利用系数法计算平均照度.docVIP

17.3利用系数法计算平均照度 照度的计算方法主要有三种方法，即利用系数法计算平均照度、逐点计算法和单位容量法。所谓利用系数μ，是指电光源的光通量通过直射、经墙反射、经屋顶反射等达到工作面S后，能够利用到的光通量Φ1和电光源发出的光通量Φ2之比，称为利用系数。利用系数法适用于均匀布灯的一般室内照明设计计算。 根据已知的建筑面积S、灯具悬挂高度(h)、屋内墙面反射率、电光源的光通量等因素计算平均照度。 17.3.1利用系数定义 μ＝Φ1槷梽───槷梾Φ2(17-13) 如漫射光源利用系数约为0.3，直射光和半直射光约为0.5，如果是旧墙还要再乘0.9。实用中需要分别考虑墙面、地面及屋顶材料的反射系数、灯具悬挂高度和室空间比等因素。 根据墙面材料反射率及室空间比时，利用系数见表17-8，17-9。 配照灯(500W)白炽灯的利用系数μ表17-8泜 ─────┬──────┬──────┬──────┬──────┬── 顶棚反射│70│50│30│10│0 率ρc(％)│││││ ─────┼──────┼──────┼──────┼──────┼── 墙反射率7050301070503010│0 ρw(％)│││││ ─────┼──────┼──────┼──────┼──────┼── 室1│.88.84.80.77│.84.80.77.75│.80.77.75.72│.76.74.72.70│.63 空2│.81.75.70.66│.77.72.68.64│.74.69.66.63│.79.67.61.61│.59 间3│.75.67.61.59│.71.64.59.55│.67.62.57.54│.64.60.56.53│.51 比4│.68.60.53.48│.65.57.52.47│.62.56.50.46│.59.54.49.46│.44 5│.63.53.46.41│.60.51.45.40│.57.50.44.40│.54.48.43.39│.38 6│.58.47.40.35│.55.46.39.35│.52.44.39.31│.50.43.38.34│.32 7│.53.42.35.30│.50.41.34.30│.48.39.34.29│.45.38.33.29│.28 8│.49.38.31.26│.46.37.31.26│.44.36.30.26│.42.35.30.26│.24 9│.45.31.27.23│.43.33.27.23│.41.32.27.23│.39.31.26.22│.21 10│.42.31.25.20│.40.30.24.20│.38.29.24.20│.36.29.24.20│.18 ─────┴──────┴──────┴──────┴──────┴── 配照灯(GGY-400W)高压汞灯的利用系数表17-9泜 ─────┬──────┬──────┬──────┬──────┬── 顶棚反射│70│50│30│10│0 率ρc(％)│││││ ─────┼──────┼──────┼──────┼──────┼── 墙反射率7050301070503010│0 ρw(％)│││││ ─────┼──────┼──────┼──────┼──────┼── 室1│.83.79.75.72│.79.75.73.70│.75.72.70.63│.71.69.67.66│.64 空2│.76.70.65.60│.72.67.63.59│.68.64.61.58│.65.62.59.56│.55 间3│.69.61.55.51│.66.59.54.50│.62.57.52.49│.59.55.51.48│.46 比4│.63.55.48.43│.60.53.47.42│.57.51.46.42│.59.49.45.41│.40 5│.58.48.42.36│.55.47.41.30│.52.46.40.35│.49.44.39.35│.34 6│.53.43.36.31│.55.41.35.31│.48.40.35.30│.45.39.34.30│.29 7│.48.33.31.26│.46.37.31.26│.43.36.30.27│.41.35.30.26│.24 8│.45.34.28.26│.42.33.27.23│.44.32.27.23│.38.31.26.23│.21 9│.41.31.24.20│.33.30.24.20│.37.29.24.20│.36.28.23.20│.18 10│.38.28.22.18│.36.27.21.17│.38.27.21.17│.33.26.21.17