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Incorporating real-world data into measure lifetime estimates: How long does energy efficient equipment really last on-site?

Rose Woods and Lisa A. Skumatz, Skumatz Economic Research Associates, Inc. (SERA), USA


measure lifetimes, EULs, measure retention, savings lifetimes, energy efficient measures, estimated program savings, technical degradation


In work for a large west coast agency, the authors conducted a detailed assessment of more than 100 measure retention / lifetime studies to identify the real-world lifetimes for numerous energy saving measures used in: 1) Residential, 2) Low income, 3) Commercial / industrial, 4) agricultural, and 5) military buildings. Estimated useful lifetimes (measure lifetimes), in conjunction with energy savings estimates, are the key elements in computing energy savings for a program or intervention. Many of these EULs had not been updated for more than a decade.

The study provides quantitative information on: 1) updated measure lifetimes for scores of commonly-installed program measures; 2) information on measures for which reliable lifetime information is not currently available; 3) information on technical degradation studies, and 4) best practices for measure lifetime analyses.

For each study, the authors conducted an exhaustive review of program measures, sampling methodologies and approach; field work; data validation; and analysis steps to determine whether reliable lifetime information could be gleaned from the study. The paper summarizes these results and provides information on updated / recommended EUL estimates for energy efficiency equipment. The implications related to gaps in available EUL information – especially as it relates to key equipment – and reliable estimates of EUL values for planning for future programs are presented.


Download this paper as pdf: 4.319_Woods.pdf