I have two models, both with the same shading surface covering the roof. One model has thermal absorptance at 0.1 (0.9 reflectance), the other model has thermal absorptance at 0.9 (0.1 reflectance). All other parameters are the same. I am simulating using FullInteriorAndExteriorWithRefections.

Why would the Roof Surface Heat Gain be more with a highly reflective shading surface? It must be reflecting building heat back more than the other one is allowing solar radiation through?