Paper Conference

Proceedings of Building Simulation 2011: 12th Conference of IBPSA


Comparison of models for the derivation of diffuse fraction of global irradiance data for Vienna, Austria

Sokol Dervishi, Ardeshir Mahdavi

Abstract: To compute the irradiance intensity on building surfaces, information on both direct and diffuse component of solar radiation necessary. Available measured data are, however, typically restricted to global horizontal irradiance. There have been thus many efforts in the past to develop algorithms for the derivation of the diffuse fraction of solar irradiance. In this context, the present paper compares eight different models for estimating diffuse fraction of irradiance based on a database of measured irradiance data from Vienna, Austria. These models generally involve mathematical formulations with multiple coefficients whose values are typically valid for a specific location. Subsequent to a first comparison of these eight models, three better performing models were selected for a more detailed analysis. Thereby, the coefficients of the models were modified to account for Vienna data. The results suggest that some models can provide relatively reliable estimations of the diffuse fractions of the global irradiance. The calibration procedure could only slightly improve the models’ performance. Keywords: irradiance, diffuse irradiance, models, simulation, measurement
Pages: 765 - 771