How Many Kilowatts are in a Negawatt? Verifying "Ex Post" Estimates of Utility Conservation Impacts at the Regional Level

The current movement toward utility restructuring raises questions about the future of utility conservation programs, which have long suffered from all-informed and conflicting perceptions about their ability to affect customer loads. Controversy has arisen because of the inherent difficulty in measuring conservation impacts and because utilities have had clear economic incentives to overestimate impacts. This study uses econometric techniques to examine the aggregate commercial and industrial conservation impacts reported ex post by 39 utilities in the Northeast U.S. and California through 1993. The study finds that 99. 4% of the reported conservation impacts are statistically observable in system level sales after accounting for economic and weather effects. The results indicate that utility-run conservation programs have, indeed, been effective in reducing customer loads. The study finds no evidence the utilities have systematically overstated conservation effects.