Daylight sensing LED lighting system

Adaptation of artificial light based on the available amount of daylight is known to be effective for energy savings. To achieve such daylight control, the state-of-the-art lighting systems use external photodetectors. The photodetector measures the combined contribution of artificial light and daylight, and closed-loop control schemes are used to determine the dimming levels of luminaires to produce the right amount of artificial light. In this paper, we propose LED luminaires that can perform the dual function of illumination and daylight sensing, obviating the need of additional photodetectors. We present a daylight sensing luminaire prototype and consider two driving protocols for sensing and illumination. An open-loop control scheme is then considered for daylight control. The proposed system is shown to be more robust to reflectance changes in comparison with a photodetector-based closed-loop lighting control system.