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Proceedings of BauSim Conference 2012: 4th Conference of IBPSA-Germany and Austria

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A comparison of luminous efficacy models for the diffuse component of solar radiation

Sokol Dervishi, Ardeshir Mahdavi

Abstract: To perform detailed architectural daylight analysis via simulation, appropriate sky models are needed. In the past, various sky luminance distribution models have been developed. Such models, however, require global and diffuse illuminance data for the relevant location. Measured data on global and – especially – diffuse external illuminance are available only for few locations. Hence, methods are needed that can derive from the more widely available irradiance data the corresponding illuminance data via reliable luminance efficacy models. In this context, the present paper focuses specifically on the problem of luminous efficacy models for the diffuse component of solar radiation. Toward this end, we comparatively evaluate several diffuse luminous efficacy models based on a database of measured diffuse illuminance and diffuse irradiance data from Vienna, Austria. These models typically involve mathematical formulations with multiple coefficients, whose values are derived for a specific location. The evaluation of the different models has been carried out considering all sky conditions from sunny, to partly cloudy, to overcast.
Pages: 117 - 120
Paper:
bausim2012_125