CFD Modelling and Thermal Performance Analysis of Ventilated Double Skin Roof Structure

Abstract

Air conditioning is a serious issue in hot areas. The demand to live in more comfortable buildings, which is understandable, has resulted in an increase in energy consumption by air conditioning. However, in Djibouti, one of the world's most expensive electricity countries, this demand is exacerbated by building that is inadequate and unfit for the climate. This paper investigates the design of the roof which is the surface receiving the most solar radiation and which determines the general behaviour of the building. The energy performance of a double skin ventilated roof is modeled and analysed using Computational Fluid Dynamics (CFD). This study looks at Djibouti's climate, which is hot and humid in the winter and extremely hot and humid in the summer. To characterize the flow and heat transfer induced in the ventilated roof in a steady state, roof simulations are carried out using the Ansys Fluent software. The effects of numerous parameters on heat gain through the roof are compared, including the internal emissivity of the upper surface, the thickness of the roof insulation, and the thickness of the vented channel. The energy saving potential is also studied and presented in comparison to the current constructions in Djibouti.