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A. Mahdavi, S. Dervishi:
"A Simple All-Weather Sky Radiance Model";
Talk: BS2013 - Building Simulation 2013, Chambery / Frankreich; 2013-08-25 - 2013-08-29; in: "Building Simulation 2013 - 13th International Conference of the International Building Performance Simulation Association.", IBPSA (ed.); IBPSA, (2013), ISBN: 978-2-7466-6294-0; 916 - 922.

This paper presents a simple all-weather sky radiance model (diffuse component). The model development was motivated by the intention to find a balance between the model's simplicity and ease of use on the
one side and predictive capability on the other side. To develop the model, measured data collected at the microclimatic monitoring station of our institute (the Department of Building Physics and Building Ecology of the Vienna University of Technology)
was deployed. To formulate the model, a formalism based on the concept of irradiance coefficient was used. Irradiance coefficient denotes, in percentage, the fraction of global horizontal irradiance
attributable to a distinct sky patch. Thus, the developed model can be used to estimate the contributions of a set of discrete sky patches toward the overall global horizontal irradiance. The
irradiance coefficient is estimated as a function of a number of salient variables related to sky Clearness Factor (an original function of the sky Clearness Index), angular distance of the observed patch from the sun patch, and observed patch altitude. The
performance of the resulting model was assessed against a separate set of measurements. The comparison displayed good agreement.

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