Transcript Major Topic
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
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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
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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
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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
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Utility-Specific Savings from
Statewide Programs/Evaluations
Utility
Sample
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Samples
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Ratios
Ratios
Ratios
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Tracking
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Tracking
Statewide
Program/
Evaluation
Statewide
Sample
Utility
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Savings
Statewide
Ratio
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Tracking
Tracking
Tracking
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