As air-conditioning demand has increased significantlyduring the last decade, efficient energy use has become moreimportant due to large electric power demands and limitedreserves of fossil fuel. Electrical energy use fluctuates significantlyduring a 24-hour day due to variable demand fromindustrial, commercial, and residential activities. In hot andcold climates, the dominant part of the load fluctuation iscaused by cooling and heating demands, respectively. If electricloads could be shifted from peak hours to off-peak hours,not only would building operation costs decrease but the needto run peaker plants, which typically use more fossil fuels thannon-peaker plants, would also decrease. Thus, shifting electricityconsumption from peak to off-peak hours promoteseconomic and environmental savings. This paper uses simulationand experimental work to examine 12 precooling strategiesin three residential buildings in the Phoenix, Arizona,climate. The selected buildings are considered to represent themajority of residential buildings in the area. Results of thisproject show that precooling can save up to 46% of peak energydemand in a home constructed with concrete or cementitiousblock and up to 35% in wood frame homes. Homeowners cansave up to U.S. $244/year in block construction and up toU.S. $119/year in wood frame homes.