Do LEED-certified buildings save energy? Not really…

Newsham et al. have recently published a re-analysis of energy-consumption data for LEED-certified commercial buildings supplied by the New Buildings Institute (NBI) and US Green Building Council. They find that, on average, LEED buildings use 18–39% less energy per floor area than their conventional counterparts, consistent with and adding clarity to conclusions originally reached by NBI. These conclusions, however, hang on a particular definition of the mean energy intensity of a collection of buildings that is not related to the total energy used by those buildings. Furthermore, site energy considered by Newsham et al. and NBI, unlike source energy used for the EPA's building Energy Star rating, does not account for the energy consumed off-site in generating and delivering electric energy to the building, whose inclusion is crucial for understanding greenhouse gas emission associated with building operation. Here I demonstrate that both the site energy and source energy used by the set of 35 LEED office buildings and Newsham et al.’s matching CBECS office buildings are statistically equivalent. Hence Newsham et al. offer no evidence that LEED-certification has collectively lowered either site or source energy for office buildings.