Demand-Side Management and Energy Efficiency Revisited
The key finding of an influential paper that received the International Association for Energy Economists' Best Paper Award (2004) is that utilities have been overstating electricity savings and underestimating costs associated with energy efficiency demand side management (DSM) programs. This claim is based on point estimates of average DSM-related savings and costs implied by an econometric model of residential electricity demand. In this response we first argue that the choice of test statistics, by not weighting estimated savings and costs by utility electricity sales and DSM expenditures respectively, biases results in favor of rejecting the null hypothesis that utility-reported electricity savings reflect true values. We also note that utility estimates of average program savings and costs are rejected based on point estimates alone; no attempt is made to evaluate the uncertainty surrounding these estimates. We use the same data and econometric model to estimate the appropriate test statistics. We then construct nonparametric bootstrap confidence intervals. We fail to reject the average electricity savings and DSM program costs reported by utilities using both the weighted and unweighted test statistics. Our results suggest that the evidence for rejecting utility estimates of DSM savings and costs should be re-interpreted.