Comparison of Metering and Verification Methodologies of Compressed Air Systems for Utility-Based Energy-Efficiency Programs: A Case-Study

Measurement and verification (M&V) is an important component of energy-efficiency projects and programs because the results show if the intended savings of a project are being realized. The accuracy of these results impacts the investment strategies of energy end users and regional transmission organizations, like Pennsylvania Jersey Maryland (PJM), who can view and purchase efficiency credits as a resource. It also impacts the incentive strategies of utility efficiency programs. Often the standards for custom M&V projects place tight controls on the accuracy of the metering equipment used, but have relatively loose controls on the methodologies required to analyze the metered data. This paper provides a background on PJM’s M&V standards and shows through case studies how the potential error associated with analysis approach can greatly outweigh the errors associated with selected metering equipment. Compressed air systems are a common mechanical system chosen by industry for energy efficiency retrofits. Due to the many variables present in multiple-compressor systems, they often do not qualify for a prescriptive rebate programs. In the case studies provided, analysis is conducted for pre- and post-efficiency project scenarios with and without normalizing for air demand. In addition, the case studies demonstrate how different methodologies for normalizing can also have a large impact on the calculated energy savings.