| Keywords |
Lightshelf ; Photosensor-based lighting control ; Daylight factor ; Dimming ; Sky condition ; Correlation ; Lighting energy savings |
| Abstract |
This study examines the influence of lightshelf configurations on photosensor-based lighting control in a narrow-shaped office space. Computer simulations were conducted for three options for window configurations including lightshelf under a variety of daylight conditions. Results indicate that daylight factors under lightshelves conditions were lower than that of the conditions without lightshelf, since the lightshelf functions as an overhang that blocked incoming daylight to workplanes. The amount of dimmed light for the case with and without lightshelf was approximately equal. The photosensor positioned 2 m away from window provided excessive dimming under all sky conditions and failed to provide a target illuminance. The photosensors at 5 m and 8 m away from the window were effective under clear and partly cloudy sky conditions. The control system generated excessive dimming under overcast sky and undershot the target illuminance. When lightshelves were used, the correlation between workplane illuminance and photosensor illuminance by daylight was stronger compared to the case of no lightshelf. At least, 67.8% of lighting energy savings on average was achieved by the lighting control system. |