| Keywords |
Anidolic Light-duct System ; RADIANCE ; Photon Map ; LDI(Light Duct Index) |
| Abstract |
Various types of daylighting systems have been developed to save electric energy for interior illumination in modern buildings by effectively admitting natural light into the space. Among the daylight systems, anidolic lightduct systems are developed to admit direct sunlight at the light collector located on the side walls, normally southfacing wall, transport to the admitted sunlight through light duct with high-reflectance interior surfaces, and illuminate indoor spaces by light diffuser. The efficiency of anidolic light duct system is affected by various design variables including the aperture size of the light collector, geometric configuration and reflectance of the light guiding duct and the diffusing character of the light diffuser. In this study, the efficiency of illumination in terms of illuminance levels were tested by different geometric configuration of the light duct. The geometric configuration of light duct was expressed by LDI(Light Duct Index) which is the same as the Well Index of atrium spaces. The illuminance level were calculated for equinoxes and summer and winter solstices by the RADIANCE program with Photon map algorithm. Then, the illuminance classes defined by KS A 3011 were identified for the different LDIs. The result showed that for the LDI values from 2.17 to 26.00, when LDI was increased by 8.3% daylighting performance was reduced to 85%~95%. The simulation results also showed that for all the working hours during day times, except for 4 o'clock on the winter solstice, the light ducts having the LDI lower than 13 provided enough daylight for conference which requires illuminance class F. |