Thermal Insulation Efficiency of Unventilated Air-Gapped Facades in Hot Climate

Abstract

Heat gain and loss through the building envelope is affected by some features such as geometry and orientation, materials’ properties, construction type, and its interface with the outdoor environment. Thus, decisions on envelope design are contained by the objective, whether to advance or limit heat gain or loss, which pertains to the climatic conditions of the construction site. The purpose of this article is to probe the potency of using unventilated air-gapped facades for thermal insulation in hot climates. It is expected to gain positive results regarding the capability of air gap as a thermal insulation in walls of buildings, consequently, reducing the cost of thermal insulation materials and the cost of energy consumed as well. Three different profiles of building facades were selected: a controlled facade with no insulation material, a facade with an air gap as a substitute to the thermal insulation material, and a facade with a polystyrene layer of thermal insulation. The methodology of work depended on building three models in a simulation software for the examined building. Design-Builder Simulation software was repeatedly run to estimate the quantities of energy consumption associated with the usage of the proposed facades through multiple analysis processes. The resulting annual average, annual cooling, and annual heating energy consumption were compared. So that the effectiveness of an air gap as a thermal insulator could be examined. The results showed that unventilated air-gapped facade profiles had a limited efficiency in thermal insulation in hot-humid areas. They showed greater efficiency in reducing heating loads than cooling loads. Reduction efficiency values were twofold more in the winter season than in the summer season. Thus, the role of air-gapped facades as thermal insulators might be more efficient in areas where heating seasons are longer than cooling seasons.