ABSTRACT Luminaire dirt depreciation (LDD) data were evaluated for seven luminaires from three different project sites in Philadelphia, Pennsylvania, Minneapolis, Minnesota, and Yuma, Arizona. In each case, the luminaires were removed from the installation, carefully packaged and transported to a photometric testing laboratory, and then tested in the “as-is” or dirty condition, cleaned, and retested. In terms of light output, the results showed that the IES RP-36-15 method for estimating LDD was applicable to the light emitting diode (LED) luminaires evaluated. General claims of lower levels of dirt deprecation (or higher LDD values) for LED luminaires than for luminaires using conventional light sources were not supported by the test data for the LED luminaires in these three projects. Though the overall measured lumen depreciation due to accumulated dirt closely matched IES estimates for LDD, the data indicated that the accumulated dirt on the luminaires dramatically altered the luminous intensity distribution of the luminaires, with reductions in intensity of more than 25% at peak angles. These effects on luminous intensity distribution are not accounted for in IES LDD estimates.

中文翻译：

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灯具污垢折旧 (LDD)：来自多个外部照明项目的现场数据

摘要 对来自宾夕法尼亚州费城、明尼苏达州明尼阿波利斯和亚利桑那州尤马的三个不同项目地点的七个灯具的灯具污垢折旧 (LDD) 数据进行了评估。在每种情况下，灯具都从安装中取出，仔细包装并运送到光度测试实验室，然后在“原样”或脏污条件下进行测试、清洁和重新测试。在光输出方面，结果表明用于估算 LDD 的 IES RP-36-15 方法适用于所评估的发光二极管 (LED) 灯具。这三个项目中 LED 灯具的测试数据不支持 LED 灯具比使用传统光源的灯具具有更低的污垢折旧水平（或更高的 LDD 值）的一般说法。尽管由于累积污垢导致的整体测量流明衰减与 LDD 的 IES 估计值非常匹配，但数据表明，灯具上累积的污垢显着改变了灯具的发光强度分布，峰值角度处的强度降低了 25% 以上。IES LDD 估计中没有考虑这些对发光强度分布的影响。