Abstract
A set of candela distribution curves(CDCs) were generated for a fiber optic dish daylighting system by Photopia under clear sky conditions at different solar altitudes. The candela distribution curves were then exported to Radiance for photometric analysis of a windowless lecture room. Observations were made on the Radiance rendered illuminance images, which provided photo realistic scenes varying with solar altitudes. If no tracking error were assumed, the daylight collection efficiency of the system remained at a constant value of 68.4% during its operation. Higher the solar altitude angle, greater in photometric quantities were observed, which are represented by candela(cd) and total lumens(lm). In all cases considered, however, the angle of light distribution remained fixed reflecting the solar tracking feature of the system. The illuminance uniformity on the workplane lingered around 0.12, which is quite low. This is quite a contrast to its average value of 0.68 of the $2.7m^2$ area directly below the terminal device (diffuser) of the system. The maximum illuminance of 1,340lux was obtained at a solar altitude of 80 degrees.
