Paper Conference

Proceedings of BSA Conference 2015: Second Conference of IBPSA-Italy


Prediction of vertical irradiance on building surfaces: an empirical comparison of two models

Ehsan Vazifeh, Matthias Schuss, Ardeshir Mahdavi

Abstract: Computational assessment of buildings' thermal and visual performance as well as the estimation of buildingintegrated solar-thermal and photovoltaic collectors require detailed boundary condition information regarding sky conditions. Advanced building performance simulation tools for energy and daylight modelling typically rely on high-resolution sky models that provide radiance and luminance values of discrete sky patches. Perez et al. (1993) and CIE (1996) represent instances of such models, incorporated, for instance, in the RADIANCE lighting simulation application. The performance of such models needs to be examined against measured data in various locations. In this paper, we used the RADIANCE application to compute irradiance values on vertical surfaces facing four cardinal for a location in Vienna, Austria. Thereby, both Perez et al. and CIE models were deployed. The simulated vertical irradiance values were compared with corresponding measurement results. The statistical appraisal of the comparison points to limits in the predictive accuracy of both models. The results are discussed to address potential contributing factors and future research needs.
Pages: 27 - 32