The Persistence of Savings Obtained from Commissioning of Existing Buildings

Abstract

The objective of this study is to investigate the reasons why the performance of mechanical systems degrades over time after commissioning and to recommend intervals at which testing should be performed to maintain the integrity of the commissioning process. The initial phase of this study investigated the energy savings in ten buildings commissioned between 1996 and 1997. The results of this study show that hot water, chilled water and electric savings have all degraded. Aggregate annual cost savings for the ten buildings decreased by 17% from 1998 to 2000 from $1,192,884 to $985,626. The investigation has found that the decreased savings are due to numerous changes in control settings since the commissioning and to significant control malfunctions in two buildings.