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The Persistence of Retro-commissioning Savings in Ten University Buildings
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A study was performed to evaluate how well energy savings persisted over time in ten university buildings that underwent retro-commissioning in 1996. Total annualized savings for all buildings in 1997 were 45(±2)% for chilled water, 67(±2)% for hot water, and 12% for electricity. Combining consumption from the most recent data year for each building showed a total savings of 39(±1)% for chilled water, 64(±2)% for heating water, and 22% for electricity. Follow-up work performed in the buildings, lighting retrofits, and building metering changes were the major issues believed to have contributed to the high level of savings persistence in later years. When persistence trends were evaluated with adjustment for these factors, average savings were found to degrade over time, and exponential models were developed to describe this degradation. The study concludes that on average energy savings after retro-commissioning will degrade over time in a way that can be modeled exponentially. Savings for heating, cooling, and non-cooling electricity use in the buildings studied declined by an average of 8%, 6% and 4% per year, respectively following commissioning without further intervention.
DescriptionProceedings of the ICEBO Conference 2011, New York, NY
Toole, Cory (2011). The Persistence of Retro-commissioning Savings in Ten University Buildings. Energy Systems Laboratory. Available electronically from