Daylighting

Daylighting is an essential design strategy for zero energy buildings. Properly designed daylighting uses sunlight to offset electrical lighting loads, save energy, and reduce cooling loads.

Daylighting should provide controlled, quality lighting and deliver better lighting than electric lighting alone. Otherwise, occupants are encouraged to turn on the electric lights even when they are not needed. A good daylighting solution is one that will provide a minimum of 300 lux for at least 50% of the operating hours.

At the same time, direct sunlight into regularly occupied spaces should be limited. Good daylighting design seeks the right balance between enough daylight and too much sunlight, which can be a source of glare and excessive heat gain.

If designed correctly and followed up with appropriate occupant education, daylighting can reduce lighting energy, peak electrical demand, cooling energy, and maintenance costs.

 
Photo: NREL/DOE