Lighting System Performance in an Innovative Daylighted Structure: An Instrumented Study

This paper presents conclusions from a one-year instrumented study of an innovative daylighted commercial building in the San Francisco Bay area. The building, a five-story structure housing 3,000 employees, has a series of architectural features specifically developed to admit daylight into interior office zones. These are complimented by a continuously dimmable fluorescent lighting system that supplements available daylight under the control of open-loop ceiling-mounted photosensors. Monitored data indicate that the architectural daylighting features of the building are performing admirably and contribute significant daylight to most areas of the buildings open plan offices. Field tests have determined that, under manual control, the electric light dimming hardware is capable of dimming to 27% of full power consumption. Operational savings, however, are limited by inappropriate performance of the control system in many of the building's lighting circuits.