Methodologies for Determining Persistence of Commissioning Benefits

Abstract

Studies on the persistence of commissioning benefits to date have used a variety of methods to evaluate this persistence. This paper proposes a consistent framework for describing and evaluating the persistence of commissioning benefits. It begins by splitting commissioning benefits into two broad categories: 1) benefits that inherently persist; and 2) benefits that may not persist. The study of persistence then considers only the benefits that may not persist. These benefits are critical, since the top five reasons cited for performing commissioning in both new buildings and existing buildings are benefits that may not persist. These benefits are then further divided into benefits that may be quantified and benefits that are generally difficult to quantify. This paper proposes that benefits that may be quantified should generally be evaluated for persistence using approaches that are already widely accepted and used for other purposes, with adaptations where needed. Specifically, it proposes that energy and water savings be evaluated using methods consistent with the International Performance Measurement and Verification Protocol (adapted with additional weather normalization), that comfort and indoor air quality improvements be evaluated using relevant standards, specifically ASHRAE Standard 55 and ASHRAE Standard 62, but goes further and proposes a methodology for economic quantification of these benefits as well. Finally, it is proposed that the persistence of measures whose benefit is difficult to quantify be evaluated simply by determining whether the measure is still in place or performing.