Description:

Daylight harvesting sensors require the installation of photocells to sense the space lighting level and control the overhead lighting in the perimeter zones to maintain a constant light level in the space. This measure also includes replacing the overhead lighting with dimmable ballasts, since dimmable ballasts are necessary to realize energy savings.

Special Considerations

• The lighting next to the exterior windows needs to be on a separate circuit from the other lighting, so that these lights can be controlled separate from the interior zone lights.
• The design of a daylight harvesting system should account for sensor location, sensor orientation, and number of sensors. During installation, the light sensitivity settings need to be adjusted so that the desired lighting level is maintained in the space. Also, the system should be periodically tested for proper functionality.

Estimates for this measure come from the Department of Energy's Advanced Energy Retrofit Guide.