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Reduction in Light Pollution by Measurements According to EN 13201 Standard

The present modernization of street lighting based on LED technology, with higher energy savings, brings the possibility to oversize the lighting systems. The goal of EN 13201 standard becomes more important, in order to reduce this tendency and, consequently, minimize light pollution. The paper starts from issues of reasonable complexity, such as interpolation and comments related to this operation (EN 13201–3) and continues with observations related to quadratic interpolation, with slightly greater complexity. Underlining the incomplete methodology specified by EN 13201, the paper proposes a more pragmatic approach, based on polynomial interpolation in MATLAB. Following these predominantly theoretical approaches, practical issues related to luminance (EN 13201–4) imaging measurements are revealed. Because the target field is very narrow, additional error sources generated by zoom lens and vignetting are investigated. The geometric implications of imaging luminance evaluation are indicated. The values obtained by the imaging method using a digital camera are compared with the computational parameters as provided by specialized computing programs (DIALux). Today this comparison could be done only for some values and not for the whole field of luminance. The method is clearly superior to the luminance measurement using spot-meters, but at the same time meets the specifications of EN 13201.