The potential of simplified concepts for daylight harvesting

Abstract

Daylighting systems offer tremendous potential for reducing the energy consumption of electric lighting, but their usage has been inhibited by high costs and imperfect performance of current technologies. This paper presents predictions of energy savings for two proposed daylighting technologies, a daylight-sensing switch and an automatic blinds system, which employ simple, inexpensive components and designs. Assumptions of solar irradiance, blind position, blind operation behaviour, and light switching behaviour were combined with illuminance data and daylight factors to develop an algorithm for calculating the potential energy usages of six different systems in commercial private offices and open plan offices. Results show that the combined usage of the proposed technologies perform with an average annual energy saving of 24% compared with manual switching and blinds operation in Albany, New York. Compared with a photosensor-operated dimming system, the proposed technologies combined show better performance during summer months. Comparisons were also made for the systems in six US climatic regions.