This issue of Specifier Reports provides guidance on selecting, installing, and adjusting photosensors, including manufacturer-supplied data and brand-name performance results. Although some photosensors simply switch lights on and off, this report focuses on photosensors used with dimming electronic ballasts to adjust the light output of fluorescent lighting systems over a continuous range. These photosensors are most commonly used in daylight applications to dim electric lighting when total illuminance exceeds a preset level. Photosensors have seen limited application for three reasons: actual energy savings are difficult to predict, occupants sometimes complaint about photosensors, and anecdotal reports of difficulties in properly installing and adjusting photosensors. NLPIP intends this report to promote better understanding of this technology. |