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CALMAC July 18, 2007 Meeting Attribution and Net to Gross Examples for Discussion Clark Bernier, RLW Analytics, Inc. Energy Star® Homes Evaluation “Difference of Differences” •Usage/savings results from all Participant and a sample of NonParticipant Title 24 models •ESH 02/03 and 04/45 evaluations verified a sample of Participant models •Baseline study verified Non-Participant models •Matched Non-Participants to Participants by CEC CZ and/or RMST •Calculated average compliance margins for participants and nonparticipants in each CZ (relative to “standard” Package D) •Difference between the average compliance margins was the net savings margin •(energy saved / baseline energy usage) •Multiplied by adjusted tracking baseline usage to get net savings 2 Energy Star® Homes Evaluation “Difference of Differences” - Issues •Need a well-matched Participant and Non-Participant group •Separate baseline study made this difficult •Different sampling frames •RMST w/clustering v. Population •Distribution over CEC CZs not comparable •RMST zones good for characteristics overview, bad for predicting energy usage/savings •Didn’t meter non-participants: assumed metering adjustments affected Parts and Non-Parts equally 3 Savings by Design Evaluation: Self-Reported Model Adjustments Surveyed the builders of all sites in the sample For each site, determined influence of the program measure-by-measure Dichotomous for yes/no measures Continuous for continuous measures Adjusted each measure accordingly in each site’s DOE2 model Re-ran simulation with net-adjusted measures—savings compared to baseline were net savings 4 Savings by Design Evaluation: Self-Reported Issues Significant “gaming” of system Learned to ask “how” program affected savings Some buildings are built from common plans Learned to ask about the program’s impacts on measures in the plans/prototypes instead of in the buildings Potentially more accurate, but more difficult to compute net-to-gross ratio Without running many different combinations of measures by source, it is difficult to attribute savings beyond a simple net/gross split 5 Utility-Specific Savings from Statewide Programs/Evaluations Utility Sample UtilityUtility Sample Samples Utility Utility Utility Ratios Ratios Ratios Utility Utility Utility Tracking Tracking Tracking Statewide Program/ Evaluation Statewide Sample Utility Sample UtilityUtility Sample Savings Statewide Ratio Utility Utility Utility Tracking Tracking Tracking 6