A program with 13 participants provided reimbursement for improvements to decrease energy use largely in commercial and not-for-profit buildings but also in two government buildings. Electricity and natural gas savings were determined by modeling the energy use by accounting for changes in weather for the 12 months previous to the improvements, and then predicting energy use for the 12 months immediately after the improvements using the same model.
The threshold for verifiable energy savings resulting from building improvements was a maximum uncertainty of 50% at the 68% confidence level. Improvements involving original furnace or air conditioner replacement resulted in significant and verifiable reductions in energy use. Energy savings due to lighting improvements were verified for only one of seven buildings in which lighting was upgraded. Verifiable results were obtained in buildings with constant usage patterns, hours of operation, and equipment. Significant changes not related to weather, and improvements resulting in less than 10% savings of the total energy measured at the meter led to non-verifiable results.
Other benefits of the program not related to energy cost savings included increasing illumination while maintaining the same electricity use, and improving comfort and noise reduction with additional insulation. The program was very successful in leveraging significant private investment for building improvements. In addition, the program inspired business owners to make further improvements voluntarily after the program ended and also increased interest in similar future programs.
Mathias, James A., Harrell, Justin M. and Tetzlaff, Marian. "Review and Analysis of an Energy Efficiency Incentive Program for Commercial Buildings." (Jan 2008).