Evaluating the energy performance of the first generation of LEED-certified commercial buildings
Over three hundred buildings have been certified under the Leadership in Energy and Environmental Design (LEED) rating system for sustainable commercial buildings as of January 2006. This paper explores the modeled and actual energy performance of a sample of 21 of these buildings that certified under LEED between December 2001 and August 2005, including how extensively the design teams pursued LEED energy-efficiency credits, the modeled design and baseline energy performance, and the actual energy use during the first few years of operation. We collected utility billing data from 2003-2005 and compared the billed energy consumption with the modeled energy use. We also calculated Energy Star ratings for the buildings and compared them to peer groups where possible. The mean savings modeled for the sample was 27% compared to their modeled baseline values. For the group of 18 buildings for which we have both modeled and billed energy use, the mean value for actual consumption was 1% lower than modeled energy use, with a wide variation around the mean. The mean Energy Star score was 71 out of a total of 100 points, higher than the average score of 50 but slightly below the Energy Star award threshold of 75 points. The paper discusses the limitations inherent to this type of analysis, such as the small sample size of disparate buildings, the uncertainties in actual floor area, and the discrepancies between metered sections of the buildings. Despite these limitations, the value of the work is that it presents an early view of the actual energy performance for a set of 21 LEED-certified buildings.