@techreport {1724, title = {Photoelectric Control of Daylight-Following Lighting Systems}, year = {1989}, month = {02/1989}, abstract = {

The ability of daylight-following lighting systems to provide a minimum specified light level at the task surface is influenced by 1) the control algorithm used, 2) the spatial response of the ceiling-mounted control photosensor and 3) the location of the photosensor relative to task and window. Best performance was obtained with a closed-loop proportional control system controlled by a photosensor, with a large field of view but shielded from direct light from the window. A minimum specified illuminance level could be maintained at specific points on the task surface regardless of daylight condition or room geometry provided that the system gain was properly calibrated to account for the local luminous environment.

Open-loop proportional control also performed adequately but offered less precise control than closed-loop systems due to the necessity of using a photosensor that was not shielded from direct window light. Integral-reset systems that were tested performed poorly, but performance could be improved slightly by completely shielding the photocell from direct window light.

}, author = {Francis M. Rubinstein and Rudolph R. Verderber and Gregory J. Ward} } @article {12177, title = {Photo-Electric Control of Equi-Illumination Lighting Systems}, journal = {Energy and Buildings}, volume = {6}, year = {1983}, pages = {141-150}, abstract = {

A complete analysis of the cost-effectiveness of daylighting strategies should include the impact of daylighting on peak electrical demand as well as on energy consumption. We utilized an hour-by-hour building energy analysis program to study the thermal and daylighting impacts of fenestration on peak demand. Fenestration properties and lighting system characteristics were varied parametrically for office buildings in Madison WI and Lake Charles LA. Peak electrical demand was disaggregated by component and by zone, monthly patterns of peak demand were examined, and impacts of fenestration performance on chiller size were studied. The results suggest that for daylighted office buildings, the peak electrical demand results from a complex trade-off between cooling load due to fenestration parameters, lighting load reductions due to glazing and lighting system characteristics. Lowest peak demands generally occur with small to moderate size apertures. With daylighting, peak electrical demand is reduced by 10 to 20\% for the building configuration studied (37\% perimeter zone, 63\% core zone). This work indicates that solar gain through fenestration must be effectively controlled in order to realize the potential of daylighting to significantly reduce peak electrical demand.

}, author = {Francis M. Rubinstein} }