Computational analysis on the enhancement of daylight penetration into dimly lit spaces: Light tube vs. fiber optic dish concentrator

Capturing daylight into an unevenly lit lecture room with north-facing windows has been analyzed with the help of Photopia and Radiance. Two different daylighting systems, a light tube and a fiber-optic solar dish concentrator, are considered as means to lead light rays into an interior space with insufficient illumination from daylight. Photopia is used to photometrically model the daylighting systems as light travels through highly reflective light guiding elements of these systems. The candela power distribution curves (CDCs) generated by Photopia are imported by Radiance to produce photometric data and images of different locations in the lecture room. These results clearly reveal the functional benefits of each system when harvesting daylight for indoor illumination. For solar altitudes of less than 50 degrees, more daylight can be harvested by the solar tracking dish concentrator system. Also, its minimum-to-average (illuminance) uniformity ratio on the work plane remains between 0.55 and 0.72, varying quite less than that of the light tube, ranging from 0.46 to 0.88. (C) 2012 Published by Elsevier Ltd.