The impact of the form of roof on the thermal performance in warm-dry climate of Tehran city

The present study investigates the thermal performance in curved (vaulted or domed) roofs and flat roofs in the warm and dry climate of Iran, Tehran. For this purpose, three-dimensions and unsteady state simulations of the domed, vaulted, and flat roofs have been conducted. COMSOL Multiphysics Software has been used to carry out the numerical modelling and evaluate the heat flux and daily heat flow transferred from different types of roofs. The simulation results have revealed that not only the ratio of daily heat flow transferred from curved roofs to the heat transfer through flat roofs has not been influenced by the radius of curvature, thickness, and roofs materials, but also the ratio has been strongly affected by the half rim angle and environment temperature. In comparison with curved roofs, the results have shown flat roofs have consistently outperformed their best thermal behavior in Tehran. In case of the necessity of using curved roofs, use of a vaulted roof with the half rim angle of 50 degrees, revealing the orientation angle of 60 degrees toward the North and a domed roof with the half rim angle of 50 degrees are the best suggestions.

Keywords:

heat transfer , flat roof , curved roof , radiation , conduction , convection