Daylighting
Daylighting is an important element of sustainable design. The incorporation of daylight in the design of a building is justified for a number of reasons.
Aesthetics
Besides energy savings, daylighting provides a host of non-energetic benefits. Daylight research over the last decade has shown strong statistical correlations with daylighting and increases in sales, learning and productivity. In the health field, the discovery that certain characteristics of light transmission by the human eye regulate melatonin production in the pineal gland was only made a decade ago. Research and application of the far-reaching effects of this circadian response are still being discovered, from its affect on our sleep/wake cycle to the body's ability to fight cancer.
Color Quality
Daylight, due to its spectral composition, provides excellent color rendering.
Energy Issues
Building energy consumption can be reduced if daylight is used in appropriate quantities to illuminate interior spaces and reduce the reliance on electric lighting.
Benefits to Occupants
Daylight can provide potential benefits to building occupants in terms of health, performance, or general well being.
The design of a daylight delivery system, which consists of building elements that are designed to bring daylight into a space, is a complex task.
To achieve a successful and integrated design, daylight must generally be incorporated into a building design from the initial schematic phases of the design. This section provides only a general introduction to the practice of daylighting.
Daylight Delivery Systems
Skylights are common daylight delivery elements that are incorporated into the roof of a building. As such, they can only generally be applied on the top floor of a building or in a single story building, although an atrium can permit daylight from skylights to be introduced to multiple floors of a building.
Windows are, perhaps, the most common daylight delivery device used in buildings today. In many cases, windows provide considerable daylight, but no attempt is made to take advantage of this daylight through the control of electric lighting. A window offers a distinct advantage because it provides the occupants with a view of the exterior, a desirable attribute for those who must remain inside for an entire work day.
With no obstructions (such as office partitions) and a standard window with Venetian blinds, usable daylight can only penetrate into a space approximately one to two times the height of the top of the window above the work plane.
Typically, the best locations for windows are on the south and north sides of a building. On east and west exposures, low angle sunlight at sunrise and sunset can create extreme glare conditions, as well as high solar gain and should be avoided, if possible.
A light shelf is a daylight delivery element that is used with a window to reflect daylight to the ceiling and decrease daylight levels adjacent to a window. It is more applicable to building facades and sites that will experience significant amounts of direct sunlight.
