Commercial and residential buildings consumed approximately 39% of the total energy used in the United States in 20021 with the remaining used in the industrial (33%) and transportation(28%) sectors. Approximately 4.6 million commercial buildings exist in the United States.2 Of these, 68% of the non-governmental buildings are owner-occupied, and the rest are leased or vacant.More than 90% of buildings owned by the U.S. federal government are owner-occupied.