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Project: T131700 #7060

Effective useful life (EUL) identifies how long energy savings from energy efficient measures persist and is an important variable in calculating rates of return on energy efficiency investments. The majority of EUL data used in North America comes from only a few key sources and is often based on a limited set of market studies or best judgments. However, some organizations have identified these data issues and are taking action to improve the quality and rigour of EUL development. In this study, we examine the EUL assumptions and methodologies used by organizations across North America to calculate energy savings from hardwired and non-hardwired energy efficiency.

The objectives of this study are two-fold: (1) to improve upon the current EUL data reference sources available, by compiling the best possible EUL data to address well known data gaps and highlight data that has been validated, and (2) to identify the different practices and data sources used in the development and application of EUL data in North America. In this study we review the literature and conduct an industry survey to develop a user-friendly, regionally-relevant and transparent database of suggested EUL values for select measures in the residential, commercial, industrial and agricultural sectors.


Effective useful life, Measure life, Energy efficiency, Energy conservation, Energy savings