Abstract: An environmental control system includes sensors in a room for sensing the environment and a sensor which may be a sound sensor, for detecting the presence or absence of a person in the room. With the aid of a digital computer, the presence or absence of a person in the room as determined by the sound sensor enables the computer to control the environment and also to actuate an alarm when a presence is sensed during an unauthorized time period. The system is applicable to one or more rooms.

Abstract: The environmental temperature in an area is controlled by the detection of the presence or absence of personnel in a room. A microphone detects sound in the room and actuates a control circuit to establish a set point for a temperature system which supplies heating and cooling to the room. The presence of people in the room is accompanied by sounds which are detected by the microphone to set the set point at an appropriate temperature to provide a comfortable environment. The absence of sound permits a new set point to be used to reduce the energy consumption of the heating or cooling system. A time delay circuit is optionally incorporated to eliminate undesirable cycling.