Measured Savings vs. Engineering Estimates: An Analysis of Differences Between Program Assumptions, Engineering Surveys and Field-Monitored Data

Panel: Panel 2: Programme Evaluation

Author:
Harry Misuriello, Energy Conservation and DSM Consultant

Abstract

This paper presents findings from in-situ impact evaluations of commercial sector DSM savings undt?r both direct ƒ rebate and custom rebate approaches. The focus of the paper is a quantitative analysis of differences between DSM program planning assumptions, engineermg surveys and field-monitored data. This information provides real-world feedback to DSM implementation staff, Impact parameters of interest include gross first-year savings and load shape impacts. The major method discussed in this paper is short-term before-and-after field monitoring of affected end-uses coupled with an analysis of DSM program rebate forms. This paper uses results obtained from short-term energy measurements performed at sites monitored as part of the Commercial, Industrial and Agricultural (CIA) Retrofit Incentives Evaluation Program sponsofed by the Pacific Gas & Electric Company, a major U.S. utility in California. A total of 90 sites were field-monitored for this project. The DSM measures include those typically found in these sectors; i.e., lighting, motors and HVAC modifications.

The paper addresses the following topics: determination of DSM savings through short-term measurement techniques; comparison of field-measured savings to prescribed savings for direct rebates and to custom rebate engineering estimates; and an engineering assessment of differences in these estimates. It is these custom rebate sites that are most interesting. Even with detaled on-site engineering surveys supporting the rebate savings estimate, differences in key parameters such as connected lighting load and hours of operation were uncovered. The paper explains these differences and recommends procedures to improve.DSM estimates.