I am trying to make a shoebox building zone that consists of a south-facing window, and the domain is subjected to solar radiation. In this model, there is only one domain presented. As you can see, solar loading is only present on the inner surface of the walls where the solar ray enters the domain and land on the opaque surface. However, the exterior surfaces, the side that faces the do not receive any solar radiation. The walls have been set to shell conduction. I want to simulate the solar loading on the external walls so that I can take into account the effect of solar radiation being absorbed by the external surfaces and the absorbed heat is then diffuse inward. Does anyone know how to set it up so that the external surfaces are also subject to solar loading?