Lighting control system based on digital camera for energy saving in shop windows

Shop window lighting usually represents a meaningful quantity in the lighting consumption of a shop because the large amount of installed power and its high number of running hours. Dimming of lighting can improve its energy efficiency, however, conventional systems, as photocell detectors, are difficult to be used. Besides, the usual control objective of daylight harvesting cannot be applied in this context because here the main objective is to maintain the attractiveness on shop window.In this paper, a control system for shop window lighting is proposed. In this system, a digital camera as a luminance meter has been used. Furthermore, the main objective of the controller is to keep constant the contrast of the shop window interior with respect to its surroundings.The proposed control has been tested in a shop window prototype where real working conditions have been simulated.

► A low cost digital camera has been used as relative luminance meter.
► A control system that uses contrast as an objective is proposed.
► A control system that estimates exterior light contribution.
► The proposed system has been tested in a shop window prototype.