Re-Assessing Green Building Performance: A Post Occupancy Evaluation of 22 GSA Buildings

Abstract

2nd report on the performance of GSA's sustainably designed buildings. The purpose of this study was to provide an overview of measured whole building performance as it compares to GSA and industry baselines. The PNNL research team found the data analysis illuminated strengths and weaknesses of individual buildings as well as the portfolio of buildings. This section includes summary data, observations that cross multiple performance metrics, discussion of lessons learned from this research, and opportunities for future research. The summary of annual data for each of the performance metrics is provided in Table 25. The data represent 1 year of measurements and are not associated with any specific design features or strategies. Where available, multiple years of data were examined and there were minimal significant differences between the years. Individually focused post occupancy evaluation (POEs) would allow for more detailed analysis of the buildings. Examining building performance over multiple years could potentially offer a useful diagnostic tool for identifying building operations that are in need of operational changes. Investigating what the connection is between the building performance and the design intent would offer potential design guidance and possible insight into building operation strategies. The 'aggregate operating cost' metric used in this study represents the costs that were available for developing a comparative industry baseline for office buildings. The costs include water utilities, energy utilities, general maintenance, grounds maintenance, waste and recycling, and janitorial costs. Three of the buildings that cost more than the baseline in Figure 45 have higher maintenance costs than the baseline, and one has higher energy costs. Given the volume of data collected and analyzed for this study, the inevitable request is for a simple answer with respect to sustainably designed building performance. As previously stated, compiling the individual building values into single metrics is not statistically valid given the small number of buildings, but it has been done to provide a cursory view of this portfolio of sustainably designed buildings. For all metrics except recycling cost per rentable square foot and CBE survey response rate, the averaged building performance was better than the baseline for the GSA buildings in this study.