Skylight

A skylight (sometimes called a rooflight) is a light-permitting structure or window, usually made of transparent or translucent glass,[1] that forms all or part of the roof space of a building for daylighting and ventilation purposes.

A fixed skylight consists of a structural perimeter frame supporting glazing infill (the light-transmitting portion, which is made primarily of glass or plastic).

[4] Sloped glazing differs from other "skylights" in that one assembly contains multiple infill panels in a framing system, usually designed for a specific project and installed in sections on site.

Increased daylighting can result in less electrical lighting use and smaller sized window glazing (sidelighting), saving energy, lowering costs, and reducing environmental impacts.

[7] Many recent advances in both glass and plastic infill systems have greatly benefited all skylight types.

Assemblies with three panes can sometimes be cost-justified in the coldest climate zones, but they lose some light by adding the third layer of glass.

Lack of accepted standards for measuring light transmittance is a disadvantage for comparing and choosing skylights with plastic glazing.

[8] NFRC: rating for visible transmittance U-factor: expresses the heat loss performance of any building assembly.

In selection of skylights, a balance is sought between low U-factor and optimal SHGC values, while preserving enough daylight supply to minimize artificial light use.

[9] Other studies show that daylight positively affects physiological and psychological well-being, which can increase productivity in many contexts, such as sales in retail spaces.

The majority of commercial warehouses and 'big box stores' built in recent years have used skylights extensively for energy/costs savings.