A comparison of photosensor-controlled electronic dimming systems in a small office

Results from laboratory tests of commercially available photosensors and ba llasts are applied in a detailed computer model of a private office conside ring a variety of window and daylighting conditions. The laboratory measure ments include directional sensitivity, impact of calibration setting adjust ments, and the relative sensitivity of the photosensor to both daylight and electric light. For both a north- and a south-facing room, a "best-fit" calibration conditi on, which provided the best overall system performance, was determined for the sensor and related control hardware. The results of these best-case per formance settings are compared and discussed. In addition, the effect on system performance of changing the desk reflecta nce in the room from 0.20 to 0.60 was determined for each of the photosenso rs to characterize the sensitivity of these sensors to localized work-plane reflectance conditions.