conditioning (HVAC) loads, and plug loads. Data were tabulated every 15 minutes and the data were used to calibrate the computer simulation models. Among the study findings were the following:
Evaluating the Energy Performance of the First Generation of LEED-Certified Commercial Buildings
R. Diamond, M. Optiz, T. Hicks, B. Von Neida, and S. Herrera. Lawrence Berkeley National Laboratory: Berkeley, Calif. 2006.
This study by Diamond et al. presented an early analysis of the actual energy performance of 21 LEED-certified buildings that were certified between December 2001 and August 2005. The study does not indicate what certification levels had been achieved by individual buildings.
The study compared the modeled energy use for LEED-NC-certified buildings (data taken from the submissions required for LEED certification) against actual utility bills for the first year of operation (utility billing data were collected from 2003 to 2005). Modeled energy data were collected for both the as-designed building and the base-case building. The authors note the study is “only a preliminary guide to how LEED buildings in general are performing as a group” due to a range of issues. The issues included the sample size, the wide variation in building type (libraries, offices, multifamily, mixed use, laboratories) and building size (from 6,100 square feet to 412,000 square feet); 14 buildings were owned by the federal government, certified as LEED-NC, and located across the country; 7 buildings were commercial and concentrated mostly in the Pacific Northwest.
For the 18 buildings for which the authors had both simulated whole building design and actual purchased energy, the actual consumption was 28 percent lower than the base-case. However, there was significant variation among individual buildings, with some being more energy efficient than predicted, and some being less efficient. The actual energy use in the federal buildings was lower than the modeled