Indoor lighting occupancy sensors detect activity within an area. They turn lights on automatically when someone enters a room. They reduce lighting energy use by turning lights off soon after the last occupant has left the room. The sensors must be located where they will detect occupants or activity in all parts of the room.
There are two types of occupancy sensors: Ultrasonic sensors detect sound, while infrared sensors detect heat and motion. In addition to controlling ambient lighting in a room, they are useful for task lighting applications, such as over kitchen counters. In such applications, task lights are turned on by the motion of a person washing dishes, for instance, and automatically turn off a few minutes after the person stops.
Both are readily available online and at retail stores.
Originally posted 2018-02-09 17:43:01.