ABSTRACT
Many building regulations are asking for thermal comfort or cooling load calculations under summer climate conditions. The methods indicated for both of these calculations require as input parameters the solar factor (symbolized S-value, or F) of building elements. But for some building elements, like ventilated roofs, there is still no method currently available to assess (via calculations, or testing), the S-values.
This paper shows a method (based on CFD simulations) to calculate the solar factor in such cases. Simulations were done on 3D meshes, under steady state conditions and are taking into account the conduction, natural convection and radiation phenomena present in the attic.
The simulations were first validated against experimental data obtained after testing in artificial climate at Oak Ridge National Laboratory (ORNL). Two cases are analyzed: an US traditional attic and a Cathedral attic. Physical explanations are given for the variations of the calculated parameters.
