Automated 'Eye-sight' Venetian blinds based on an embedded photometric device with real-time daylighting computing

摘要

Optimal shading control can improve occupants' visual comfort and increase energy savings on artificial lighting and cooling loads during warm seasons. A highly integrated automated shading system is presented in this paper. Designed to regulate daylighting according to the varying sky conditions in decentralized applications, it optimizes visual comfort for occupants and maximizes their view outwards. The shading control is based on real-time lighting simulation for a building interior based on sky (and landscape) luminance distribution monitoring. Its lighting simulation quality was validated in a daylighting test module showing a 10% root-mean-square error in both work-plane illuminance (WPI) and daylight glare probability (DGP). Conducted under various sky conditions during summer, autumn and winter, the shading control demonstrated its capability in regulating daylight provision, mitigating excessive solar heat gain, tempering discomfort glare, and maximizing outside view for occupants with minimal delay. The results showed that the WPI was maintained within the range of [500, 2000] lux in 96% of working time under clear skies and in between 79% and 88% of working time under partly cloudy skies. The expected mitigation of cooling loads due to excessive solar heat gain (SHG) was estimated to reach 47% during a warm climate, compared with no shading protection. The automated shading system was also demonstrated to successfully occlude glare due to secondary reflections on specular surfaces from surroundings.