Dimmers
Motion Sensors
Occupancy Sensors
Photosensors
Timers

Most everyone knows that you can save energy by turning off lights when they're not needed. But sometimes we forget or don't notice that we've left lights on. Lighting controls can be used to automatically turn lights on and off as needed, preventing energy waste.

The most common types of lighting controls include the following: dimmers, motion sensors, occupancy sensors, photosensors, and timers.

Dimmers
Dimmer controls provide variable indoor lighting for incandescent and fluorescent lamps. When you dim these lamps, it reduces their wattage and output, which helps save energy.

Off-the-shelf dimmers for incandescent fixtures are inexpensive and provide some energy savings when lights are used at a reduced level. Dimmers also increase the service life of incandescent lamps significantly. However, dimming incandescent lamps reduces their lumen output more than their wattage. This makes incandescent lamps less efficient as they are dimmed.

Dimming fluorescents requires special dimming ballasts and lamp holders, but does not reduce their efficiency. Fluorescent dimmers are dedicated fixtures and bulbs that provide even greater energy savings than a regular fluorescent lamp.

Motion Sensors
Motion sensors automatically turn outdoor lights on when they are needed (when motion is detected) and turn them off a short while later. They are very useful for outdoor security and utility lighting provided by incandescent lamps.

Because utility lights and some security lights are needed only when it is dark and people are present, the best way to control might be a combination of motion sensor and photosensor.

Incandescent flood lights with a photosensor and motion sensor may actually use less energy than pole-mounted high-intensity discharge (HID) or low-pressure sodium security lights controlled by a photosensor. Even though HID and low-pressure sodium lights are more efficient than incandescents, they are turned on for a much longer period of time than incandescents using these dual controls.

When turned on, HID and low-pressure sodium lamps can also take up to ten minutes to produce light. Therefore, they don't work well with just a motion sensor.

Lighting controls can save energy and reduce peak demand in offices and other facilities. Controls save money while providing user convenience and an improved lighting environment. There are several different kinds of controls. The choice of control should be based on lighting usage patterns and the type of space.

Occupancy Sensors Occupancy sensors—indoor lighting controls—detect activity within a certain area. They provide convenience by turning 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. Occupancy sensors must be located where they will detect occupants or occupant activity in all parts of the room. There are two types of occupancy sensors: ultrasonic and infrared. 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.

Photosensors
You can use photosensors to prevent outdoor lights from operating during daylight hours. This can help save energy because you don't have to remember to turn off your outdoor lights.

Photosensors sense ambient light conditions, making them useful for all types of outdoor lighting. They offer little utility in controlling lights inside the home because lighting needs vary with occupant activity rather than ambient lighting levels.

Timers
Timers can be used to turn on and off outdoor and indoor lights at specific times.

Simple timers are not often used alone for outdoor lighting because the timer may have to be reset often with the seasonal variation in the length of night. However, they can be used effectively in combinations with other controls. For example, the best combination for aesthetic (decorative) lighting may be a photosensor that turns lights on in the evening and a timer that turns the lights off at a certain hour of the night (e.g., 11 P.M.).

For indoor lighting, timers are sometimes used to give unoccupied houses a lived in look. However, they are an ineffective control for an occupied home because they do not respond to changes in occupant behavior, like occupancy sensors.

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Source: Energy Efficiency and Renewable Energy (EERE), Department of Energy