| Title |
A study on the Calculation of Sky illuminance using Computer Graphics |
| Abstract |
Exterior Horizontal or Vertical illuminance is the most important element of daylight avaliability which is a principal factor for evaluating daylight performance in a building. There are three approaches to determine horizontal illuminace, i.e.,direct computation by empirical equation, conversion from horizontal irradiances by multiplying by luminous efficacy and by integration of sky luminance. Sky luminance integration method has some advantages:it makes us possible to calculate horizontal illuminances hourly and with consideration of exterior obstructons. To integrate sky luminance over the entire sky vault,elevation angle and skyline should be determined first. Utilization of computer graphics algorithm makes it easier and more useful. In this study, by using sky luminance integration method in conjunction with computer graphics algorithm such as line intersection and user coordinate system, exterior horizontal and vertical illuminance in clear and overcast sky condition are obtained at the center point of three types of window(horizontal, vertical and tilted window)in terms of solar illuminance and sky illuminance.These graphic outputs are useful to apply this method to computer graphic methods easily. |