Use controls to minimize lighting energy use
Lights use less energy when dimmed, and the least energy when turned off. You can use controls to adjust light levels based on ambient light, or occupancy. This graph shows one example of how much energy can be saved by using controls. The dark green represents the savings.
Image: With permission from Fundamentals of Lighting 2015 PowerPoint Slides published by the Illuminating Engineering Society
Photocells are commonly used for outdoor lighting control. They detect light levels and automatically turn lights off when it is light out. Photocells can also be used to dim interior lights as more daylight enters the building.
Occupancy sensors can be used to turn lights on when people are in a space, and/or turn them off when people leave the space. There are a variety of types of sensors, that are each suited to different situations. Infrared uses line of sight, so it works well in open spaces. Ultrasonic can be used in spaces with partitions. Microphonic listens for people sounds, so can be used where there is little movement.
Timers can be used to automatically have spaces lit only when needed. For example, if a parking lot is vacated by 10pm, the timer can shut the lights off at that time.
The various types of controls can be combined, as in the image above.
Most controls have sensitivity adjustments and adjustable “on-time” settings to prevent excessive switching. Whatever type of controls you install, be sure that they are compatible with the type of lighting you are controlling.