COMPARATIVE THERMAL PERFORMANCE ANALYSIS OF ROOFTOPS WITH ELEVATED CEILING CONFIGURATION

Abstract

In this study, thermal performance of different pitched roofs with elevated ceiling configuration is analyzed and compared. Three different ceiling shapes, viz., cathedral, barrel-vault and A-frame, at the same pitch angle and ceiling material, under winter heating are examined numerically by solving the steady-state air and heat flow problems simultaneously. In all the roofs, the airflow fields show counter-rotating recirculating cells. The multicellular flow field promotes uniform temperature distribution within the enclosures. Heat loss to the attic from the space below increases with the closeness of the hot ceiling to the cold inclined walls. In the A-frame roof, there is uniform convective heat transfer. But in the cathedral and barrel-vault roofs, near the bottom corners, conductive heat exchange predominates. In all, the thermal performance of the barrel-vault is least while that of the cathedral is best. This observation is useful on the application of insulation when using such ceiling shapes.