Implementation of fuzzy logic in daylighting control

The sustainable development concept has revived the interest for daylighting as any day lit area has very promising energy-saving opportunities; according to some specialists, the potential energy savings can exceed 40%. However, daylight is a dynamic source of lighting, i.e. the illuminance from the sky is not constant, and the variations in daylight can be quite large depending on season, location or latitude, and cloudiness. As a result, electric lighting control systems will be needed from time to time to adapt the lighting systems to changing lighting conditions. Classic control systems, based on continuous dimming present some difficulties to adjust their performances to the rapid changes in daylight and to occupants' preferences. Taking into account these aspects, fuzzy control could be a better solution. The paper analyzes the possibility to implement this new technique in daylighting control and presents the structure of a fuzzy controller proposed by authors; its operation rules and the influence on the imposed value of the illuminance level are also studied.