Natural light is an important element in visual comfort and it sometimes influences the quality of vision. The effect of daylight on the human biological cycles and possible physiological alterations in the absence of natural light during the day are well-known.
When visual comfort is not completely satisfied, the application of daylight transportation systems in buildings is relevant. Research on and observation of human behaviour and the biological effects of light have shown the vital role of artificial or natural light, in maintaining the physiological and psychological balance in human organisms. When visual comfort is not completely satisfied the constant use of artificial light cannot give a temporal reference, so a careful design of the building as well as the use of a specific daylight component (to control, capture and distribute daylight) that contributes to maintaining the natural light changes in intensity and colour temperature is necessary.