The simple toggle switch has long been the standard lighting control option in homes. Most everyone has seen them and they come in a huge variety of decorator finishes. Cover plates are also available in styles ranging from subtle and simple to the outrageous. The rooms were two entrances three-way switches can be more convenient. However, research shows, that even with convenient light switch locations, lights are often left on when rooms are unoccupied. These controls are inexpensive and easy to install, however, there are other options.
Dimmer controls provide variable lighting control. These switches provide some energy savings and were early attempt to reduce the wattage used by light bulb. Dimmers may operate by sliding or returning a knob. Dimmers were developed for incandescent lights, and were relatively inexpensive and easily available.
Timers are often used to give unoccupied houses, a lived in look, and reduce burglaries. However, they are not very effective in an occupied home, because they do not respond to people’s behaviour. Timers may be useful for turning off and on aquarium lights.
Occupancy sensors are becoming more common in homes. They detect activity within a certain area, and turn on the lights automatically when someone enters the room. They reduce indoor lighting energy use by turning the lights are. Soon after the last occupant has left the room. Therefore, the sensors must be located where they will detect the occupants or other activity in all parts of the room. There are two types of occupancy sensors, ultrasonic and infrared.
Ultrasonic sensors detect sound and infrared sensors detect heat and motion. In addition to controlling ambient lighting, they can be useful for controlling task lighting. For example, task lights can be turned on by the motion of the person washing dishes, and then automatically turn off shortly after the person stops. Because of their usefulness, I occupancy sensor technology will continue to improve.