Daylighting is the planned use of natural daylight in buildings. It is usually supplemented by electric lighting.

The presence of natural daylight emanates a sense of well-being. It creates a feeling of warmth and cleanliness. Although in tropical climate, light from the sun which casts strong shadow is associated with a sense of intense radiation and excessive heat, light from the rest of the sky is gentler and is welcome.

Daylight is variable. Changing sky conditions during the course of a day causes the intensity of daylight to vary. Also, the colors and hues of daylight near sunrise and sunset times change slowly with time. The variation creates a sense of expectation and excitement. Use of daylight reduces the sense of monotony in a visual scene.

Daylighting can be energy efficient. The efficacy of daylight itself exceeds those of artificial sources with reasonable color rendition.

However, in air-conditioned buildings, windows are closed to reduce infiltration and exfiltration (or air leakage). The glazed windows allow viewing the exterior scene from the confined space in the building interior. The associated greenhouse effect of trapped solar radiation which increases load to the air-conditioning system has led the construction industry to the use of glazings with coatings or films of low visible (and thermal) transmittivity. Even with a large glazed window, or in some cases the glazings fill the wall of a façade, the resultant penetrated daylight is insufficient for illuminating the interior. Electric lighting is fully employed. In such cases daylight merely contributes to exacerbate the thermal environment and to increase the energy required for air-conditioning. But proper use of daylight for daylighting in building interior can simultaneously reduce energy for lighting and air-conditioning.