A study has been initiated to provide follow-up analysis on the persistence of savings achieved from the retrocommissioning of ten buildings on a university campus. The buildings were originally commissioned in 1996, and the energy savings achieved over the next four years were tracked to evaluate their persistence levels. This study has now expanded the time frame after commissioning to an average of eight years by analyzing the energy consumption data for each building for the most recent year that valid data were available for the building. Preliminary results show high aggregate levels of savings persistence over the eight year average period for each building. The aggregate chilled water usage for the most recent data year for the ten buildings was virtually identical with the 1997 level, and only 56% of the baseline consumption. The aggregate hot water usage for the most recent data year for the ten buildings showed savings of 60.6% vs. savings of 66.4% for 1997, while the aggregate electricity savings were 22.9% vs. 11.5% for 1997. However, virtually all of the change in electricity use occurred in two buildings where it can not be regarded as a result of commissioning activities. The two buildings that required follow-up commissioning in 2001 (Kleberg and G.R. White) showed greater thermal savings after the follow-up than in 1997, suggesting that the 2001 effort was more thorough than that in 1997. If they are excluded from the analysis, the aggregate CHW savings of the other eight buildings decreased from 45.0% in 1997 to 36.3% in the most recent year while HW savings decreased from 54.4% to 40.5%. Even these savings show a high level of persistence over an average period of more than seven years. More analysis is needed to verify the quality of the data used in these comparisons, as well as to fill in some missing years where data are available. Follow up investigation is also needed to compare current building operating parameters with those in place just after commissioning and in the year 2000, to get a clearer picture of why changes in savings have occurred in each building
