Sensitivity analysis of thermal predictions to the modeling of direct solar radiation entering a zone

Because of high computational costs of computational fluid dynamics multi-zone energy simulation is currently appraised. Yet, the use of empirical correlations to predict interior convective heat transfer (CHT) limits the reliability of building comfort and energy analysis. As most of these convection algorithms depend, partially, on the temperature difference between the concerned surface and the air, the influence of the modeling of incoming direct solar radiation is studied. Simulations of summer comfort in a night cooled office room in Belgium are carried out in TRNSYS using different convection algorithms and four methods to model the distribution of solar radiation. This work demonstrates that the influence of the modeling of incoming solar radiation on the predicted thermal comfort and energy demand is inferior to the choice of the CHT correlations. Therefore, before putting considerable effort in the modeling of direct solar radiation, an accurate approach of the CHT is regarded necessary