Fast Computation of Incident Solar Radiation from Preliminary to Final Building Design

Accurate calculation of direct solar radiation with current methods is slow and frequently requires oversimplification of building geometry to obtain expedient performance simulations. This paper describes the use of a fast new method for calculating direct solar gains on architectural CAD models at any stage in design. A pre-processing module computes direct incident solar radiation with high accuracy several orders of magnitude faster than common analytical approaches. The technique is illustrated using preliminary CAD models of two existing buildings that are gradually made more complex through the addition of intricate louvered shading devices, foliage, and adjacent urban structures. Each refinement allows EnergyPlus to calculate much more accurate direct solar gain data with only minimal increase in pre-processing time and no effect on energy simulation time.