In many instances, we may be able to custom design a system for your clients which will aim to maximize the use of sunlight to illuminate interior building space. Photo sensors are used to measure natural light levels and then the artificial lighting can be adjusted accordingly and automatically.
Several studies have recorded the energy savings due to daylight harvesting. Energy savings for electric lighting in the range of 20-60% are common. Savings are very dependent on the type of space the light harvesting control system is deployed in, and its usage. Clearly, savings can only accrue in spaces with substantial daylight where electric lighting would have been otherwise used. Therefore daylight harvesting works best in spaces with access to conventional or clerestory windows, skylights, light tube groups, glass block walls, and other passive daylighting sources from sunlight; and where electric lighting would otherwise be left on for long periods. Such spaces have included offices, atria, interior public multistory plazas and shopping mall courts, and schools.
It is too simplistic to try to increase energy savings by increasing the size of windows. Daylight over-illumination may cause glare for occupants, causing them to deploy blinds or other window shading devices, and compromising the daylight harvesting system. Even partially-deployed venetian blinds can cut energy savings in half.