in energy use, energy costs, carbon emissions, and life-cycle costs per unit of 

floor area across states is similar to the average percentage changes in each impact. States 

that have adopted older editions of ASHRAE 90.1 or have no energy code realize greater 

per unit savings in energy use, energy costs, and carbon emissions from adopting the 

LEC design. However, since these per unit changes account for the amount of new floor 

area for each building type, the results more precisely estimate the impacts. States that 

have adopted the ASHRAE 90.1-2001 design realize the greatest life-cycle cost savings 

per unit of floor area from adopting both the ASHRAE 90.1-2007 and LEC designs. On 

the other hand, states that have no state energy code realize varying levels of savings 

from adopting both the ASHRAE 90.1-2007 and LEC designs.

In general, the states that realize the greatest reductions in energy use per unit of floor 

area also realize the greatest reductions in energy costs and energy-related carbon 

emissions per unit of floor area. However, states with higher average electricity prices 

and electricity emissions rates, and states that realize a greater shift of fuel consumption 

from electricity to natural gas, realize greater reductions in energy costs and carbon 

emissions holding energy use savings constant. 

The changes per unit of floor area vary across Census regions, with the same trends 

holding for adoption of the ASHRAE 90.1-2007 and LEC designs. The South realizes the 

greatest energy use savings per unit of floor area because all states in the region are 

located in warmer climate zones. The West realizes the greatest life-cycle cost savings 

per unit of floor area, which is a result of a number of factors, including the baseline 

energy codes for the cities located in the Census region, the regional average electricity 

price, average energy use savings, and local construction costs. Similar to state-level 

results, energy costs and carbon emissions savings vary from energy use savings per unit 

of floor area. The Northeast realizes the greatest energy cost savings per unit energy use 

savings due to its higher average electricity price. The Midwest realizes the greatest 
97

carbon emissions savings per unit of energy use savings because its average electricity 

emissions rate is much higher than in the other Census regions. 

9.1.4 Incremental Changes from Adopting More Stringent Standard 

Editions 

The incremental impacts in a state from adopting each newer edition of ASHRAE 90.1

lead to some interesting conclusions. For the nine states that have no state energy code, 

adoption of ASHRAE 90.1-2001 would lead to minimal energy use reductions 

(16 kWh/m2) while significantly increasing total life-cycle costs ($15.39/m2).27 The 

reason for this result is that the primary changes in the standard from ASHRAE 90.1-1999

to ASHRAE 90.1-2001 target the required efficiencies of HVAC equipment. The 

additional first costs of increasing the efficiency of HVAC equipment appear to be 

greater than the energy cost savings realized over the 10-year study period. 

The adoption of ASHRAE 90.1-2004 leads to significant average reductions in energy use 

(112 kWh/m2) while significantly decreasing total life-cycle costs ($15.52/m2), and 

entirely offsets the increase in life-cycle costs for five of the nine states with no state 

code. One state, Alaska, realizes an increase in energy use relative to ASHRAE 

90.1-2001, which is a result of building requirements being relaxed for some cities due to 

the climate zone consolidation from ASHRAE 90.1-2001 to ASHRAE 90.1-2004.

The adoption of ASHRAE 90.1-2007 leads to significantly smaller average incremental 

reductions in energy use (71 kWh/m2

) and life-cycle costs ($3.04/m2) relative to adopting 

ASHRAE 90.1-2004. Two of the nineteen states (Arkansas and Oklahoma) realize an 

increase in life-cycle costs relative to ASHRAE 90.1-2004. 

The adoption of the LEC design leads to the greatest incremental impacts on total energy 

use (202 kWh/m2), and similar incremental impacts on life-cycle costs ($4.24/m2) as 

ASHRAE 90.1-2007 for the nineteen states that have not yet adopted ASHRAE 90.1-2007. 

Only one of the nineteen states (West Virginia) realizes an increase in life-cycle costs 

relative to ASHRAE 90.1-2007.

9.2 Limitations and Future Research 

The analysis in this study is limited in scope and would be strengthened by including 

sensitivity analysis, expanding the BIRDS database and metrics, and enabling public 

access to all the results. 

Sensitivity analysis is needed for at least two assumptions in the analysis. First, consider 

the assumed discount rate. Although 3 % is a reasonable discount rate, in real terms, for 

 

27 Excludes Arizona because three of the six cities in the BIRDS database have adopted ASHRAE 

90.1-2004 as their local energy code. 
98

federal government investment decisions, it may be too low of a value for an expected 

real return on an alternative investment in the private sector. Sensitivity analysis on the 

assumed discount rate is needed to determine the robustness of the cost results. Second, 

the current analysis assumes that the cooling load is met by equipment running on 

electricity while heating loads are met with equipment running on natural gas, which is 

not the typical fuel mix for some areas of the nation. The database should be expanded to 

include alternative fuel source options, such as heating oil use in the New England area. 

Additional data are needed to refine and expand the BIRDS database. First, the study uses 

simple averages to summarize energy use, energy cost, life-cycle cost, and carbon 

emissions changes across all locations in a state. However, the amount of total floor area 

constructed will vary significantly from city to city. Future research could develop a 

weighted average of savings in a state based on the fraction of new construction by city. 

Second, the 11 prototypical buildings analyzed in this study are likely not representative 

of the entire building stock for each building type. For example, all high-rise buildings 

are not 100 % glazed. For this reason, the results should be considered as general 

magnitudes instead of hard numbers. Future research should include additional 

prototypes, such as the DOE Benchmark Buildings, in the database. Additionally, since 

existing buildings account for nearly the entire building stock, prototypes for energy 

retrofits to buildings should be incorporated into the BIRDS database as well. The state 

average energy cost rates and energy-related carbon emissions rates do not control for 

local variation in energy tariffs or electricity fuel mixes. By using utility-level energy cost 

and emissions rate data, the accuracy of the estimates in BIRDS could be improved. 

The analysis in this study ignores the impacts that plug and process loads have on the 

reductions in energy use. Buildings with greater plug and process loads will realize 

smaller percentage changes in energy use because the energy efficiency measures 

considered in this study focus on the building envelope and HVAC equipment, holding 

constant the energy use from other equipment used in the building. As building energy 

efficiency improves, the plug and process loads become a larger fraction of the overall 

energy load. Future research should consider the impact the assumed plug and process 

loads have on the overall energy savings realized by energy efficiency improvements to

buildings. 

This study only compares the current state energy code to newer, more stringent standard 

editions. The BIRDS database is much more expansive, allowing researchers to compare 

any of the editions of ASHRAE 90.1 with any other edition of ASHRAE 90.1 or the LEC 

design. The BIRDS database should be made available to the public through a simple-touse software tool that allows other researchers to use the database for their own research 

on building energy efficiency. 
99

Finally, a more comprehensive sustainability assessment of the benefits and costs of 

building energy efficiency would increase the impact of this work. This study applies 

environmental life cycle assessment methods to evaluate the global warming potentials 

attributable to building energy efficiency improvements. In a parallel effort, the BIRDS 

database is being expanded to include a full range of 11 life-cycle environmental impacts 

covering human health effects, ecological health effects, and resource depletion. The 

sustainability assessment is also being expanded beyond building energy efficiency to 

cover the materials used in construction, MRR, and waste management. The BIRDS 

software tool in development will provide the results of this more comprehensive 

sustainability assessment alongside the results summarized in this report.
100
101

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104
105

A Building Type, New Construction, and Emissions Rates 

Table A-1 CBECS Categories and Subcategories 

Category Subcategory Category Subcategory

Education elementary or middle school

high school

college or university

preschool or daycare

adult education

career or vocational training

religious education

Public 

Assembly

social or meeting 

recreation

entertainment or culture

library

funeral home

student activities center

armory

exhibition hall

broadcasting studio

transportation terminal

Food Sales grocery store or food market

gas station with a convenience 

store;

convenience store

Food Service fast food

restaurant or cafeteria

Public Order 

and Safety

police station

fire station

jail, reformatory, or penitentiary

courthouse or probation office

Health Care 

Inpatient

hospital

inpatient rehabilitation

Religious 

Worship

None

Health Care 

Outpatient

medical office (see previous 

column)

clinic or other outpatient health 

care

outpatient rehabilitation

veterinarian

Service vehicle service or vehicle repair shop

vehicle storage/ maintenance (car 

barn)

repair shop

dry cleaner or laundromat

post office or postal center

car wash

gas station

photo processing shop

beauty parlor or barber shop

tanning salon

copy center or printing shop

kennel

Lodging motel or inn

hotel

dormitory, fraternity, or sorority

retirement home

nursing home, assisted living, etc.

convent or monastery

shelter, orphanage, halfway house
106

Mercantile NonMallretail store

beer, wine, or liquor store

rental center

dealership or showroom for 

vehicles or boats

studio/gallery

Warehouse 

and Storage

refrigerated warehouse

non-refrigerated warehouse

distribution or shipping center

Other airplane hangar

crematorium

laboratory

telephone switching

agricultural with some retail space

manufacturing or industrial with 

some retail space

data center or server farm

Mercantile Malls enclosed mall

strip shopping center

Office administrative or professional 

office

government office

mixed-use office

bank or other financial institution

medical office (see previous 

column)

sales office

contractor's office 

non-profit or social services

research and development

city hall or city center

religious office

call center

Vacant None
107

Table A-2 New Commercial Building Construction Volume for 2003 through 2007 

by State and Building Type (S-I)

State Building Construction Volume (1,000 m2)

Apartment Healthcare Hotel Office Public Assembly Restaurant Retail School Warehouse No Prototype Total

AK 19 130 126 226 111 13 208 231 126 259 1448

AL 801 705 853 1504 639 169 2485 1534 842 1740 11 272

AR 118 465 483 647 335 77 1359 1295 335 815 5928

AZ 1043 1505 1047 4030 1180 271 4891 2294 3721 3808 23 790

CA 9761 3310 3129 9219 3092 534 10 623 7085 13 364 12 345 72 462

CO 2033 1387 997 2158 708 199 2896 1654 1541 2889 16 461

CT 611 403 489 618 510 65 1245 1194 817 1271 7223

DC 1174 71 111 1462 112 4 104 191 34 830 4092

DE 70 155 124 224 119 16 237 290 160 323 1719

FL 21 397 3399 2979 9031 3124 678 11 904 7760 9692 12 748 82 712

GA 3696 1551 1510 3630 1212 331 5893 5580 7449 5350 36 202

HI 1280 91 92 171 59 9 273 92 132 485 2682

IA 143 639 427 999 657 74 1350 1262 621 1062 7234

ID 233 372 221 716 230 46 699 636 360 496 4008

IL 7303 1765 1304 2930 1714 232 5660 3083 6473 4179 34 643

IN 360 1728 856 1746 1323 255 3302 2558 3771 2415 18 313

KS 98 533 353 877 295 97 1122 826 513 670 5384

KY 268 757 643 1167 760 138 1667 1270 2001 1106 9778

LA 169 650 807 1175 593 135 1736 842 1011 1379 8498

MA 2959 728 884 1103 632 121 1772 1356 854 2484 12895

MD 3341 813 826 2802 580 109 1549 1527 1989 3388 16 924

ME 64 209 166 224 134 34 566 313 281 494 2485

MI 446 1797 713 1696 1359 200 3245 2058 864 2442 14 820

MN 1437 1018 473 1633 527 102 2135 1175 803 2342 11 645

MO 875 940 881 1226 780 158 2513 1626 819 1972 11 791

MS 150 336 479 631 411 55 1166 743 1593 692 6255

MT 45 122 118 149 94 18 253 174 76 142 1190

NC 1607 1362 1178 3368 1119 230 4472 3418 1910 3520 22 185

ND 7 118 91 138 113 14 331 174 57 100 1145

NE 147 453 303 631 331 54 1149 514 340 676 4599

NH 141 227 226 276 154 51 648 411 191 438 2763

NJ 2807 796 943 1235 774 112 2494 2627 3008 2587 17 382

NM 89 247 418 617 350 62 765 752 292 491 4083

NV 2867 528 2963 1626 1195 157 2382 960 1669 3231 17 579

NY 11 622 1639 1959 3330 1075 210 3633 2247 1286 3354 30 354

OH 635 2452 925 2674 1266 372 5132 4452 3382 3243 24 533

OK 115 794 512 763 878 141 1364 1179 932 1271 7950

OR 1253 918 360 922 383 68 1382 651 1142 1648 8727

PA 1503 1908 1406 2424 1354 219 3762 3660 3512 3556 23 305

RI 238 60 192 251 81 26 278 197 114 236 1674

SC 1981 746 563 1539 539 168 2600 2222 1101 2132 13 590

SD 13 119 86 257 126 13 341 268 88 205 1515

TN 987 1036 683 2296 733 199 3581 1809 2698 2337 16 360

TX 5548 4508 3571 8328 3325 849 13 121 12 693 10 609 9676 72 230

UT 622 569 314 1365 475 76 1424 1269 1274 1201 8590

VA 3502 1011 1361 3693 1096 200 3014 2387 1826 4406 22 495

VT 161 99 96 113 71 6 63 136 88 165 998

WA 3397 1085 871 2435 833 107 2504 1841 1880 3598 18 551

WI 906 1519 583 1556 746 137 2489 1129 882 1981 11 928

WV 65 215 148 193 117 39 668 484 179 288 2397

WY 4 72 166 66 127 9 158 254 67 228 1151

Total 100 111 48 059 41 007 92 089 38 550 7661 128 609 94 383 98 773 118 693 767 935
108

Table A-3 New Commercial Building Construction Volume for 2003 through 2007 

by State and Building Type (I-P)

State Building Construction Volume (1,000 ft2

)

Apartment Healthcare Hotel Office Public Assembly Restaurant Retail School Warehouse No Prototype Total

AK 201 1401 1357 2428 1190 137 2240 2484 1356 2787 15 581

AL 8619 7587 9184 16 191 6876 1821 26 748 16 514 9060 18 729 121 329

AR 1272 5000 5198 6962 3611 829 14 624 13 936 3609 8768 63 810

AZ 11 223 16 195 11 272 43 383 12 701 2918 52 646 24 692 40 052 40 986 256 068

CA 105 071 35 633 33 678 99 228 33 281 5747 114 344 76 262 143 853 132 882 779 978

CO 21 885 14 926 10 735 23 225 7618 2142 31 177 17 804 16 582 31 094 177 186

CT 6582 4333 5261 6651 5485 698 13 403 12 856 8798 13 679 77 746

DC 12 636 769 1199 15 734 1202 38 1122 2051 363 8934 44 047

DE 755 1672 1330 2410 1282 173 2551 3126 1722 3480 18 501

FL 230 315 36 591 32 071 97 212 33 622 7299 128 133 83 524 104 327 137 213 890 306

GA 39 780 16 699 16 254 39 076 13 043 3563 63 430 60 062 80 180 57 586 389 672

HI 13 773 979 989 1838 630 95 2939 985 1417 5220 28 865

IA 1542 6875 4598 10 749 7069 796 14 534 13 586 6688 11 426 77 863

ID 2506 4001 2375 7703 2478 493 7526 6847 3876 5343 43 147

IL 78 609 18 998 14 037 31 542 18 451 2497 60 928 33 180 69 674 44 977 372 893

IN 3875 18 600 9210 18 791 14 242 2747 35 539 27 535 40 591 25 992 197 123

KS 1057 5734 3795 9442 3178 1039 12 076 8892 5521 7216 57 950

KY 2888 8150 6922 12 558 8185 1489 17 941 13 672 21 538 11 906 105 248

LA 1823 7001 8689 12 647 6386 1454 18 681 9061 10 886 14 841 91 469

MA 31 854 7832 9516 11 868 6808 1306 19 079 14 599 9197 26 742 138 802

MD 35 967 8750 8888 30 163 6242 1173 16 672 16 432 21 414 36 463 182 163

ME 687 2245 1791 2411 1441 368 6088 3374 3021 5320 26 745

MI 4800 19 346 7671 18 251 14 629 2153 34 934 22 151 9305 26 283 159 523

MN 15 465 10 954 5093 17 575 5673 1098 22 985 12 643 8643 25 212 125 342

MO 9420 10 121 9483 13 197 8395 1705 27 054 17 497 8818 21 226 126 915

MS 1613 3618 5153 6789 4423 587 12 551 7999 17 146 7447 67 326

MT 481 1313 1265 1602 1007 195 2723 1871 821 1533 12 810

NC 17 294 14 663 12 678 36 249 12 044 2481 48 139 36 794 20 559 37 891 238 792

ND 76 1265 982 1490 1221 155 3567 1871 617 1077 12 320

NE 1586 4880 3263 6790 3562 577 12 369 5533 3660 7279 49 498

NH 1523 2440 2437 2974 1653 548 6970 4421 2059 4717 29 741

NJ 30 209 8563 10 145 13 295 8335 1210 26 842 28 280 32 383 27 841 187 103

NM 957 2655 4499 6636 3770 670 8235 8097 3142 5290 43 950

NV 30 856 5684 31 894 17 504 12 863 1691 25 644 10 337 17 969 34 776 189 218

NY 125 095 17 639 21 083 35 842 11 572 2259 39 107 24 186 13 845 36 104 326 732

OH 6832 26 393 9959 28 780 13 630 4004 55 245 47 919 36 400 34 909 264 071

OK 1242 8547 5511 8216 9450 1523 14 686 12 691 10 032 13 680 85 577

OR 13 492 9885 3878 9927 4118 728 14 881 7004 12 291 17 738 93 941

PA 16 177 20 535 15 135 26 096 14 577 2361 40 489 39 397 37 805 38 280 250 852

RI 2559 649 2069 2707 877 278 2990 2125 1228 2540 18 021

SC 21 321 8033 6056 16 562 5801 1810 27 984 23 920 11 848 22 949 146 284

SD 142 1285 922 2767 1354 138 3668 2884 950 2202 16 312

TN 10 621 11 152 7347 24 718 7891 2145 38 548 19 476 29 045 25 152 176 095

TX 59 723 48 519 38 437 89 641 35 794 9142 141 238 136 629 114 193 104 156 777 473

UT 6695 6123 3384 14 698 5110 822 15 331 13 657 13 716 12 926 92 462

VA 37 694 10 887 14 646 39 749 11 794 2149 32 438 25 691 19 659 47 422 242 129

VT 1736 1063 1030 1214 765 68 674 1463 946 1777 10 737

WA 36 566 11 683 9378 26 209 8964 1147 26 954 19 817 20 236 38 731 199 685

WI 9754 16 350 6273 16 751 8030 1474 26 793 12 148 9497 21 325 128 395

WV 697 2314 1592 2081 1259 421 7191 5215 1930 3098 25 797

WY 42 774 1787 713 1370 97 1696 2737 718 2453 12 387

Total 1 077 585 517 302 441 399 991 233 414 953 82 459 1 384 339 1 015 925 1 063 186 1 277 597 8 265 977
109

Table A-4 New Commercial Building Construction Share by State and Building 

Type 

State

Percentage of Building Construction Volume

Apartment Healthcare Hotel Office Public 

Assembly Restaurant Retail School Warehouse No Prototype Total Rep. by Study

AK 1.3 % 9.0 % 8.7 % 15.6 % 7.6 % 0.9 % 14.4 % 15.9 % 8.7 % 17.9 % 100.0 % 56.8 %

AL 7.1 % 6.3 % 7.6 % 13.3 % 5.7 % 1.5 % 22.0 % 13.6 % 7.5 % 15.4 % 100.0 % 65.2 %

AR 2.0 % 7.8 % 8.1 % 10.9 % 5.7 % 1.3 % 22.9 % 21.8 % 5.7 % 13.7 % 100.0 % 67.1 %

AZ 4.4 % 6.3 % 4.4 % 16.9 % 5.0 % 1.1 % 20.6 % 9.6 % 15.6 % 16.0 % 100.0 % 57.1 %

CA 13.5 % 4.6 % 4.3 % 12.7 % 4.3 % 0.7 % 14.7 % 9.8 % 18.4 % 17.0 % 100.0 % 55.7 %

CO 12.4 % 8.4 % 6.1 % 13.1 % 4.3 % 1.2 % 17.6 % 10.0 % 9.4 % 17.5 % 100.0 % 60.4 %

CT 8.5 % 5.6 % 6.8 % 8.6 % 7.1 % 0.9 % 17.2 % 16.5 % 11.3 % 17.6 % 100.0 % 58.5 %

DC 28.7 % 1.7 % 2.7 % 35.7 % 2.7 % 0.1 % 2.5 % 4.7 % 0.8 % 20.3 % 100.0 % 74.4 %

DE 4.1 % 9.0 % 7.2 % 13.0 % 6.9 % 0.9 % 13.8 % 16.9 % 9.3 % 18.8 % 100.0 % 55.9 %

FL 25.9 % 4.1 % 3.6 % 10.9 % 3.8 % 0.8 % 14.4 % 9.4 % 11.7 % 15.4 % 100.0 % 65.0 %

GA 10.2 % 4.3 % 4.2 % 10.0 % 3.3 % 0.9 % 16.3 % 15.4 % 20.6 % 14.8 % 100.0 % 57.0 %

HI 47.7 % 3.4 % 3.4 % 6.4 % 2.2 % 0.3 % 10.2 % 3.4 % 4.9 % 18.1 % 100.0 % 71.4 %

IA 2.0 % 8.8 % 5.9 % 13.8 % 9.1 % 1.0 % 18.7 % 17.4 % 8.6 % 14.7 % 100.0 % 58.8 %

ID 5.8 % 9.3 % 5.5 % 17.9 % 5.7 % 1.1 % 17.4 % 15.9 % 9.0 % 12.4 % 100.0 % 63.6 %

IL 21.1 % 5.1 % 3.8 % 8.5 % 4.9 % 0.7 % 16.3 % 8.9 % 18.7 % 12.1 % 100.0 % 59.2 %

IN 2.0 % 9.4 % 4.7 % 9.5 % 7.2 % 1.4 % 18.0 % 14.0 % 20.6 % 13.2 % 100.0 % 49.6 %

KS 1.8 % 9.9 % 6.5 % 16.3 % 5.5 % 1.8 % 20.8 % 15.3 % 9.5 % 12.5 % 100.0 % 62.6 %

KY 2.7 % 7.7 % 6.6 % 11.9 % 7.8 % 1.4 % 17.0 % 13.0 % 20.5 % 11.3 % 100.0 % 52.7 %

LA 2.0 % 7.7 % 9.5 % 13.8 % 7.0 % 1.6 % 20.4 % 9.9 % 11.9 % 16.2 % 100.0 % 57.2 %

MA 22.9 % 5.6 % 6.9 % 8.6 % 4.9 % 0.9 % 13.7 % 10.5 % 6.6 % 19.3 % 100.0 % 63.6 %

MD 19.7 % 4.8 % 4.9 % 16.6 % 3.4 % 0.6 % 9.2 % 9.0 % 11.8 % 20.0 % 100.0 % 60.0 %

ME 2.6 % 8.4 % 6.7 % 9.0 % 5.4 % 1.4 % 22.8 % 12.6 % 11.3 % 19.9 % 100.0 % 55.0 %

MI 3.0 % 12.1 % 4.8 % 11.4 % 9.2 % 1.3 % 21.9 % 13.9 % 5.8 % 16.5 % 100.0 % 56.4 %

MN 12.3 % 8.7 % 4.1 % 14.0 % 4.5 % 0.9 % 18.3 % 10.1 % 6.9 % 20.1 % 100.0 % 59.7 %

MO 7.4 % 8.0 % 7.5 % 10.4 % 6.6 % 1.3 % 21.3 % 13.8 % 6.9 % 16.7 % 100.0 % 61.7 %

MS 2.4 % 5.4 % 7.7 % 10.1 % 6.6 % 0.9 % 18.6 % 11.9 % 25.5 % 11.1 % 100.0 % 51.5 %

MT 3.8 % 10.2 % 9.9 % 12.5 % 7.9 % 1.5 % 21.3 % 14.6 % 6.4 % 12.0 % 100.0 % 63.5 %

NC 7.2 % 6.1 % 5.3 % 15.2 % 5.0 % 1.0 % 20.2 % 15.4 % 8.6 % 15.9 % 100.0 % 64.3 %

ND 0.6 % 10.3 % 8.0 % 12.1 % 9.9 % 1.3 % 29.0 % 15.2 % 5.0 % 8.7 % 100.0 % 66.1 %

NE 3.2 % 9.9 % 6.6 % 13.7 % 7.2 % 1.2 % 25.0 % 11.2 % 7.4 % 14.7 % 100.0 % 60.8 %

NH 5.1 % 8.2 % 8.2 % 10.0 % 5.6 % 1.8 % 23.4 % 14.9 % 6.9 % 15.9 % 100.0 % 63.5 %

NJ 16.1 % 4.6 % 5.4 % 7.1 % 4.5 % 0.6 % 14.3 % 15.1 % 17.3 % 14.9 % 100.0 % 58.8 %

NM 2.2 % 6.0 % 10.2 % 15.1 % 8.6 % 1.5 % 18.7 % 18.4 % 7.1 % 12.0 % 100.0 % 66.2 %

NV 16.3 % 3.0 % 16.9 % 9.3 % 6.8 % 0.9 % 13.6 % 5.5 % 9.5 % 18.4 % 100.0 % 62.3 %

NY 38.3 % 5.4 % 6.5 % 11.0 % 3.5 % 0.7 % 12.0 % 7.4 % 4.2 % 11.1 % 100.0 % 75.8 %

OH 2.6 % 10.0 % 3.8 % 10.9 % 5.2 % 1.5 % 20.9 % 18.1 % 13.8 % 13.2 % 100.0 % 57.8 %

OK 1.5 % 10.0 % 6.4 % 9.6 % 11.0 % 1.8 % 17.2 % 14.8 % 11.7 % 16.0 % 100.0 % 51.3 %

OR 14.4 % 10.5 % 4.1 % 10.6 % 4.4 % 0.8 % 15.8 % 7.5 % 13.1 % 18.9 % 100.0 % 53.1 %

PA 6.4 % 8.2 % 6.0 % 10.4 % 5.8 % 0.9 % 16.1 % 15.7 % 15.1 % 15.3 % 100.0 % 55.7 %

RI 14.2 % 3.6 % 11.5 % 15.0 % 4.9 % 1.5 % 16.6 % 11.8 % 6.8 % 14.1 % 100.0 % 70.6 %

SC 14.6 % 5.5 % 4.1 % 11.3 % 4.0 % 1.2 % 19.1 % 16.4 % 8.1 % 15.7 % 100.0 % 66.8 %

SD 0.9 % 7.9 % 5.7 % 17.0 % 8.3 % 0.8 % 22.5 % 17.7 % 5.8 % 13.5 % 100.0 % 64.5 %

TN 6.0 % 6.3 % 4.2 % 14.0 % 4.5 % 1.2 % 21.9 % 11.1 % 16.5 % 14.3 % 100.0 % 58.4 %

TX 7.7 % 6.2 % 4.9 % 11.5 % 4.6 % 1.2 % 18.2 % 17.6 % 14.7 % 13.4 % 100.0 % 61.1 %

UT 7.2 % 6.6 % 3.7 % 15.9 % 5.5 % 0.9 % 16.6 % 14.8 % 14.8 % 14.0 % 100.0 % 59.0 %

VA 15.6 % 4.5 % 6.0 % 16.4 % 4.9 % 0.9 % 13.4 % 10.6 % 8.1 % 19.6 % 100.0 % 62.9 %

VT 16.2 % 9.9 % 9.6 % 11.3 % 7.1 % 0.6 % 6.3 % 13.6 % 8.8 % 16.6 % 100.0 % 57.6 %

WA 18.3 % 5.9 % 4.7 % 13.1 % 4.5 % 0.6 % 13.5 % 9.9 % 10.1 % 19.4 % 100.0 % 60.1 %

WI 7.6 % 12.7 % 4.9 % 13.0 % 6.3 % 1.1 % 20.9 % 9.5 % 7.4 % 16.6 % 100.0 % 57.0 %

WV 2.7 % 9.0 % 6.2 % 8.1 % 4.9 % 1.6 % 27.9 % 20.2 % 7.5 % 12.0 % 100.0 % 66.7 %

WY 0.3 % 6.2 % 14.4 % 5.8 % 11.1 % 0.8 % 13.7 % 22.1 % 5.8 % 19.8 % 100.0 % 57.1 %

Total 13.0 % 6.3 % 5.3 % 12.0 % 5.0 % 1.0 % 16.7 % 12.3 % 12.9 % 15.5 % 100.0 % 60.4 %
110

Table A-5 CO2, CH4, and N2O Emissions Rates Electricity Generation by State 

State

CO2 CH4 N2O CO2 CH4 N2O

(t/GWh) (t/GWh) (t/GWh) State (t/GWh) (t/GWh) (t/GWh)

AK 603.4 57.9 1.9 MT 542.8 30.1 0.4

AL 804.2 42.7 0.5 NC 616.6 30.5 0.2

AR 695.9 58.6 1.7 ND 851.1 40.4 0.2

AZ 746.9 53.2 1.2 NE 851.1 40.4 0.2

CA 450.0 45.8 1.5 NH 550.4 47.0 1.4

CO 938.8 54.0 0.8 NJ 618.7 33.4 0.4

CT 550.4 47.0 1.4 NM 778.5 55.3 1.3

DE 618.7 33.4 0.4 NV 465.6 27.6 0.4

FL 767.5 57.2 1.5 NY 480.7 32.3 0.8

GA 804.2 42.7 0.5 OH 835.7 38.9 0.2

HI 807.1 28.0 0.1 OK 904.8 63.9 1.4

IA 851.1 40.4 0.2 OR 465.6 27.6 0.4

ID 465.6 27.6 0.4 PA 672.9 34.7 0.4

IL 948.3 44.4 0.2 RI 550.4 47.0 1.4

IN 835.7 38.9 0.2 SC 616.6 30.5 0.2

KS 926.0 44.8 0.3 SD 851.1 40.4 0.2

KY 781.9 36.9 0.2 TN 781.9 36.9 0.2

LA 719.2 59.2 1.6 TX 790.9 65.8 1.8

MA 550.4 47.0 1.4 UT 465.6 27.6 0.4

MD 618.7 33.4 0.4 VA 689.6 33.3 0.2

ME 550.4 47.0 1.4 VT 550.4 47.0 1.4

MI 861.4 46.8 0.6 WA 465.6 27.6 0.4

MN 851.1 40.4 0.2 WI 860.7 44.1 0.4

MO 939.4 44.6 0.2 WV 835.7 38.9 0.2

MS 709.8 48.3 1.0 WY 623.7 36.4 0.5
111

B Percentage Changes by Building Type for the Nationwide Adoption 

of the LEC Design 

Table B-1 4-Story Apartment Building Summary Table for LEC and 10-Year 

Study Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -12.7 -31.2 -25.0 -1.7 MT -9.6 -15.2 -14.5 0.6

AL -35.2 -40.3 -42.9 -3.4 NC -13.5 -17.0 -18.1 0.4

AR -29.0 -36.6 -39.4 -1.8 ND -17.5 -30.8 -33.4 -1.0

AZ -26.6 -31.1 -32.4 -1.6 NE -9.8 -16.3 -17.2 0.7

CA -16.1 -22.5 -19.8 0.2 NH -9.5 -15.8 -14.7 -0.3

CO -21.9 -36.2 -37.9 -1.2 NJ -10.3 -17.8 -16.0 0.4

CT -9.5 -18.5 -15.1 -0.1 NM -13.6 -20.0 -20.0 0.5

DE -10.4 -15.0 -16.0 -0.2 NV -14.5 -20.7 -18.8 -0.1

FL -16.6 -17.7 -17.8 -0.3 NY -9.2 -17.5 -13.8 0.0

GA -14.3 -17.7 -18.8 0.4 OH -9.6 -16.0 -17.1 0.5

HI -20.4 -20.4 -20.4 -1.7 OK -27.2 -35.1 -40.8 -1.3

IA -9.8 -15.8 -16.8 0.5 OR -10.0 -15.0 -15.4 1.1

ID -10.2 -14.8 -14.9 0.8 PA -9.5 -14.9 -16.0 0.6

IL -9.4 -17.1 -17.1 0.3 RI -9.2 -15.5 -15.1 0.2

IN -10.1 -16.0 -17.1 0.6 SC -18.0 -22.6 -23.2 -0.1

KS -24.9 -35.3 -39.1 -1.6 SD -21.2 -34.1 -35.9 -1.7

KY -11.5 -15.6 -17.9 0.7 TN -16.1 -20.5 -21.3 -0.1

LA -15.4 -17.6 -18.3 0.5 TX -15.0 -18.6 -18.6 0.0

MA -9.1 -16.8 -14.8 0.1 UT -10.7 -17.6 -15.7 0.7

MD -10.9 -17.1 -16.4 0.2 VA -12.6 -17.0 -18.1 0.5

ME -19.9 -32.9 -31.9 -2.6 VT -9.5 -15.5 -14.6 -0.2

MI -8.5 -15.2 -16.3 0.4 WA -8.8 -12.8 -14.0 1.2

MN -13.8 -18.0 -18.6 0.2 WI -9.5 -15.9 -16.4 0.4

MO -25.4 -33.3 -38.6 -1.0 WV -25.3 -29.8 -38.9 -0.8

MS -35.7 -42.4 -42.6 -3.3 WY -22.7 -36.6 -36.4 -1.4

Avg. -14.8 -21.2 -21.6 -0.1
112

Table B-2 6-Story Apartment Building Summary Table for LEC and 10-Year 

Study Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -12.2 -31.1 -24.8 -1.5 MT -9.5 -15.1 -14.4 0.6

AL -35.6 -41.2 -44.1 -3.5 NC -14.8 -19.2 -20.6 0.2

AR -29.8 -37.9 -40.8 -1.9 ND -17.2 -30.5 -33.1 -0.9

AZ -27.1 -32.5 -34.0 -1.7 NE -11.2 -19.5 -20.5 0.6

CA -18.2 -26.1 -22.8 -0.1 NH -9.3 -15.4 -14.4 -0.3

CO -22.5 -37.7 -39.5 -1.2 NJ -11.4 -20.6 -18.5 0.2

CT -10.6 -21.8 -17.7 -0.4 NM -15.1 -23.0 -23.0 0.3

DE -11.2 -17.0 -18.2 -0.4 NV -14.9 -22.9 -20.5 -0.1

FL -17.5 -18.9 -19.0 -0.4 NY -9.6 -19.4 -15.1 -0.1

GA -15.5 -19.5 -20.9 0.3 OH -10.6 -18.5 -19.9 0.4

HI -20.7 -20.7 -20.7 -1.6 OK -28.1 -36.5 -42.6 -1.5

IA -10.6 -17.6 -18.7 0.5 OR -10.9 -17.1 -17.7 1.0

ID -11.1 -16.5 -16.5 0.8 PA -10.4 -17.1 -18.5 0.5

IL -10.5 -20.0 -20.1 0.1 RI -10.0 -17.9 -17.4 0.0

IN -11.3 -18.7 -20.1 0.5 SC -18.9 -24.4 -25.1 -0.2

KS -25.9 -37.4 -41.4 -1.8 SD -20.6 -33.5 -35.4 -1.5

KY -13.4 -18.6 -21.4 0.5 TN -17.3 -22.9 -23.9 -0.3

LA -16.5 -19.1 -20.0 0.4 TX -16.3 -20.6 -20.6 -0.2

MA -9.8 -19.5 -17.0 0.0 UT -11.9 -20.5 -18.2 0.6

MD -12.1 -19.9 -19.0 0.0 VA -14.4 -20.0 -21.3 0.3

ME -19.3 -32.3 -31.4 -2.4 VT -9.2 -15.1 -14.2 -0.1

MI -8.9 -16.7 -17.9 0.3 WA -9.4 -14.4 -15.8 1.2

MN -13.0 -17.3 -17.9 0.4 WI -9.3 -15.5 -16.0 0.5

MO -26.5 -35.2 -40.9 -1.1 WV -26.2 -31.2 -41.0 -0.8

MS -36.2 -43.3 -43.5 -3.4 WY -22.5 -36.3 -36.2 -1.3

Avg. -9.5 -15.1 -23.3 -0.2
113

Table B-3 4-Story Dormitory Summary Table for LEC and 10-Year Study Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -18.1 -34.8 -29.3 -2.4 MT -12.9 -17.1 -16.6 -1.2

AL -36.7 -41.7 -44.2 -2.9 NC -14.8 -17.7 -18.5 -0.7

AR -28.8 -37.1 -40.0 -4.9 ND -21.6 -33.7 -36.0 0.3

AZ -29.1 -32.1 -32.9 -1.6 NE -11.7 -17.2 -17.9 -0.2

CA -18.2 -22.3 -20.6 -1.3 NH -12.2 -17.0 -16.2 -1.7

CO -24.9 -36.6 -37.9 -4.2 NJ -12.3 -18.6 -17.2 -0.8

CT -11.2 -18.9 -16.1 -1.6 NM -15.3 -19.8 -19.8 -1.6

DE -12.3 -16.3 -17.2 -0.5 NV -17.1 -21.1 -19.9 -1.9

FL -17.4 -18.4 -18.5 -2.1 NY -11.1 -18.2 -15.1 -1.5

GA -15.1 -18.1 -19.1 -1.2 OH -11.2 -16.9 -17.8 -1.2

HI -22.1 -22.1 -22.1 -3.6 OK -27.6 -36.1 -42.2 0.0

IA -11.7 -16.7 -17.5 -0.2 OR -12.7 -16.7 -17.0 -1.0

ID -12.7 -16.4 -16.5 -1.2 PA -11.1 -15.9 -16.8 -0.8

IL -11.1 -17.8 -17.8 -0.3 RI -11.3 -16.7 -16.4 -1.4

IN -11.8 -16.9 -17.9 -0.4 SC -16.9 -21.7 -22.3 -1.3

KS -27.6 -37.1 -40.4 0.3 SD -24.0 -35.7 -37.3 -1.4

KY -12.9 -16.4 -18.3 -1.0 TN -17.3 -20.4 -20.9 -1.1

LA -15.5 -17.8 -18.5 -0.8 TX -15.5 -18.6 -18.7 -0.9

MA -11.1 -17.8 -16.1 -1.3 UT -12.8 -18.2 -16.8 -1.2

MD -12.5 -17.8 -17.2 -0.2 VA -14.3 -17.9 -18.7 -0.7

ME -24.4 -35.6 -34.9 -1.6 VT -11.9 -16.7 -15.9 -1.6

MI -10.7 -16.5 -17.4 -1.2 WA -11.6 -15.0 -16.0 -0.5

MN -19.0 -20.7 -20.9 -1.5 WI -12.0 -17.0 -17.4 -0.8

MO -27.4 -35.0 -39.8 0.2 WV -26.7 -31.0 -38.8 -3.3

MS -39.0 -44.2 -44.4 -1.8 WY -26.9 -38.4 -38.3 -0.9

Avg. -16.9 -22.2 -22.6 -1.2
114

Table B-4 6-Story Dormitory Summary Table for LEC and 10-Year Study Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -11.1 -30.0 -23.7 -2.2 MT -8.6 -13.6 -12.9 0.3

AL -37.9 -43.7 -46.7 -4.9 NC -14.7 -19.1 -20.4 -0.1

AR -30.8 -39.1 -42.1 -2.9 ND -16.6 -28.8 -31.2 -1.6

AZ -28.3 -33.6 -35.1 -2.4 NE -10.9 -18.8 -19.8 0.3

CA -17.9 -26.3 -22.7 -0.4 NH -8.4 -13.8 -12.9 -0.5

CO -20.7 -36.0 -37.9 -1.8 NJ -11.4 -20.4 -18.3 -0.2

CT -10.4 -21.2 -17.2 -0.7 NM -15.2 -22.8 -22.9 -0.1

DE -11.3 -16.9 -18.0 -0.8 NV -14.1 -22.1 -19.6 -0.4

FL -18.4 -20.0 -20.1 -0.9 NY -9.1 -18.3 -14.3 -0.4

GA -15.5 -19.7 -21.2 -0.1 OH -10.3 -17.9 -19.2 0.1

HI -23.0 -23.0 -23.0 -2.5 OK -29.9 -38.5 -44.8 -2.6

IA -10.0 -16.4 -17.4 0.2 OR -10.6 -16.7 -17.1 0.7

ID -10.6 -15.6 -15.7 0.5 PA -10.3 -16.8 -18.0 0.2

IL -10.3 -19.4 -19.4 -0.2 RI -9.7 -17.2 -16.7 -0.3

IN -11.0 -18.1 -19.4 0.2 SC -20.2 -26.0 -26.8 -0.7

KS -24.8 -36.3 -40.4 -2.6 SD -17.3 -30.6 -32.5 -2.0

KY -12.9 -17.9 -20.6 0.2 TN -16.1 -21.9 -22.9 -0.5

LA -16.7 -19.6 -20.6 0.0 TX -16.3 -20.9 -20.9 -0.6

MA -9.5 -18.7 -16.4 -0.3 UT -12.0 -20.1 -18.0 0.3

MD -12.0 -19.7 -18.8 -0.4 VA -14.2 -19.6 -20.8 0.0

ME -18.0 -30.6 -29.7 -3.1 VT -8.2 -13.4 -12.6 -0.3

MI -8.5 -15.9 -17.1 0.1 WA -9.2 -14.1 -15.5 0.9

MN -11.3 -15.2 -15.7 0.2 WI -8.2 -13.7 -14.2 0.2

MO -26.0 -34.9 -40.6 -1.9 WV -24.4 -29.6 -39.1 -1.4

MS -38.2 -45.6 -45.9 -4.7 WY -19.1 -33.4 -33.2 -1.8

Avg. -15.2 -22.4 -22.8 -0.6
115

Table B-5 15-Story Hotel Building Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -6.9 -23.5 -18.0 -1.8 MT -9.4 -11.5 -11.3 0.4

AL -30.3 -36.2 -39.2 -3.0 NC -14.9 -18.4 -19.4 0.3

AR -21.5 -32.1 -36.0 -1.6 ND -10.0 -20.8 -22.8 -1.1

AZ -23.1 -26.4 -27.3 -1.0 NE -12.7 -18.9 -19.7 0.6

CA -18.2 -24.5 -21.8 0.0 NH -8.9 -11.2 -10.8 -0.2

CO -16.0 -28.8 -30.3 -1.1 NJ -13.1 -20.2 -18.6 0.1

CT -12.7 -21.6 -18.3 -0.5 NM -15.7 -21.1 -21.1 0.4

DE -13.1 -17.6 -18.5 -0.6 NV -8.8 -14.7 -13.0 0.7

FL -16.7 -18.8 -19.0 -0.1 NY -11.2 -18.0 -15.0 -0.2

GA -14.5 -18.5 -19.9 0.4 OH -11.8 -18.1 -19.2 0.4

HI -18.0 -18.1 -18.1 -0.6 OK -19.7 -29.9 -37.5 -1.2

IA -11.0 -15.3 -16.0 0.5 OR -13.8 -18.4 -18.8 0.9

ID -12.3 -15.9 -15.9 0.7 PA -11.8 -17.1 -18.2 0.4

IL -11.8 -19.2 -19.2 0.2 RI -12.1 -18.1 -17.7 -0.1

IN -12.3 -18.1 -19.2 0.5 SC -8.5 -14.6 -15.4 0.9

KS -19.7 -29.4 -32.9 -1.5 SD -11.8 -21.8 -23.2 -1.3

KY -13.7 -17.6 -19.8 0.6 TN -9.6 -13.6 -14.3 0.8

LA -14.5 -18.1 -19.3 0.6 TX -14.9 -19.6 -19.6 0.0

MA -11.8 -19.3 -17.4 -0.1 UT -14.2 -20.2 -18.6 0.6

MD -13.4 -19.4 -18.7 -0.1 VA -14.9 -18.8 -19.8 0.4

ME -14.0 -23.1 -22.5 -2.3 VT -9.0 -11.3 -11.0 -0.1

MI -10.1 -15.5 -16.4 0.2 WA -12.3 -16.2 -17.2 1.1

MN -6.8 -6.8 -6.8 0.9 WI -8.9 -11.2 -11.4 0.4

MO -19.8 -27.5 -32.6 -0.9 WV -18.9 -23.4 -32.3 -0.6

MS -34.4 -37.0 -37.1 -2.8 WY -13.8 -24.7 -24.6 -1.3

Avg. -13.9 -19.6 -20.0 -0.1
116

Table B-6 2-Story High School Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -7.7 -17.8 -14.0 -1.6 MT -9.7 -13.9 -13.3 -0.6

AL -23.6 -29.4 -32.7 -3.3 NC -10.5 -16.2 -18.1 -1.1

AR -16.5 -25.0 -28.5 -1.8 ND -11.1 -18.9 -20.8 -0.9

AZ -21.5 -27.4 -29.2 -2.8 NE -5.8 -15.0 -16.4 -0.6

CA -13.7 -23.4 -19.2 -1.8 NH -5.7 -12.3 -11.1 -1.5

CO -10.6 -23.1 -25.0 -1.9 NJ -6.6 -17.8 -15.0 -1.5

CT -5.3 -17.9 -12.8 -1.9 NM -9.6 -19.8 -19.9 -1.0

DE -6.4 -13.3 -14.8 -1.8 NV -9.5 -18.2 -15.4 -1.5

FL -21.2 -23.4 -23.7 -1.9 NY -6.2 -16.7 -11.8 -1.6

GA -12.6 -18.2 -20.3 -1.6 OH -5.6 -14.2 -15.8 -0.8

HI -26.7 -26.7 -26.7 -4.2 OK -15.0 -22.8 -29.7 -1.3

IA -6.1 -13.8 -15.2 -0.8 OR -4.9 -11.5 -12.1 0.0

ID -6.0 -11.8 -11.9 -0.2 PA -5.4 -12.7 -14.3 -0.6

IL -5.6 -16.4 -16.5 -1.1 RI -5.0 -13.7 -13.0 -0.9

IN -6.4 -14.8 -16.6 -0.8 SC -13.8 -19.8 -20.6 -1.3

KS -13.7 -23.4 -27.7 -1.5 SD -10.9 -20.0 -21.7 -1.8

KY -8.0 -14.1 -17.8 -0.9 TN -12.9 -19.9 -21.3 -1.7

LA -15.4 -19.5 -21.0 -0.8 TX -14.7 -21.0 -21.1 -1.7

MA -4.6 -15.2 -12.3 -1.1 UT -5.9 -15.6 -12.8 -0.8

MD -7.2 -16.9 -15.6 -1.7 VA -9.2 -16.4 -18.3 -0.6

ME -10.7 -18.9 -18.3 -1.9 VT -5.9 -12.1 -11.0 -1.4

MI -4.6 -12.7 -14.2 -0.8 WA -4.2 -9.4 -10.9 0.2

MN -9.2 -14.1 -14.9 -1.1 WI -5.9 -12.7 -13.4 -1.1

MO -14.3 -21.7 -27.7 -1.4 WV -13.3 -17.1 -26.4 -1.3

MS -26.7 -33.1 -33.4 -3.4 WY -11.5 -21.2 -21.1 -1.3

Avg. -10.6 -18.0 -18.5 -1.3
117

Table B-7 8-Story Office Building Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -21.3 -25.8 -24.6 0.0 MT -16.9 -18.1 -18.0 -1.5

AL -31.7 -32.2 -32.4 -0.7 NC -20.2 -20.9 -21.1 -1.9

AR -30.0 -31.4 -31.9 -5.2 ND -26.0 -28.1 -28.4 1.3

AZ -28.1 -28.0 -28.0 -2.3 NE -18.5 -21.2 -21.5 -2.2

CA -21.4 -21.9 -21.8 -2.8 NH -16.9 -18.2 -18.1 -2.2

CO -28.3 -29.7 -29.9 -5.1 NJ -19.5 -21.4 -21.1 -2.5

CT -18.3 -21.3 -20.5 -2.7 NM -21.4 -22.5 -22.5 -2.8

DE -19.7 -21.1 -21.3 -3.2 NV -23.0 -23.4 -23.3 -3.6

FL -20.1 -20.2 -20.2 -2.6 NY -17.0 -20.1 -19.0 -2.5

GA -19.5 -20.2 -20.4 -1.7 OH -17.9 -20.6 -20.9 -2.2

HI -21.3 -21.3 -21.3 -3.6 OK -31.2 -32.9 -34.0 0.9

IA -17.3 -19.6 -19.8 -1.5 OR -20.9 -22.0 -22.0 -3.0

ID -19.3 -20.4 -20.4 -2.4 PA -18.0 -20.3 -20.6 -2.4

IL -17.8 -21.0 -21.0 -2.2 RI -18.9 -21.0 -20.9 -2.4

IN -18.5 -20.8 -21.1 -2.0 SC -21.7 -21.9 -22.0 -2.2

KS -32.5 -33.1 -33.3 0.3 SD -26.8 -28.4 -28.6 -0.5

KY -19.5 -20.8 -21.4 -2.4 TN -23.4 -22.7 -22.6 -3.0

LA -19.9 -20.2 -20.3 -1.8 TX -19.9 -20.5 -20.5 -2.6

MA -18.3 -21.1 -20.6 -2.5 UT -20.7 -22.5 -22.1 -2.6

MD -19.7 -21.4 -21.2 -2.9 VA -20.8 -21.7 -21.9 -2.2

ME -28.1 -29.2 -29.1 0.0 VT -16.5 -18.0 -17.8 -2.0

MI -16.7 -19.6 -19.8 -2.2 WA -20.0 -21.1 -21.3 -2.3

MN -21.4 -19.8 -19.6 -1.3 WI -16.4 -18.0 -18.1 -1.2

MO -32.3 -32.5 -32.6 0.4 WV -30.1 -30.4 -30.3 -4.8

MS -32.4 -32.0 -31.9 1.1 WY -29.2 -30.1 -30.0 0.7

Avg. -21.5 -22.8 -22.8 -2.1
118

Table B-8 16-Story Office Building Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -8.1 -14.9 -12.9 -0.2 MT -11.7 -12.5 -12.5 0.4

AL -23.3 -25.1 -26.0 -1.0 NC -17.2 -19.1 -19.6 0.4

AR -18.2 -23.8 -25.7 0.0 ND -9.9 -13.5 -14.1 0.4

AZ -19.6 -20.5 -20.8 0.0 NE -15.2 -20.2 -20.7 0.8

CA -19.8 -21.8 -21.0 -0.1 NH -11.3 -12.3 -12.2 -0.6

CO -15.7 -21.2 -21.7 0.1 NJ -16.0 -21.0 -20.1 -0.1

CT -15.2 -21.6 -19.6 -0.9 NM -18.9 -21.7 -21.7 0.3

DE -16.0 -19.4 -19.9 -1.0 NV -12.5 -16.0 -15.1 0.7

FL -17.6 -18.5 -18.5 -0.2 NY -13.9 -18.7 -16.9 -0.6

GA -16.5 -18.4 -19.1 0.5 OH -14.4 -19.5 -20.2 0.5

HI -16.4 -16.4 -16.4 -0.6 OK -17.3 -23.0 -26.9 0.3

IA -13.0 -16.2 -16.6 0.6 OR -17.8 -20.9 -21.1 1.0

ID -15.3 -17.7 -17.8 0.9 PA -14.4 -18.9 -19.6 0.4

IL -13.9 -19.8 -19.8 0.2 RI -15.3 -20.0 -19.7 -0.3

IN -15.0 -19.7 -20.4 0.6 SC -12.1 -15.5 -15.9 1.0

KS -17.1 -21.6 -23.1 0.3 SD -10.1 -13.2 -13.6 0.2

KY -16.2 -19.3 -20.7 0.7 TN -12.3 -15.0 -15.4 0.8

LA -16.6 -18.3 -18.8 0.7 TX -16.8 -19.1 -19.1 -0.1

MA -14.4 -20.2 -19.0 -0.3 UT -17.5 -21.7 -20.8 0.6

MD -16.0 -20.1 -19.7 -0.3 VA -18.0 -20.6 -21.1 0.4

ME -13.9 -15.9 -15.8 -0.7 VT -11.3 -12.3 -12.2 -0.4

MI -12.6 -16.9 -17.5 0.2 WA -16.2 -19.1 -19.8 1.4

MN -8.7 -7.8 -7.7 1.0 WI -10.9 -11.9 -12.0 0.3

MO -16.3 -20.0 -22.2 0.9 WV -16.9 -19.1 -23.0 0.9

MS -27.3 -24.8 -24.7 -0.5 WY -12.8 -16.2 -16.1 0.1

Avg. -15.3 -18.3 -18.5 0.3
119

Table B-9 1-Story Retail Store Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -26.3 -27.3 -26.8 -0.2 MT -16.0 -17.7 -17.5 0.1

AL -35.1 -35.6 -35.9 -0.9 NC -15.8 -17.2 -17.6 0.1

AR -29.8 -31.8 -32.5 -1.7 ND -31.8 -33.4 -33.7 0.6

AZ -31.6 -32.4 -32.6 -1.8 NE -12.5 -16.8 -17.2 0.8

CA -16.1 -17.8 -17.1 0.0 NH -15.9 -17.8 -17.5 -0.9

CO -28.4 -32.0 -32.4 -2.0 NJ -13.9 -17.4 -16.7 0.1

CT -12.3 -16.9 -15.5 -1.7 NM -15.6 -18.9 -18.9 0.1

DE -14.2 -16.7 -17.1 -0.8 NV -21.0 -21.9 -21.7 -0.6

FL -17.9 -18.2 -18.2 -0.7 NY -12.4 -16.4 -14.9 -0.6

GA -15.5 -16.5 -16.8 0.5 OH -12.5 -16.1 -16.6 -0.5

HI -22.3 -22.3 -22.3 -3.1 OK -30.5 -32.6 -34.0 1.9

IA -14.3 -17.2 -17.6 0.6 OR -13.2 -15.3 -15.4 0.8

ID -14.2 -16.3 -16.3 1.2 PA -12.3 -15.4 -15.9 0.1

IL -12.5 -16.9 -16.9 -0.4 RI -12.4 -15.8 -15.6 -1.5

IN -13.5 -16.8 -17.4 0.5 SC -20.2 -20.5 -20.5 0.2

KS -30.6 -33.9 -35.1 1.0 SD -29.9 -33.5 -34.0 -0.9

KY -14.9 -17.2 -18.3 0.5 TN -23.1 -22.6 -22.5 -0.4

LA -15.0 -15.5 -15.7 0.7 TX -15.3 -16.5 -16.5 0.0

MA -11.8 -16.1 -15.2 0.1 UT -13.0 -17.3 -16.3 1.2

MD -14.3 -17.3 -17.0 -0.1 VA -16.1 -18.2 -18.7 0.5

ME -31.7 -33.2 -33.1 -1.2 VT -15.7 -17.5 -17.3 -0.8

MI -12.6 -16.0 -16.4 -0.3 WA -12.3 -13.9 -14.3 1.1

MN -27.3 -23.9 -23.5 -0.8 WI -15.9 -18.0 -18.1 -1.1

MO -31.3 -33.5 -34.8 1.7 WV -30.7 -31.6 -32.9 -1.8

MS -40.6 -38.8 -38.8 -0.3 WY -30.5 -34.0 -34.0 0.4

Avg. -18.9 -20.9 -21.0 -0.1
120

Table B-10 1-Story Restaurant Summary Table for LEC and 10-Year Study 

Period 

State Percentage Change State Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -33.4 -40.1 -37.9 1.0 MT -24.1 -28.9 -28.4 -1.4

AL -43.9 -46.5 -47.7 -3.4 NC -30.2 -33.0 -33.8 -4.8

AR -39.8 -44.8 -46.5 -10.3 ND -41.8 -44.2 -44.6 -0.2

AZ -41.4 -43.6 -44.2 -5.2 NE -24.2 -32.6 -33.5 -3.9

CA -34.1 -37.5 -36.2 -5.2 NH -24.3 -29.0 -28.3 -4.6

CO -40.2 -46.3 -47.0 -7.4 NJ -27.3 -34.1 -32.8 -6.3

CT -24.1 -33.6 -30.6 -4.4 NM -31.4 -36.6 -36.6 -4.3

DE -27.7 -32.2 -33.0 -8.5 NV -35.1 -38.6 -37.7 -6.0

FL -30.5 -31.5 -31.6 -5.3 NY -21.7 -31.5 -27.7 -4.3

GA -30.0 -32.7 -33.6 -4.9 OH -23.3 -31.4 -32.6 -3.4

HI -34.8 -34.8 -34.8 -6.3 OK -39.7 -45.1 -48.8 -3.1

IA -23.7 -30.3 -31.2 -4.4 OR -28.5 -33.0 -33.4 -4.5

ID -26.0 -30.8 -30.9 -2.7 PA -23.7 -30.4 -31.6 -3.4

IL -23.3 -32.6 -32.6 -4.5 RI -25.0 -31.8 -31.4 -3.8

IN -24.8 -31.9 -33.1 -4.3 SC -32.0 -34.7 -35.1 -4.2

KS -40.8 -46.4 -48.3 -1.2 SD -39.0 -43.6 -44.2 -3.0

KY -27.9 -32.3 -34.3 -5.4 TN -32.9 -35.6 -36.1 -7.7

LA -29.3 -31.3 -31.9 -6.0 TX -29.8 -33.2 -33.2 -5.9

MA -23.8 -32.5 -30.7 -3.7 UT -27.1 -34.7 -32.9 -3.8

MD -27.7 -33.5 -32.9 -9.0 VA -30.3 -34.0 -34.8 -5.4

ME -43.6 -45.6 -45.5 -2.6 VT -23.6 -28.5 -27.9 -4.3

MI -22.1 -30.3 -31.4 -3.0 WA -26.4 -30.6 -31.6 -3.9

MN -37.9 -36.3 -36.1 -5.0 WI -23.6 -28.7 -29.1 -3.3

MO -39.1 -43.9 -46.8 -3.3 WV -39.3 -41.8 -45.3 -6.4

MS -46.0 -47.7 -47.7 -1.9 WY -42.3 -46.2 -46.1 1.3

Avg. -30.7 -35.4 -35.6 -4.2
121

C Total Changes from Nationwide Adoption of the LEC Design 

Table C-1 Total Reductions by State for Adoption of the LEC Design, 10-Year 

State Code Average Annual New Floor Area

1000 m2(1000 ft2)

Energy Use 

(GWh)

Energy Costs 

($million)

Carbon 

(1000 tCO2e)

LCC 

($million)

FL 2007 16 542 (178 061) 3790.5 333.0 3230.0 151.3

TX 2007 14 446 (155 495) 2831.6 235.0 2630.0 106.8

CA 2007 14 492 (155 996) 2543.2 306.0 1146.0 124.9

AZ 1999 4758 (51 214) 1857.5 136.0 1255.0 79.1

GA 2007 7240 (77 934) 1348.0 103.0 1018.0 28.5

IL 2007 6929 (74 579) 1212.7 124.0 1344.0 31.4

CO 2001 3292 (35 437) 1112.9 72.7 1126.0 59.7

AL 1999 2254 (24 266) 1050.6 84.9 908.8 37.0

NY 2007 6071 (65 346) 1037.6 133.0 560.8 37.1

MO None 2358 (25 383) 984.7 56.9 1001.0 2.7

VA 2007 4499 (48 426) 871.3 60.5 695.0 14.0

NC 2007 4437 (47 758) 827.9 56.2 585.0 20.3

OH 2007 4907 (52 814) 826.8 74.1 837.6 33.9

MN 2004 2329 (25 068) 816.7 33.5 443.8 12.4

TN 2004 3272 (35 219) 807.8 58.7 626.8 28.1

PA 2007 4661 (50 170) 764.9 63.9 628.9 18.2

NV 2004 3516 (37 844) 709.0 59.7 327.2 17.9

MS 1999 1251 (13 465) 689.6 46.3 465.2 14.8

IN 2007 3663 (39 425) 656.9 49.8 652.7 13.3

MD 2007 3385 (36 433) 622.2 62.4 448.9 28.8

OK 1999 1590 (17 115) 598.1 35.4 678.9 0.7

SC 2004 2718 (29 257) 594.5 43.8 412.4 12.2

NJ 2007 3476 (37 421) 581.6 72.7 436.8 20.8

WA 2007 3710 (39 937) 525.0 32.3 266.7 -11.5

MI 2007 2964 (31 905) 511.9 40.4 490.9 17.0

WI 2007 2386 (25 679) 491.0 33.2 383.7 14.8

KS None 1077 (11 590) 438.6 28.6 436.0 2.3

AR 2001 1186 (12 762) 426.1 28.6 372.7 20.4

MA 2007 2579 (27 760) 403.8 56.0 277.4 12.8

KY 2007 1956 (21 050) 378.0 24.6 341.2 9.8

LA 2007 1700 (18 294) 324.6 20.8 269.7 3.2

UT 2007 1718 (18 492) 286.6 18.8 144.3 5.4

IA 2007 1447 (15 573) 283.7 17.6 256.4 4.0

OR 2007 1745 (18 788) 261.4 17.4 146.1 -0.4

CT 2007 1445 (15 549) 232.0 35.1 160.6 19.7

ME None 497 (5349) 216.6 18.0 113.3 6.4

WV 2001 479 (5159) 177.2 9.7 161.3 7.1

NE 2007 920 (9900) 170.8 11.1 166.6 1.4

NM 2007 817 (8790) 153.7 11.7 146.0 5.5

ID 2007 802 (8629) 139.9 7.6 69.9 1.5

HI 2004 536 (5773) 138.4 23.9 123.8 13.9

SD None 303 (3262) 122.3 6.5 98.2 2.4

NH 2007 553 (5948) 108.0 10.9 59.2 5.8

ND None 229 (2464) 104.5 4.8 75.8 0.0

AK 1999 290 (3116) 99.4 9.8 58.4 2.4

WY 1999 230 (2477) 76.6 5.3 45.3 0.7

DE 2007 344 (3700) 60.1 6.5 45.1 4.5

RI 2007 335 (3604) 55.3 6.6 37.5 3.1

MT 2007 238 (2562) 52.5 2.9 24.1 0.5

VT 2007 200 (2147) 37.3 3.4 20.7 1.4
122

Table C-2 Energy Use Reduction per Unit of Floor Area from Adoption of the LEC

Design, 10-Year 

State Code Average Annual New Floor Area

1000 m2(1000 ft2)

Energy Savings 

(GWh)

kWh/m2kWh/ft2

MS None 1251 (13 465) 689.6 551 51

AL None 2254 (24 266) 1050.6 466 43

ND None 229 (2464) 104.5 456 42

ME None 497 (5349) 216.6 436 40

MO None 2358 (25 383) 984.7 418 39

KS None 1077 (11 590) 438.6 407 38

SD None 303 (3262) 122.3 404 37

AZ None 4758 (51 214) 1857.5 390 36

OK None 1590 (17 115) 598.1 376 35

WV 2001 479 (5159) 177.2 370 34

AR 2001 1186 (12 762) 426.1 359 33

MN 2004 2329 (25 068) 816.7 351 33

AK None 290 (3116) 99.4 343 32

CO 2001 3292 (35 437) 1112.9 338 31

WY None 230 (2477) 76.6 333 31

HI 2004 536 (5773) 138.4 258 24

TN 2004 3272 (35 219) 807.8 247 23

FL 2007 16 542 (178 061) 3790.5 229 21

MT 2007 238 (2562) 52.5 221 20

SC 2004 2718 (29 257) 594.5 219 20

NV 2004 3516 (37 844) 709 202 19

WI 2007 2386 (25 679) 491 206 19

IA 2007 1447 (15 573) 283.7 196 18

KY 2007 1956 (21 050) 378 193 18

LA 2007 1700 (18 294) 324.6 191 18

NH 2007 553 (5948) 108 195 18

TX 2007 14 446 (155 495) 2831.6 196 18

VA 2007 4499 (48 426) 871.3 194 18

GA 2007 7240 (77 934) 1348 186 17

IN 2007 3663 (39 425) 656.9 179 17

MD 2007 3385 (36 433) 622.2 184 17

NC 2007 4437 (47 758) 827.9 187 17

NE 2007 920 (9900) 170.8 186 17

NM 2007 817 (8790) 153.7 188 17

VT 2007 200 (2147) 37.3 187 17

CA 2007 14 492 (155 996) 2543.2 175 16

DE 2007 344 (3700) 60.1 175 16

ID 2007 802 (8629) 139.9 174 16

IL 2007 6929 (74 579) 1212.7 175 16

MI 2007 2964 (31 905) 511.9 173 16

NJ 2007 3476 (37 421) 581.6 167 16

NY 2007 6071 (65 346) 1037.6 171 16

OH 2007 4907 (52 814) 826.8 168 16

MA 2007 2579 (27 760) 403.8 157 15

PA 2007 4661 (50 170) 764.9 164 15

RI 2007 335 (3604) 55.3 165 15

UT 2007 1718 (18 492) 286.6 167 15

CT 2007 1445 (15 549) 232 161 15

OR 2007 1745 (18 788) 261.4 150 14

WA 2007 3710 (39 937) 525 142 13
123

Table C-3 Life-Cycle Cost Reductions per Unit of New Floor Area from Adoption 

of the LEC Design, 10-Year 

State Code kWh/m2 LCC Savings 

($million)

LCC Savings 

($/m2)

LCC Savings 

($/ft2)

HI 2004 258 13.9 25.93 2.41

CO 2001 338 59.7 18.13 1.68

AR 2001 359 20.4 17.20 1.60

AZ 1999 390 79.1 16.62 1.54

AL 1999 466 37.0 16.42 1.53

WV 2001 370 7.1 14.82 1.38

CT 2007 161 19.7 13.63 1.27

DE 2007 175 4.5 13.08 1.22

ME None 436 6.4 12.88 1.20

MS 1999 551 14.8 11.83 1.10

NH 2007 195 5.8 10.49 0.97

RI 2007 165 3.1 9.25 0.86

FL 2007 229 151.3 9.15 0.85

CA 2007 175 124.9 8.62 0.80

TN 2004 247 28.1 8.59 0.80

MD 2007 184 28.8 8.51 0.79

AK 1999 343 2.4 8.28 0.77

SD None 404 2.4 7.92 0.74

TX 2007 196 106.8 7.39 0.69

VT 2007 187 1.4 7.00 0.65

OH 2007 168 33.9 6.91 0.64

NM 2007 188 5.5 6.73 0.63

WI 2007 206 14.8 6.20 0.58

NY 2007 171 37.1 6.11 0.57

NJ 2007 167 20.8 5.98 0.56

MI 2007 173 17.0 5.74 0.53

MN 2004 351 12.4 5.32 0.49

NV 2004 202 17.9 5.09 0.47

KY 2007 193 9.8 5.01 0.47

MA 2007 157 12.8 4.96 0.46

NC 2007 187 20.3 4.58 0.43

IL 2007 175 31.4 4.53 0.42

SC 2004 219 12.2 4.49 0.42

GA 2007 186 28.5 3.94 0.37

PA 2007 164 18.2 3.90 0.36

IN 2007 179 13.3 3.63 0.34

UT 2007 167 5.4 3.14 0.29

VA 2007 194 14.0 3.11 0.29

WY 1999 333 0.7 3.04 0.28

IA 2007 196 4.0 2.76 0.26

KS None 407 2.3 2.14 0.20

MT 2007 221 0.5 2.10 0.20

LA 2007 191 3.2 1.88 0.17

ID 2007 174 1.5 1.87 0.17

NE 2007 186 1.4 1.52 0.14

MO None 418 2.7 1.15 0.11

OK 1999 376 0.7 0.44 0.04

ND None 456 0.0 0.00 0.00

OR 2007 150 -0.4 -0.23 -0.02

WA 2007 142 -11.5 -3.10 -0.29
124

Table C-4 Energy Cost Reduction per kWh of Energy Use Reduction from 

Adoption of the LEC Design, 10-Year 

State Code Offset*

(%)

Electricity Rate

($/kWh)

Natural Gas Rate

($/kWh)

Energy Cost Reduction

($/kWh)

HI 2004 0.0% 0.22 0.09 $0.17 

CT 2007 18.5% 0.17 0.03 $0.15 

MA 2007 18.0% 0.15 0.04 $0.14 

NJ 2007 17.4% 0.14 0.03 $0.13 

NY 2007 7.6% 0.16 0.03 $0.13 

CA 2007 13.0% 0.13 0.02 $0.12 

RI 2007 16.8% 0.14 0.04 $0.12 

DE 2007 17.4% 0.12 0.05 $0.11 

AK 1999 -24.9% 0.14 0.03 $0.10 

IL 2007 11.6% 0.11 0.03 $0.10 

MD 2007 13.3% 0.12 0.03 $0.10 

NH 2007 -20.4% 0.15 0.04 $0.10 

FL 2007 4.0% 0.11 0.03 $0.09 

OH 2007 15.3% 0.10 0.03 $0.09 

VT 2007 -18.6% 0.13 0.04 $0.09 

AL 1999 1.8% 0.10 0.04 $0.08 

GA 2007 10.4% 0.09 0.03 $0.08 

IN 2007 13.6% 0.08 0.03 $0.08 

ME None -27.5% 0.13 0.04 $0.08 

MI 2007 3.7% 0.09 0.03 $0.08 

NM 2007 16.0% 0.08 0.02 $0.08 

NV 2004 1.1% 0.11 0.03 $0.08 

PA 2007 17.2% 0.10 0.03 $0.08 

TX 2007 9.2% 0.10 0.02 $0.08 

AR 2001 17.2% 0.08 0.03 $0.07 

AZ 1999 2.2% 0.09 0.04 $0.07 

CO 2001 8.6% 0.08 0.02 $0.07 

KS None 2.6% 0.08 0.03 $0.07 

KY 2007 11.1% 0.08 0.03 $0.07 

MS 1999 -20.7% 0.10 0.03 $0.07 

NC 2007 11.3% 0.08 0.03 $0.07 

OR 2007 18.8% 0.07 0.03 $0.07 

SC 2004 9.1% 0.09 0.03 $0.07 

TN 2004 -9.4% 0.10 0.03 $0.07 

UT 2007 21.7% 0.07 0.02 $0.07 

VA 2007 12.4% 0.08 0.03 $0.07 

WI 2007 -25.9% 0.10 0.03 $0.07 

WY 1999 6.9% 0.07 0.02 $0.07 

IA 2007 -1.0% 0.08 0.02 $0.06 

LA 2007 7.7% 0.08 0.03 $0.06 

MO None 3.0% 0.07 0.03 $0.06 

MT 2007 -38.9% 0.08 0.03 $0.06 

NE 2007 9.6% 0.07 0.02 $0.06 

OK 1999 17.2% 0.07 0.03 $0.06 

WA 2007 19.4% 0.07 0.04 $0.06 

ID 2007 8.4% 0.06 0.03 $0.05 

ND None -33.0% 0.07 0.02 $0.05 

SD None -14.6% 0.07 0.02 $0.05 

WV 2001 3.9% 0.07 0.04 $0.05 

MN 2004 -121.2% 0.08 0.02 $0.04 
125

Table C-5 Carbon Reduction per GWh of Energy Use Reduction from Adoption of 

the LEC Design, 10-Year 

State Code Offset*

(%)

CO2e Emissions Rate 

for Electricity

(t/GWh)

CO2e Emissions Rate 

for Natural Gas

(t/GWh)

CO2e 

Reduction

(t/GWh)

OK 1999 17.2% 970.1 241 1135

IL 2007 11.6% 992.9 241 1108

MO None 3.0% 984.2 241 1016

OH 2007 15.3% 874.8 241 1013

CO 2001 8.6% 993.6 241 1012

IN 2007 13.6% 874.8 241 994

KS None 2.6% 971.1 241 994

NE 2007 9.6% 891.8 241 975

MI 2007 3.7% 908.8 241 959

NM 2007 16.0% 835.1 241 950

TX 2007 9.2% 858.4 241 929

WV 2001 3.9% 874.8 241 910

IA 2007 -1.0% 891.8 241 904

KY 2007 11.1% 819.0 241 903

HI 2004 0.0% 835.2 241 895

AR 2001 17.2% 756.1 241 875

AL 1999 1.8% 847.4 241 865

FL 2007 4.0% 826.1 241 852

LA 2007 7.7% 780.0 241 831

PA 2007 17.2% 708.0 241 822

SD None -14.6% 891.8 241 803

VA 2007 12.4% 723.1 241 798

WI 2007 -25.9% 905.1 241 781

TN 2004 -9.4% 819.0 241 776

GA 2007 10.4% 847.4 241 755

NJ 2007 17.4% 652.5 241 751

DE 2007 17.4% 652.5 241 750

ND None -33.0% 891.8 241 725

MD 2007 13.3% 652.5 241 721

NC 2007 11.3% 647.3 241 707

SC 2004 9.1% 647.3 241 694

CT 2007 18.5% 598.8 241 692

MA 2007 18.0% 598.8 241 687

RI 2007 16.8% 598.8 241 678

AZ 1999 2.2% 801.4 241 675

MS 1999 -20.7% 759.1 241 675

WY 1999 6.9% 660.7 241 591

AK 1999 -24.9% 663.3 241 588

OR 2007 18.8% 493.6 241 559

VT 2007 -18.6% 598.8 241 555

NH 2007 -20.4% 598.8 241 548

MN 2004 -121.2% 891.8 241 543

NY 2007 7.6% 513.7 241 540

ME None -27.5% 598.8 241 523

WA 2007 19.4% 493.6 241 508

UT 2007 21.7% 493.6 241 503

ID 2007 8.4% 493.6 241 500

NV 2004 1.1% 493.6 241 461

MT 2007 -38.9% 573.3 241 459

CA 2007 13.0% 497.3 241 450
126
127

D Percentage Changes by Building Type for the Nationwide Adoption 

of the ASHRAE 90.1-2007 Design 

Table D-1 4-Story Apartment Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -5.6 -20.2 -15.3 -2.3 MS -25.5 -29.7 -29.9 -3.6

AL -24.3 -27.9 -29.8 -3.6 ND -8.5 -18.8 -20.9 -1.6

AR -18.7 -24.5 -26.6 -2.5 NV -4.3 -3.7 -3.9 -0.4

AZ -14.3 -15.9 -16.3 -1.8 OK -17.4 -23.5 -28.0 -2.0

CO -12.7 -22.0 -23.1 -1.9 SC -4.7 -6.1 -6.3 -0.6

HI -2.7 -2.7 -2.7 -0.5 SD -12.5 -21.9 -23.3 -2.2

KS -15.7 -23.0 -25.6 -2.2 TN -3.7 -3.4 -3.3 -0.4

ME -11.5 -21.3 -20.6 -2.8 WV -15.9 -19.0 -25.3 -1.7

MN -4.9 -3.5 -3.3 -0.5 WY -13.7 -24.0 -23.9 -2.0

MO -16.0 -21.6 -25.3 -1.8 Avg. -11.4 -16.7 -17.4 -1.7

Table D-2 6-Story Apartment Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -5.5 -20.3 -15.4 -2.2 MS -25.3 -29.5 -29.7 -3.6

AL -23.7 -27.6 -29.5 -3.6 ND -8.5 -18.8 -20.8 -1.6

AR -18.4 -24.3 -26.4 -2.5 NV -3.7 -3.2 -3.4 -0.3

AZ -13.6 -15.3 -15.7 -1.7 OK -17.0 -23.3 -27.9 -2.1

CO -12.4 -21.7 -22.8 -1.8 SC -4.1 -5.9 -6.1 -0.5

HI -2.5 -2.5 -2.5 -0.4 SD -12.1 -21.6 -22.9 -2.1

KS -15.4 -22.7 -25.3 -2.3 TN -3.1 -2.9 -2.8 -0.3

ME -11.2 -21.0 -20.3 -2.7 WV -15.4 -18.6 -24.8 -1.6

MN -4.4 -3.1 -2.9 -0.4 WY -13.3 -23.7 -23.6 -1.9

MO -15.7 -21.2 -24.9 -1.8 Avg. -11.0 -16.3 -17.1 -1.6
128

Table D-3 4-Story Dormitory Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -6.5 -21.1 -16.3 -1.8 MS -29.2 -32.0 -32.1 -1.0

AL -25.6 -29.4 -31.2 -1.2 ND -9.3 -20.2 -22.2 1.2

AR -17.7 -24.5 -26.9 -5.1 NV -5.0 -3.5 -3.9 -0.7

AZ -16.4 -16.9 -17.0 -0.1 OK -16.8 -24.2 -29.4 -0.3

CO -13.4 -21.8 -22.8 -2.9 SC -2.0 -4.4 -4.7 -0.5

HI -2.9 -2.9 -2.9 -0.8 SD -13.1 -22.7 -24.0 -1.2

KS -17.2 -24.4 -26.9 0.3 TN -3.6 -2.8 -2.7 -0.7

ME -13.1 -22.5 -21.9 -0.2 WV -16.2 -19.4 -25.1 -2.2

MN -7.3 -4.7 -4.3 -0.7 WY -14.9 -24.6 -24.5 0.4

MO -16.9 -22.6 -26.3 -0.1 Avg. -12.3 -17.2 -17.9 -0.9

Table D-4 6-Story Dormitory Summary Table for ASHRAE 90.1-2007 and 10-Year 

Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -5.1 -19.9 -14.9 -2.6 MS -27.7 -32.2 -32.4 -4.5

AL -26.5 -30.5 -32.5 -4.6 ND -9.0 -18.3 -20.2 -2.1

AR -19.5 -25.6 -27.8 -3.2 NV -2.7 -2.6 -2.6 -0.2

AZ -15.2 -16.7 -17.1 -2.2 OK -19.3 -25.8 -30.5 -2.9

CO -10.6 -20.6 -21.8 -2.1 SC -5.9 -8.0 -8.2 -0.7

HI -2.3 -2.3 -2.3 -0.4 SD -9.6 -19.8 -21.3 -2.3

KS -14.3 -21.9 -24.7 -2.7 TN -2.1 -2.3 -2.3 -0.2

ME -10.7 -20.4 -19.7 -3.1 WV -13.8 -17.2 -23.5 -1.9

MN -3.6 -2.5 -2.3 -0.3 WY -10.6 -21.8 -21.7 -2.2

MO -15.4 -21.3 -25.2 -2.3 Avg. -10.7 -16.3 -17.1 -2.0

Table D-5 15-Story Hotel Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK 2.7 -12.9 -7.7 -2.1 MS -25.0 -22.9 -22.8 -3.1

AL -18.6 -22.4 -24.3 -3.2 ND -0.4 -10.9 -12.9 -1.6

AR -9.1 -17.8 -21.0 -2.2 NV 6.0 6.8 6.5 0.6

AZ -9.2 -8.9 -8.8 -1.3 OK -7.9 -16.3 -22.5 -1.8

CO -3.4 -12.8 -13.9 -1.6 SC 7.4 5.0 4.7 0.6

HI 2.1 2.1 2.2 0.3 SD -3.0 -12.1 -13.4 -1.8

KS -7.0 -13.6 -15.9 -2.0 TN 5.8 6.7 6.9 0.6

ME -5.0 -13.6 -13.0 -2.4 WV -6.7 -9.7 -15.8 -1.4

MN 2.7 4.7 5.0 0.3 WY -4.0 -14.3 -14.2 -1.8

MO -7.3 -12.4 -15.8 -1.6 Avg. -3.2 -8.1 -8.8 -1.2
129

Table D-6 2-Story High School Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -2.4 -7.1 -5.3 -0.7 MS -16.8 -17.4 -17.4 -2.3

AL -12.3 -14.4 -15.6 -1.7 ND -4.9 -8.1 -8.9 -0.4

AR -6.4 -10.5 -12.1 -0.7 NV -3.4 -2.7 -3.0 -0.4

AZ -10.8 -11.4 -11.6 -1.5 OK -6.0 -9.8 -13.1 -0.3

CO -5.0 -8.8 -9.3 -1.1 SC -1.7 -2.0 -2.1 0.2

HI -1.0 -1.0 -1.0 -0.1 SD -5.0 -8.7 -9.4 -0.9

KS -7.1 -10.3 -11.6 -0.8 TN -3.1 -2.5 -2.3 -0.4

ME -4.9 -8.4 -8.2 -0.8 WV -6.7 -7.9 -10.7 -1.0

MN -3.4 -2.6 -2.4 -0.5 WY -5.2 -9.4 -9.3 -0.6

MO -7.1 -9.4 -11.2 -0.9 Avg. -5.8 -7.7 -8.2 -0.8

Table D-7 8-Story Office Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -6.0 -10.8 -9.5 1.1 MS -15.8 -14.5 -14.5 3.1

AL -15.3 -15.3 -15.3 1.1 ND -10.7 -12.5 -12.8 2.5

AR -13.8 -14.5 -14.7 -3.9 NV -3.2 -1.3 -1.8 -0.4

AZ -8.8 -7.8 -7.6 1.4 OK -16.0 -16.9 -17.4 2.4

CO -10.7 -10.6 -10.6 -2.6 SC -2.6 -2.1 -2.1 -0.7

HI -1.4 -1.4 -1.4 -0.3 SD -12.4 -12.9 -12.9 0.7

KS -16.0 -14.9 -14.6 3.0 TN -4.0 -1.8 -1.5 -0.8

ME -12.8 -13.4 -13.3 1.7 WV -13.3 -12.8 -11.8 -2.8

MN -5.6 -2.2 -1.9 -0.3 WY -13.7 -14.0 -14.0 2.2

MO -16.1 -14.8 -14.1 2.4 Avg. -9.8 -9.5 -9.3 0.5

Table D-8 16-Story Office Building Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK 4.0 -3.2 -1.0 -0.4 MS -14.1 -7.9 -7.6 -0.9

AL -9.1 -9.4 -9.6 -1.3 ND 2.2 -1.8 -2.4 -0.2

AR -3.5 -7.9 -9.4 -1.0 NV 5.8 7.0 6.7 0.8

AZ -1.9 -0.4 0.0 0.0 OK -2.9 -7.3 -10.4 -0.6

CO 0.3 -2.4 -2.7 -0.3 SC 5.6 3.7 3.5 0.5

HI 3.1 3.1 3.1 0.6 SD 1.2 -1.5 -1.8 -0.2

KS -1.0 -2.2 -2.7 -0.2 TN 6.4 6.8 6.8 0.8

ME -2.2 -4.2 -4.1 -0.7 WV -0.8 -1.5 -2.7 -0.2

MN 3.0 4.7 4.9 0.4 WY -0.4 -3.8 -3.7 -0.4

MO -0.7 -1.7 -2.3 -0.1 Avg. 0.5 -0.8 -0.9 -0.1
130

Table D-9 1-Story Retail Store Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -8.4 -13.9 -12.1 -0.7 MS -30.5 -27.3 -27.2 -1.3

AL -23.7 -23.6 -23.5 -1.2 ND -15.7 -18.0 -18.4 -0.3

AR -17.5 -18.7 -19.1 -2.6 NV -10.0 -6.4 -7.4 -1.2

AZ -19.9 -18.6 -18.3 -1.7 OK -19.1 -20.3 -21.1 1.4

CO -17.1 -17.3 -17.3 -2.9 SC -5.9 -4.9 -4.8 -0.1

HI -0.5 -0.5 -0.5 0.0 SD -16.1 -18.4 -18.7 -1.1

KS -19.4 -20.2 -20.5 0.2 TN -8.4 -5.3 -4.9 -0.4

ME -16.7 -18.5 -18.4 -0.9 WV -19.5 -19.4 -19.0 -2.6

MN -11.7 -6.9 -6.3 -0.3 WY -16.9 -18.9 -18.9 -0.9

MO -19.5 -19.9 -20.1 0.5 Avg. -15.2 -15.1 -15.0 -0.9

Table D-10 1-Story Restaurant Summary Table for ASHRAE 90.1-2007 and 

10-Year Study Period 

State

Percentage Change

State

Percentage Change

Energy Use Energy Cost Carbon LCC Energy Use Energy Cost Carbon LCC

AK -12.4 -17.0 -15.4 2.4 MS -24.8 -23.1 -23.0 3.6

AL -21.0 -22.1 -22.6 1.5 ND -20.6 -20.8 -20.9 2.9

AR -16.2 -19.6 -20.7 -3.1 NV -11.3 -6.7 -8.1 -1.7

AZ -16.1 -14.6 -14.2 0.8 OK -17.3 -21.0 -23.6 4.2

CO -18.6 -18.8 -18.8 -4.5 SC -2.8 -2.8 -2.8 -0.5

HI -2.6 -2.6 -2.6 -0.6 SD -19.9 -20.9 -21.0 0.3

KS -18.5 -20.1 -20.6 4.9 TN -4.4 -2.9 -2.6 -0.9

ME -22.8 -22.8 -22.8 1.4 WV -17.2 -17.8 -18.3 -3.5

MN -17.0 -10.1 -9.2 -2.2 WY -22.4 -22.9 -22.9 1.6

MO -16.3 -18.2 -19.3 4.6 Avg. -15.6 -15.5 -15.6 0.4
131

E Total Changes from Nationwide Adoption of the ASHRAE 90.1-2007

Design 

Table E-1 Total Reductions by State for Adoption of the ASHRAE 90.1-2007

Design, 10-Year 

State Code Average Annual New Floor Area

1000 m2(1000 ft2)

Energy Use 

(GWh)

Energy Costs 

($million)

Carbon 

(1000 tCO2e)

LCC 

($million)

AZ None 4758 (51 214) 946.3 62.2 561.7 30.8

NV 2004 3516 (37 844) 117.3 2.9 24.6 6.3

CO 2001 3292 (35 437) 543.0 35.0 541.4 53.9

TN 2004 3272 (35 219) 172.6 6.5 66.1 7.5

SC 2004 2718 (29 257) 92.2 6.5 60.7 2.9

MO None 2358 (25 383) 524.1 29.1 502.3 1.9

MN 2004 2329 (25 068) 282.7 6.0 70.8 7.3

AL None 2254 (24 266) 631.6 49.8 527.8 25.7

OK None 1590 (17 115) 300.5 29.1 502.3 -5.7

MS None 1251 (13 465) 470.6 28.1 281.2 12.3

AR 2001 1186 (12 762) 204.3 14.4 190.3 17.5

KS None 1077 (11 590) 229.5 13.9 208.4 -2.9

HI 2004 536 (5773) 12.1 2.1 10.8 2.0

ME None 497 (5349) 105.5 9.4 58.8 3.3

WV 2001 479 (5159) 96.4 5.0 78.8 7.2

SD None 303 (3262) 57.5 3.1 47.9 1.4

AK None 290 (3116) 14.0 4.3 22.0 1.4

WY None 230 (2477) 34.9 2.6 22.9 0.5

ND None 229 (2464) 45.7 2.4 37.7 0.0
132

Table E-2 Energy Use Reduction per Unit of Floor Area from Adoption of the 

ASHRAE 90.1-2007 Design, 10-Year 

State Code Average Annual New 

Floor Area

1000 m2(1000 ft2)

Energy Savings 

(GWh) kWh/m2

kWh/ft2

MS None 1251 (13 465) 470.6 376 35

AL None 2254 (24 266) 631.6 280 26

MO None 2358 (25 383) 524.1 222 21

KS None 1077 (11 590) 229.5 213 20

ME None 497 (5349) 105.5 212 20

WV 2001 479 (5159) 96.4 201 19

ND None 229 (2464) 45.7 200 19

AZ None 4758 (51 214) 946.3 199 18

SD None 303 (3262) 57.5 190 18

OK None 1590 (17 115) 300.5 189 18

AR 2001 1186 (12 762) 204.3 172 16

CO 2001 3292 (35 437) 543.0 165 15

WY None 230 (2477) 34.9 152 14

MN 2004 2329 (25 068) 282.7 121 11

TN 2004 3272 (35 219) 172.6 53 5

AK None 290 (3116) 14.0 48 4

SC 2004 2718 (29 257) 92.2 34 3

NV 2004 3516 (37 844) 117.3 33 3

HI 2004 536 (5773) 12.1 23 2
133

Table E-3 Life-Cycle Cost Reductions per Unit of New Floor Area from Adoption 

of the ASHRAE 90.1-2007 Design, 10-Year 

State Code Energy Use 

Savings 

(kWh/m2)

Electricity 

Rate 

($/kWh)

LCC 

Savings 

($million)

LCC 

Savings 

($/m2)

LCC 

Savings 

($/ft2)

CO 2001 165 0.08 53.9 16.37 1.52

WV 2001 201 0.07 7.2 15.03 1.40

AR 2001 172 0.08 17.5 14.76 1.37

AL None 280 0.10 25.7 11.40 1.06

MS None 376 0.10 12.3 9.83 0.91

ME None 212 0.13 3.3 6.64 0.62

AZ None 199 0.09 30.8 6.47 0.60

AK None 48 0.14 1.4 4.83 0.45

SD None 190 0.07 1.4 4.62 0.43

HI 2004 12 0.22 2.0 3.73 0.35

MN 2004 121 0.08 7.3 3.13 0.29

TN 2004 53 0.10 7.5 2.29 0.21

WY None 152 0.07 0.5 2.17 0.20

NV 2004 33 0.11 6.3 1.79 0.17

SC 2004 34 0.09 2.9 1.07 0.10

MO None 222 0.07 1.9 0.81 0.07

ND None 200 0.07 0.0 0.00 0.00

KS None 213 0.08 -2.9 -2.69 -0.25

OK None 189 0.07 -5.7 -3.58 -0.33

Table E-4 Energy Cost Reduction per kWh of Energy Use Reduction from 

Adoption of the ASHRAE 90.1-2007 Design, 10-Year 

State Code Weighted 

Offset

(%)

Electricity 

Rate* 

($/kWh)

Electricity 

Rate* 

($/kWh)

Energy Cost 

Reduction 

($/MWh)

AK None 66.2 % 0.14 0.03 307

HI 2004 0.0 % 0.22 0.09 174

OK None 24.4 % 0.07 0.03 97

ME None -14.7 % 0.13 0.04 89

AL None -3.5 % 0.10 0.04 79

WY None 17.2 % 0.07 0.02 74

SC 2004 5.0 % 0.09 0.03 70

AR 2001 24.1 % 0.08 0.03 70

AZ None -7.3 % 0.09 0.04 66

CO 2001 6.6 % 0.08 0.02 64

KS None -7.6 % 0.08 0.03 61

MS None -59.4 % 0.10 0.03 60

MO None -4.6 % 0.07 0.03 56

SD None -4.1 % 0.07 0.02 54

ND None -8.8 % 0.07 0.02 53

WV 2001 -10.1 % 0.07 0.04 52

TN 2004 -282.3 % 0.10 0.03 38

NV 2004 -230.6 % 0.11 0.03 25

MN 2004 -3113.8 % 0.08 0.02 21
134

Table E-5 Carbon Reduction per GWh of Energy Use Reduction from Adoption of 

the ASHRAE 90.1-2007 Design, 10-Year 

State Code Weighted 

Offset 

(%)

CO2e Emissions Rate 

for Electricity* 

($/kWh)

CO2e Emissions Rate 

for Natural Gas* 

($/kWh)

Carbon Emissions 

Reduction 

(tCO2e/GWh)

OK None 24.4 % 970 241 1672

AK None 66.2 % 663 241 1571

CO 2001 6.6 % 994 241 997

MO None -4.6 % 984 241 958

AR 2001 24.1 % 756 241 931

KS None -7.6 % 971 241 908

HI 2004 0.0 % 835 241 893

AL None -3.5 % 847 241 836

SD None -4.1 % 892 241 833

ND None -8.8 % 892 241 825

WV 2001 -10.1 % 875 241 817

SC 2004 5.0 % 647 241 658

WY None 17.2 % 661 241 656

MS None -59.4 % 759 241 598

AZ None -7.3 % 801 241 594

ME None -14.7 % 599 241 557

TN 2004 -282.3 % 819 241 383

MN 2004 -3113.8 % 892 241 250

NV 2004 -230.6 % 494 241 210