Daylight Harvesting

Daylight harvesting is the use of natural lighting as the main source of general illumination in a space. Several studies over the last fifty years have confirmed the value of daylight in design. Also called daylighting control or automatic daylight dimming or switching, daylight harvesting uses a ceiling, wall or fixture-mounted light sensor to calculate the amount of lighting at the work surface in a space or at the daylight aperture, then signals a switch or dimming ballast to regulate light output from the electric lighting system to keep the desired level of illumination. Here are some of the mistakes many people make when they set up daylight harvesting systems:
 

Daylight harvesting systems should only be set up by a technical expert who will make modifications specific to space and location. Rearranging furniture and making other changes to the lit space, small as they may be, can alter its reflective properties and call for costly expert adjustments. Many of the systems in use today use tools that allow the system to fine-tune itself continuously and automatically, adjusting to any changes in the room and reducing the need for expert commissioning.

Daylight must be properly incorporated with the electric lighting system for its energy-saving potential to be realized. The primary strategy for energy conservation is to use lighting controls that switch or dim the lights in response to available daylight. Switching is often recommended for spaces where people don’t have to work, since the changes in light levels can be quite abrupt and irritating. Continuous dimming is the usual strategy for office spaces. Daylight harvesting promotes energy efficiency, and it also prevents the adverse health effects of over-illumination by artificial light.