Analyzing thermal performance of building envelope components using 2-D heat transfer tool with detailed radiation modeling

THERM is a freely available, user-friendly twodimensional heat transfer model for analyzing the impacts of thermal bridges in building components such as windows and doors. This paper begins by describing THERM as a tool for analyzing individual building components as well as envelope assemblies. The significance of THERM’s detailed radiation heat transfer model, which incorporates a view factor based radiation heat transfer algorithm, is then presented in detail. Radiation heat transfer plays a significant role in projecting building components (i.e., Greenhouse windows, skylights, etc.), and projecting wall sections. The difference between results using a traditional black body assumption and the detailed radiation model can be as high as 30%.