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In desert regions, the heat gain through the walls is the main cause of overheating during warm period. In the present work, we carry out a study on the influence of the buildings envelop on the internal temperature by using local building materials. The main objective is to determine the temperatures of the mentioned building with various exterior wall configurations. This study aims at assessing also the Grashof number Gr of air layer which is arises throught the study of situations involving natural convection, providing a variety of results.

As a result, this work proves that an optimized building envelope takes into account thermal properties and building materials. The major concept of the thermal rehabilitation is based on the wall composition especially on the calculation of the walls thermal resistances. In the literature, values of thermal resistance of air spaces are very different. In this regard, other factors must be taken into consideration in these measurements such as the mobility of air in all wall elements which contributes as an insulating effect. Indeed, the numerical simulation save a great deal of time and effort in computational terms and showed that the horizontal position of the hollow brick gives the best results. In this sens, a building envelope, as a passive source of energy, is a critical factor. In conclusion, to achieve a better thermal comfort in arid and semi arid regions, a new configuration of the wall has been proposed, it allows to enhance the thermal insulation of the envelop while eliminating thermal bridges. (C) 2013 Elsevier Ltd. All rights reserved.