Numerical study of the energy efficiency of the building envelope containing multi-alveolar structures under Tunisian weather conditions

The study of the thermal inertia of buildings is a subject of major interest. The thermal insulation and the nature of the wall sensitively modify the inertia of the building and are the solutions to improve the energy efficiency of the envelope. The roof is well exposed to solar radiation in summer and contributes to significant losses in winter due to convective exchanges. To lead to a thermal comfort, a thermal insulation is necessary. In this context, we carry out a numerical study of the thermal behavior of a building with two zones in variable meteorological conditions for a Tunisian climate (region of Sousse) based on the thermoelectric analogy and using the nodal method as a numerical method. The object of this work is to study the effect of the thermal inertia of the roof equipped with a multi-alveolar structure on the thermal behavior of the air inside the room and on its energy consumption. Taking into account the energy input of occupant, a complete model was established to increase the accuracy of the calculations. The results show that the multi-alveolar structure placed on the outside of the roof reduces energy consumption during the winter period when the alveolar structure is placed in the conductive direction and during the summer period when the alveolar structure is placed in the insulate direction.

Comparative Analysis of the Use of Thermal Insulation Materials Depending on Climatic Conditions and Comfort Microclimate Supply Systems

The use of thermal insulation materials to reduce the heating and cooling demand of the building in order to provide energy efficiency is the main solution. But there is a wide range of these products on the market and, therefore, the choice and application of these materials is a rather difficult task, since many factors must be taken into account, such as environmental safety, cost, durability, climatic conditions, application technology, etc. Basically, comfort microclimate systems are designed based on normative standards, where the thickness of the thermal insulation material is selected depending on the required heat transfer resistance. These values are calculated taking into account climate conditions, that is the duration of the heating period, as well as taking into account sanitary and hygienic requirements. This article discusses the thermal performance of building materials, and also provides a comparative analysis of the use of thermal insulation materials depending on climatic factors and on the system providing comfort microclimate. Based on the calculations by mathematical modeling and optimization, it is advisable to choose the thickness of the thermal insulation, taking into account the capital and operating costs of the comfort microclimate systems. Comparing the optimization data with the normative one, the energy efficiency of the building increases by 50-70% when applying the optimal thickness of the thermal insulation layer, and when the thermal insulation layer is increased, the thermal performance of the enclosing structures has improved by 30%, which contributes to energy saving.