Modelling and hybrid control of building lighting systems

The development of an accurate control system for shading devices, essentially motorised Venetian blinds, relies on the rational use of daylight in buildings. This study proposes a control strategy for building lighting components, both daylighting and artificial lighting, to automatically adjust the light level in an office building as required and to block direct sunlight from entering the office, when necessary. The proposed control strategy is based on a hybrid statecharts model mainly consisting of a supervisory control system that chooses appropriate control actions for a current sky condition depending on the sky ratio and clearness index. These control actions are implemented to automatically adjust the blind height and slat angle, and turn on the artificial lighting only when needed. Real experiments in a test-cell demonstrate the effectiveness and flexibility of the proposed control strategy.