The energy and environmental consequences of conditioning buildings are immense, andbecoming more so around the world. In the United States, buildings consume 38% of thenation’s energy consumption, a larger amount than the industrial, transportation, or agriculturalsectors. In the global context, the U.S. currently consumes 25% of the world’s energy,meaning that 10% of the world’s energy is being used in U.S. buildings! About 80% of thisbuilding use is for heating, cooling, ventilating, and lighting. The huge construction boom inChina, India, and the developing countries is rapidly increasing these countries’ need forenergy. If their new buildings were to have the same efficiency as the U.S. building stock, theglobal impacts will be severe. At this point there is little evidence that they will be appreciablydifferent.The engineering and architecture professions need to invest maximum creative effort intoimproving the efficiency by which our indoor climates are produced. There are two maincomponents to the energy use problem in buildings: the buildings themselves (theirarchitectural form and their environmental conditioning systems) and the people who occupyand operate the buildings.