An Evaluation of Savings and Measure Persistence from Retrocommissioning of Large Commercial Buildings

Commercial building retrocommissioning activity has increased in recent years. LBNL recently conducted a study of 8 participants in Sacramento Municipal Utility District's (SMUD) retrocommissioning program. We evaluated the persistence of energy savings and measure implementation, in an effort to identify and understand factors that affect the longevity of retrocommissioning benefits.

The LBNL analysis looked at whole-building energy and the retrocommissioning measure implementation status, incorporating elements from previous work by Texas A&M University and Portland Energy Conservation Inc. When possible, adjustments due to newly discovered major end uses, occupancy patterns and 2001 energy crisis responses were included in the whole-building energy analysis. The measure implementation analysis categorized each recommended measure and tracked the measures to their current operational status. Results showed a 59% implementation rate of recommended measures.

The whole-building energy analysis showed an aggregate electricity savings of approximately 10.5% in the second post-retrocommissioning year, diminishing to approximately 8% in the fourth year. Results also showed the 2001 energy crisis played a significant role in the post-retrocommissioning energy use at the candidate sites. When natural gas consumption was included in the analysis, savings were reduced slightly, showing the importance in considering interactive effects between cooling and heating systems. The cost effectiveness of retrocommissioning was very attractive at the sites studied. However, funding for retrocommissioning activities is still very constrained.