An environment control system permitting the occupant of a room or space in a multi-room building sharing a common air supply conduit with other rooms to control the environment in his or her room selectively and/or automatically. The system =includes a small wireless portable remote control unit readily accessible to the occupant for selecting predetermined conditions. These conditions are transmitted to a remote receiver which provides signals to a main control unit coupled to external environmental control units such as motors which operate damper valves in the room, air conditioning units supplying air to the common conduit heaters within the room and the like. Both the remote control unit and the main control unit include a programmed microcontroller. The portable control unit may be used to select the desired environmental conditions within the room while the lights are on and transmits this information to the main control unit which acts to energize and deenergize the external control units. When the occupant leaves the room and turns the light off, infrared transmissions from the portable control unit cease after a short period of time and the main control unit thereafter takes over and controls the temperature in the room in accordance with programmed conditions.