Natural lighting in architecture is essential as it provides visual comfort, reduces the amount of conventional energy used and, at the same time, diminishes thermal gains indoors caused by artificial lighting. According to Millet (1996), For all light sources, the luminous effect depends upon four factors: the source (its intensity, its directional characteristics, its color); the geometry (its relationship between the source and the receiver or receiving surface); the surfaces that receive and modify light, becoming secondary light sources in themselves by reflecting, redirecting, and coloring light.