Conservation Program Evaluations

Abstract

The Seattle City Light Department evaluated its weatherization program for low-income homeowners to determine how much electricity was conserved, and whether the program was cost-effective. The study employed a control group offuture program participants in order to avoid the biased estimate that could result because participants are a voluntary, nonrandom group of utility customers. Surveys, energy audits, and electricity meter data confirmed the similarity of the experimental and control groups prior to home weatherization. Following the installation of conservation measures, the consumption of the experimental group declined by an average of 3400 Kwh per year, when compared with the control group. This experimental design is believed to have nullified the potential biases due to selection, testing, regression, history, and instrumentation. The bias due to mortality, defined in this study as customer turnover, was seen to be very minor. This design can be applied to evaluate programs that operate continuously, provided that the guidelines for the program do not change and that clearly defined measurements of program success are available.