Technology Reviews: Daylighting Optical Systems

Conventional daylighting design components (i.e. fenestration systems) can normally provide adequate daylight in the perimeter of buildings, i.e. within 15 feet of windows or skylights. To provide daylight in a larger fraction of the building area requires one of two approaches. One option is to increase the fraction of the floor area that is adjacent to fenestration using architectural design strategies to alter floor plans from rectangular to reentrant forms, use of atria, stepping back upper stories of the building, etc. The second option is to use daylighting optical systems to deliver light to building locations beyond the perimeter zone. In this section, we present several technical approaches for introducing daylight and sunlight deeper within buildings. We consider situations where light transmission is desired over longer distances (15 - 100) and where it may be desirable to penetrate either horizontally or vertically through the core of a building. These includes daylighting techniques based on the use of light shelves, wide window sills, special reflectors, louvers, baffles, reflective blinds, and other ways to direct light deep into the buildings plan. These methods are intended to avoid the glare and the strong modulation (intense light near the window, rapidly falling off with increasing depth) of direct-beam daylighting.