Behavioral Perspectives on Home Energy Audits: - Earth Advantage

395 Pages·2012·10.81 MB·English

by  Rebecca Smith

Behavioral Perspectives on

Home Energy Audits:

The Role of Auditors, Labels, Reports, and
Audit Tools on Homeowner Decision-Making

Aaron Ingle, Mithra Moezzi, Loren Lutzenhiser, and Zac Hathaway
Portland State University

Susan Lutzenhiser, Joe Van Clock, and Jane Peters

Research Into Action

Rebecca Smith and David Heslam
Earth Advantage Institute
Rick Diamond
Lawrence Berkeley National Laboratory

July 2012
DISCLAIMER
This document was prepared as an account of work sponsored by the United States Government. While
this document is believed to contain correct information, neither the United States Government nor any
agency thereof, nor The Regents of the University of California, nor any of their employees, makes any
warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process disclosed, or represents that its use would
not infringe privately owned rights. Reference herein to any specific commercial product, process, or
service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or
imply its endorsement, recommendation, or favoring by the United States Government or any agency
thereof, or The Regents of the University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States Government or any agency thereof
or The Regents of the University of California.
This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy,
Building Technologies Program, of the U.S. Department of Energy under Contract No. DE-AC02-
05CH11231.

Acknowledgements
The authors would like to thank Joan Glickman, Christa McDermott, and David Lee at the U.S.
Department of Energy; Oradoña Landgrebe and Andrew Gibb at Seattle City Light; Sara Stiltner at the
City of Seattle; Ammen Jordan at Home Performance Collaborative; Kristen Nice and Dave Henson at
Puget Sound Energy; and Amber Johnson, Debi Elliot, and Tara Horn of Portland State University. We
would also like to thank Tom Sanquist at Pacific Northwest National Laboratory and Alan Sanstad and
Evan Mills at the Lawrence Berkeley National Laboratory for providing thoughtful review of a draft of
this report.

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Contents
List of Tables ................................................................................................................................................. 4
List of Figures ................................................................................................................................................ 5
Acronyms and Abbreviations ....................................................................................................................... 8
Executive Summary ...................................................................................................................................... 9
1. Introduction and Background ............................................................................................................. 21
2. Approach ............................................................................................................................................. 31
3. Industry Actors’ Opinions and Perceptions—Auditors & Realtors ..................................................... 47
4. Homeowner Decision-Making Related to Energy Upgrades, Audit Reports, and Labels ................... 71
5. Post-Retrofit Assessment and Retrofit Quality Verification ............................................................. 118
6. Home Energy Audit and Assessment Modeling Tool Comparison ................................................... 125
7. Conclusions ....................................................................................................................................... 148
References ................................................................................................................................................ 159

Appendix A: EPS Scorecard....................................................................................................................... 163
Appendix B: EPS Energy Analysis Report .................................................................................................. 165
Appendix C: Sample Home Energy Score Report ..................................................................................... 179
Appendix D: Auditor Interview Guide ...................................................................................................... 182
Appendix E: Auditor Interviews Results – Presentation to Team, 3/2/11 ............................................... 186
Appendix F: Real Estate Professionals Interview Guide ........................................................................... 191
Appendix G: Real Estate Professionals Interviews Presentation 8/16/11 ............................................... 195
Appendix H: Homeowner Pre-Audit Interview Guide .............................................................................. 200
Appendix I: Homeowner Pre-Audit Interview Closed-Ended Responses ................................................. 207
Appendix J: Homeowner Post-Audit Interview Guide .............................................................................. 211
Appendix K: Homeowner Post-Audit Interview Closed-Ended Responses .............................................. 222
Appendix L: Post-Audit Survey Questions and Responses ....................................................................... 228
Appendix M: Retrofit Survey Questions and Responses .......................................................................... 277
Appendix N: Details of Modeling Data Processing and Preparation ........................................................ 323
Appendix O: EPS Auditor, Home Energy Scoring Tool, and HESPro Feature Comparison ....................... 330
Appendix P: Comparison of Asset-Based Energy Use Estimates .............................................................. 334
Appendix Q: Comparison of Model Estimates to Utility-Reported Energy Usage ................................... 345
Appendix R: Assessment of Impact of Missing Home Energy Scoring Tool Inputs .................................. 368
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Appendix S: Comparison of Recommendations—EPS Auditor and Home Energy Scoring Tool .............. 371
Appendix T: Model Assumptions of “Standard” Operation Compared to Reported Behaviors .............. 383

List of Tables
Table 1: Overview of research data streams .............................................................................................. 11
Table 2: Overview of research data streams .............................................................................................. 31
Table 3: House and household sample ....................................................................................................... 35
Table 4: Characteristics of audited households as compared to SCL Customer Survey............................. 36
Table 5: Demographic characteristics of survey respondents compared to the community overall ........ 38
Table 6: Number of completed homeowner interviews and surveys by category .................................... 41
Table 7: Mapping of house and homeowner data streams to completed analyses .................................. 44
Table 8: Typical homeowner-initiated post-audit call-back topics ............................................................. 56
Table 9: Factors considered and their impact on recommendations ......................................................... 58
Table 10: Auditor use of “General Notes” field in audit report .................................................................. 59
Table 11: Summary of number of completed homeowner interviews and surveys .................................. 71
Table 12: Reasons cited by Pre-Audit Interviewees for seeking an audit (multiple responses allowed) ... 74
Table 13: What part of the audit process was particularly helpful in convincing household members .... 78
Table 14: Responses on the relative importance of Energy Score versus Carbon Score ........................... 81
Table 15: Reasons given for having undertaken audit (Post-Audit Survey; n=134) ................................... 86
Table 16: After your energy audit, have you discussed your Energy Score ............................................... 88
Table 17: Completed or intended upgrades cited more often after the audit .......................................... 89
Table 18: Completed or intended upgrades cited less often after the audit ............................................. 90
Table 19: How much Retrofit Survey respondents reported learning ....................................................... 92
Table 20: Percentage of audited households receiving “standardized” recommendations ...................... 95
Table 21: Considerations in priority of upgrades (Post-Audit Interviews; n=12) ....................................... 96
Table 22: Number of recommendations that survey respondents reported having completed ............... 99
Table 23: Energy upgrade recommendations received and reported completed ................................... 100
Table 24: Reasons homeowners gave for choosing the retrofits they completed ................................... 102
Table 25: Reasons homeowners gave for delaying planned retrofits (Retrofit Survey; n=95) ................ 102
Table 26: Reasons given for deciding against particular recommendations (Retrofit Survey; n=61) ...... 103
Table 27: Who performed the upgrades that were completed? (Retrofit Survey; n=82) ........................ 103
Table 28: Rating of likelihood of incentive affecting upgrade decision (Pre-Audit Interview; n=33) ...... 104
Table 29: Post-Audit Interview responses to whether it would be “worth” taking out a loan ................ 105
Table 30: Total estimated expenditures for all energy upgrades performed for the households ........... 107
Table 31: Homeowner perceptions of savings from recommended upgrades they undertook .............. 108
Table 32: Reported changes in energy use practices after the audit or after upgrades .......................... 112
Table 33: Summary of upgrade quality assessment, by upgrade type (n=50 houses) ............................. 120
Table 34: Similarities and differences between EPS Auditor, Home Energy Scoring Tool, and HESPro .. 128
Table 35: Data sets utilized for the model comparison ............................................................................ 130
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Table 36: Modeling tools and emulators used in the analyses ................................................................ 131
Table 37: Six model comparison analyses completed .............................................................................. 132
Table 38: All Home Energy Scoring Tool recommendations for 31 homes .............................................. 135
Table 39: All EPS Auditor tool recommendations for 31 homes .............................................................. 135
Table 40: Thermostat setbacks reported in the energy use behavior survey .......................................... 140
Table 41: Percentage of homes where EPS asset model estimated usage was substantially lower........ 142
Table 42: Percentage of homes where Home Energy Scoring Tool asset model estimated .................... 142
Table 43: Percentage of homes where HESPro house+weather+behavior model estimated usage ....... 144
Table 44: Findings from the SCL Home Energy Audit study compared to the literature ......................... 149
Table 45: Missing or ambiguous data informing Home Energy Scoring Tool inputs ................................ 325
Table 46: Similarities and Differences between EPS, Home Energy Scoring Tool, and HESPro ............... 330
Table 47: Summary of all EPS and Home Energy Scoring Tool Comparison Runs .................................... 338
Table 48: Total Site Energy (kWheq/yr)—Comparison of Asset, Asset+Weather .................................... 348
Table 49: Total Source Energy (MBTU/yr)—Comparison of Asset, Asset+Weather ................................ 352
Table 50: Electricity Usage (kWhr/yr)—Comparison of Asset, Asset+Weather ....................................... 355
Table 51: Natural Gas Usage (therms/yr)—Comparison of Asset, Asset+Weather ................................. 359
Table 52: Percentage of homes where EPS asset model estimated usage was substantially lower........ 362
Table 53: Percentage of homes where Home Energy Scoring Tool asset model estimated usage .......... 362
Table 54: Percentage of homes where HES-ProHESPro “house+weather+behavior” model .................. 363
Table 55: 15 Houses with Post-Retrofit Assessment Additional Information vs. Home Energy Score .... 369
Table 56: All Home Energy Scoring Tool recommendations for 31 homes .............................................. 373
Table 57: All EPS report “standardized” recommendations for 31 homes .............................................. 373
Table 58: Summary of air sealing recommendations made in EPS Auditor ............................................. 375
Table 59: Details of the 10 air sealing recommendations that coincided ................................................ 375
Table 60: Summary of attic insulation recommendations ....................................................................... 377
Table 61: Details of the 11 attic insulation recommendations that coincided ........................................ 377
Table 62: Summary of floor or basement insulation recommendations ................................................. 378
Table 63: Details of the 7 floor or basement insulation recommendations that coincided .................... 378
Table 64: Summary of duct insulation recommendations ....................................................................... 380
Table 65: Details of the 5 duct insulation recommendations that coincided .......................................... 380
Table 66: Thermostat Setting Assumptions Used in Modeling Tools ....................................................... 384
Table 67: Self-reported thermostat settings from survey respondents ................................................... 384
Table 68: Number of respondents reporting using a particular supplemental heating source ............... 386
Table 69: Large appliance use model assumptions .................................................................................. 389

List of Figures
Figure 1: Overview of the home energy audit process and associated actors included in the research ... 12
Figure 2: Overview of the Seattle City Light home energy audit process .................................................. 29
Figure 3: House and household data streams collected in this research ................................................... 35
Figure 4: Home energy audit process and data collection activities .......................................................... 40
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Figure 5: Blower door test photo................................................................................................................ 51
Figure 6: Example of EPS savings estimates ............................................................................................... 55
Figure 7: Example of costs reported for recommended energy upgrades from the EPS Report ............... 56
Figure 8: Home labeling and real estate market demand for energy efficient houses .............................. 61
Figure 9: Four current home label options ................................................................................................. 63
Figure 10: Ways labeling differentiates new and existing homes .............................................................. 64
Figure 11: Potential drawbacks to labeling new and existing homes ........................................................ 65
Figure 12: Sample EPS Scorecard ................................................................................................................ 80
Figure 13: Changes in infiltration between values recorded .................................................................... 122
Figure 14: Major sets of activities for model comparison ........................................................................ 129
Figure 15: Estimated total site energy use for Home Energy Scoring Tool compared to EPS .................. 133
Figure 16: Summary of comparison of upgrade recommendations ......................................................... 136
Figure 17: Self-reported and model estimated occupancy vs number of bedrooms in home ................ 139
Figure 18: Histogram of fractional change in model estimated total site energy use of a home ............ 141
Figure 19: Major data collection, processing, and preparation activities for model comparison ........... 323
Figure 20: Percent difference in estimated total source energy use. ...................................................... 327
Figure 21: Percent difference in estimated total source energy use ....................................................... 328
Figure 22: Scatter Plots Comparing EPS and Home Energy Scoring Tool Total Energy Use Estimates .... 339
Figure 23: Distribution of the Percent Difference Between EPS and Home Energy Scoring Tool ............ 340
Figure 24: Scatter Plots Comparing EPS and Home Energy Scoring Tool Total Electricity and Nat Gas ... 341
Figure 25: Distribution of Percent Difference Between EPS and Home Energy Scoring Tool Electricity . 341
Figure 26: Scatter Plots Comparing EPS and Home Energy Scoring Tool Space Heating ......................... 342
Figure 27: Distribution of the Percent Difference Between EPS and Home Energy Scoring Tool ............ 343
Figure 28: Scatter Plots of Model Estimated Total Site Energy vs Utility Reported Usage ...................... 349
Figure 29: Distribution of the Percent Difference Between Model Estimated Total Site Energy ............ 350
Figure 30: Scatter Plots of Model Estimated Total Source Energy vs. Utility Reported Usage ................ 353
Figure 31: Distribution of the Percent Difference Between Model Estimated Total Source Energy ....... 354
Figure 32: Scatter Plots of Model Estimated Electricity Usage vs. Utility Reported Usage ...................... 356
Figure 33: Distribution of the Percent Difference Between Model Estimated Electricity Usage ............. 357
Figure 34: Scatter Plots of Model Estimated Natural Gas Usage vs. Utility Reported Usage ................... 360
Figure 35: Distribution of the Percent Difference Between Model Estimated Natural Gas Usage .......... 361
Figure 36: HESPro+Weather+Behavior model estimated electricity use versus. ..................................... 365
Figure 37: Residuals plotted as a function of the regression predicted value for HESPro ....................... 366
Figure 38: Asset model estimated heating use (site kWheq/yr): EPS vs Home Energy Scoring Tool ....... 372
Figure 39: Asset model estimated air sealing savings: EPS vs Home Energy Scoring Tool ....................... 376
Figure 40: Asset model estimated attic insulation savings: EPS vs Home Energy Scoring Tool ............... 377
Figure 41: Asset model estimated floor or basement insulation savings ................................................. 379
Figure 42: Asset model estimated duct insulation savings: EPS vs Home Energy Scoring Tool ............... 380
Figure 43: Self-reported supplemental heating use ................................................................................. 386
Figure 44: Self-reported and model estimated occupancy versus number of bedrooms in home. ........ 387
Figure 45: Response to question about whether someone is home during the day ............................... 388
Figure 46: Dishwasher use as reported by energy use behavior survey respondents ............................. 390
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Figure 47: Energy use behavior response on typical washing machine cycle setting .............................. 390
Figure 48: Washing machine use reported by energy use behavior survey respondents ....................... 391
Figure 49: Clothes dryer use reported by energy use behavior survey respondents .............................. 391
Figure 50: Measured hot water temperatures from EPS home energy audits ........................................ 393
Figure 51: Histogram of fractional change in model estimated total site energy use of a home ............ 394

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Acronyms and Abbreviations

ACHn Natural air changes per hour
BPI Building Performance Institute, Inc.
CFL Compact fluorescent lamp
CFM Cubic feet per minute
CFM50 Airflow needed to create a change in building pressure of 50 Pascals
DOE U.S. Department of Energy
EPS Energy Performance Score
HERS Home Energy Rating Systems
HESPro Home Energy Saver Pro
kWh Kilowatt hour
kWheq Kilowatt hour equivalent
LBNL Lawrence Berkeley National Laboratory
LEED Leadership in Energy and Environmental Design rating system
MPG Miles per gallon
NAR National Association of Realtors
NREL National Renewable Energy Laboratory
REPs Real estate professionals
SCL Seattle City Light
S.T.A.R. Earth Advantage Institute’s Sustainability Training for Real Estate Professionals
educational course

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Executive Summary
Overview
During 2010 and 2011, thousands of news articles promoted the potential benefits of home energy
audits and of subsequent energy efficiency improvements, signaling a resurgence of interest in
motivating homeowners to assess and upgrade their homes. An increasing number of home energy
audit programs were already underway in the United States, and auditors, utilities, and others learn
from these experiences, and continue to try to design more effective audits, pitches, and programs, as
they have for more than thirty years (e.g., Hirst et al. 1981; Van de Grift and Schauer 2010)—since the
advent of home energy audits in the 1970s.
These home energy audits have generally been designed to overcome what the industry commonly
considers “barriers” to increasing home energy efficiency, in particular the perception that homeowners
do not have enough information about what to do to increase the energy efficiency of their homes or to
solve performance problems, nor about the prospective advantages of these actions. Home energy
audits are furthermore sometimes used to generate an energy score to inform potential home buyers
about energy efficiency and thereby influence the overall housing stock, to qualify homes for energy
efficiency financing, mortgages, loans, or incentives, and to diagnose home energy performance
problems.
Despite success stories (e.g., Van de Grift and Schauer 2010), the results of home energy audit programs
overall have often been considered disappointing: relatively few households undertake audits, and
when they do, upgrade recommendations are often not acted upon (Frondel and Vance 2011; Fuller et
al. 2010; Palmer et al. 2011). And though there is clearly remaining technical potential, little has been
proven about the overall energy savings that result from audits and resulting upgrades, nor the extent to
which actual social potential can reach technical potential. Rather than continue to ask why
homeowners do not act as theory suggests they should, this research turns the lens more toward
homeowners’ views and experiences. A clearer, more open understanding of these views and
experiences may help expectations for home energy audits better align with what is likely to be
achieved.
Our study focused on the perspective of homeowner decision-making in response to home energy
audits, combined with attention to the quality of the recommendations that homeowners receive, as
well as the perspectives of some key industry actors on auditing and home energy labels. Unlike a
program evaluation, the research was not designed to answer detailed questions about program
effectiveness in terms of costs, savings, or process, nor was it designed to provide direct answers to
questions of how to get people to do more audits or more retrofits. Rather it “steps back” toward a
better understanding of more basic questions about what audits provide and what homeowners seem
to want, for the case of one particular program that we expect has parallels to many others.
In this report, we present the results of a study for the U.S. Department of Energy, applied to an existing
home energy audit program and pilot offered by Seattle City Light, the electric utility for the City of
Seattle. Portland State University, Research Into Action, and Earth Advantage Institute worked together
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with Seattle City Light and the Lawrence Berkeley National Laboratory to complete the research project.
From mid-2010 to late 2011, approximately 1,350 home energy audits were completed in Seattle as part
of Seattle City Light’s program. These audits, and the homeowners who received them, are the subject
of our report.
The research reported here was designed to advance the field’s knowledge on what homeowners want
and get from home energy audits. It did so by simultaneously studying multiple dimensions of these
audits, including: physical characteristics of the houses audited, the energy use estimates and upgrade
recommendations these audits offered to homeowners, actual energy use data, self-reported retrofit
activity and energy use behaviors, physical assessment of the quality of the retrofits undertaken,
viewpoints of both auditors and realtors on various key program elements, and—centrally in tying these
streams together—homeowner motivations and reactions to the audits, what they consequently
changed, and what they thought about the results. These data were used to address gaps in knowledge
about home energy efficiency upgrades and audits, including:
 Homeowner decision-making processes in planning and undertaking energy retrofits, reactions to
home energy performance scores, and satisfaction with the audits performed;
 Differences and similarities between home energy assessment and retrofit recommendation tools;
 Importance of household energy behaviors relative to house- and equipment-based assessments of
home energy performance and upgrade recommendations; and
 Industry views on the current and potential future use, and usefulness, of home energy performance
ratings in general.

While we collected as much as 18 months utility consumption data for these households, the post-
retrofit period was typically only 6 months, which was not sufficient to statistically test the degree of
energy savings associated with audits and upgrades.
Seattle City Light’s Home Energy Audit Program
In 2010, Seattle City Light began a program offering Seattle City Light customers owning single-family
homes a $400 home energy audit for a discounted rate of $95, with an objective of reaching 5,000
households. These home energy audits used BPI-certified auditors, diagnostic testing, asset-based
energy modeling, and an auditor-customizable report featuring an asset rating of the house’s energy
and carbon use, upgrade recommendations, and the energy performance details of the house. Earth
Advantage Institute’s EPS Auditor modeling and reporting software tool was used for these audits.
The Seattle City Light program provided an assessment of the whole house, including attic, walls,
windows, foundations, water heating, ducts, and heating and cooling system(s), as well as
measurements of air leakage, combustion safety checks, and, when feasible, infrared thermal imaging.
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