A cell phone location-based system is described that determines the occupancy of a home and controls home energy consumption such that energy is saved when the home is unoccupied. Occupancy is determined according to cell phone locations, occupant behavior patterns, or burglar alarm status. When an occupant is determined to be returning to their unoccupied home, the heating or cooling apparatus is activated to return the temperature in the home to a comfortable level by the time the occupant arrives.