Combined electric light and daylight systems ecodesign

Natural daylight in interior has two main characteristics: - is extremely pleasant to humans, - is a free energy contribution. Daylight can allow to reduce the electric lighting power with consequent savings on the energy bill. The application of sensors, control systems, and information technologies can reduce significantly the need for human work. By controlling the lighting in such a way that the lighting level is always accurately matched to the actual need allows to save on the energy costs and to improve the human comfort and efficiency. The paper suggests adaptive criteria to organize a combined electric light and daylight systems ecodesign and a criterion to evaluate the daylight availability.