Daylighting is the complete process of designing buildings to utilize natural light to its fullest.
Because daylighting practice involves fundamental architectural considerations, it is difficult to undertake once the building has been designed, or, in the case of an interior design project or tenant improvement, almost impossible to carry out.
Daylighting is an excellent light source for almost all interior spaces. It is best for offices, schools, and workspaces requiring a lot of light and for public spaces such as malls, airports, and institutions. Windows, skylights, and other forms of fenestration are used to bring daylight into the interiors of buildings. Daylight is highly desirable as a light source because people respond positively to it.
The amount of available daylight varies according to time of day, time of year, weather, pollution levels, and so on. The maximum amount of daylight is about 10,000 foot-candles on a sunny summer day. For energy efficiency in buildings, however, only about 5% of the daylight, or a peak of about 500 footcandles, should be allowed into a building; more will generate so much heat that energy will be wasted in air conditioning.
One of the most common ways to introduce daylight is through skylights and other means of top lighting. Top lighting behaves as direct electric lighting does—by radiating light downward. Principles commonly used for designing electric lighting systems can also be used for top lighting, which is the easiest form of daylighting and is relatively unaffected by site orientation and adjacent buildings.
Side lighting employs vertical fenestration (usually windows) to introduce natural light. Unlike top lighting, side lighting tends to introduce light that can be too bright relative to the room surfaces, sometimes causing glare. However, the desirable view provided by windows usually makes glare an acceptable side effect.