Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The shading algorithms date back to BLAST and TARP which only supported rectangles and triangles. EnergyPlus 1.2.1 extended these algorithms to allow for more general polygons, but support for concave surfaces and holes was not implemented. The main function for this is SolarShading::DeterminePolygonOverlap. I don't know how difficult it would be to add this capability.
From the Engineering Reference (v8.5).
Polygon Clipping Algorithms
Two methods for polygon clipping (treating of overlapping shadows) are currently in use in EnergyPlus.
The original EnergyPlus method for polygon clipping is a special version of the Weiler-Atherton model (Weiler, Atherton, 1977). It was developed to be sufficiently general to clip concave polygons with holes. The implementation in the current version of EnergyPlus, however, does not support concave shadowing surfaces or holes.
