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

Results from laboratory tests of commercially available photosensors and ballasts are applied in a detailed computer model of a private office considering a variety of window and daylighting conditions. The laboratory measurements include directional sensitivity, impact of calibration setting adjustments, 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 condition, which provided the best overall system performance, was determined for the sensor and related control hardware. The results of these best-case performance settings are compared and discussed. In addition, the effect on system performance of changing the desk reflectance in the room from 0.20 to 0.60 was determined for each of the photosensors to characterize the sensitivity of these sensors to localized work-plane reflectance conditions.