Summertime performance of an automated lighting and blinds control system

An innovative automated blind and lighting control system was developed to eliminate direct solar penetration and keep working plane illuminances within an optimal range, while making maximum use of daylight, and minimizing blind movement. Data collected from a controlled experiment indicate that the system eliminated direct solar glare and kept the working plane illuminance within the target range, while providing only 30 % more electric lighting than a theoretical system with no blinds and perfect knowledge of the working plane illuminance. The system needed to provide 60 % less electric lighting than a similar system with switchable rather than dimmable luminaires. Total blind movement varied from less than 1 min to over 6 min in one day depending on the weather, with an average of 190 s. Similar integrated systems have the potential to save a large fraction of the electricity used for lighting, while providing an amenable visual environment. List of symbols h Solar azimuth (in degrees) a Solar altitude (in degrees) Emin Minimum acceptable working plane illuminance Emax Maximum acceptable working plane illuminance ET Total illuminance on working plane ED Daylight illuminance on working plane EE Electric illuminance on working plane ECT Total illuminance at partially shielded ceiling sensor ECD Daylight illuminance at partially shielded ceiling sensor ECE Electric illuminance at partially shielded ceiling senso