Optimisation du confort thermique et de l’efficacité énergétique dans les établissements scolaires : cas d’un climat chaud et aride

Abstract

Ensuring the indoor thermal comfort of buildings while minimizing energy consumption is one of the greatest challenges for designers in the modern era, especially with the current climate and economic crisis. In schools, in particular, providing a comfortable indoor environment has always been a complex issue due, in particular, to the high occupancy and frequent use of this type of buildings. In addition, thermal conditions are considered among the main aspects that influence the health of school’s children which can significantly affect their abilities and academic performance. In Algeria, where three quarters of its territory are characterized by a hot and arid climate, schools are very often marked by the problem of thermal discomfort. In addition, heat stress is generally at its extreme due to the high occupancy rate of classrooms. In this same context, the existing literature has confirmed that energy savings could reach 50 to 75%, using different measures such as the improvement of the building envelope and systems. More specifically, the thermal and energy performance of the envelope depends on the construction choices relating to the architectural elements, in particular the walls, the roof and the openings generally considered as decisive elements in the heat exchanges between the building and its environment. Considering the relatively small number of works devoted to the study of the impact of envelope materials on the thermal and energy performance of school buildings in a hot and dry climate, the present research attempts to fill the gaps in this field and proposes to invest the means to reach the double objective of the thermal comfort of the user and the energy performance of the school building by acting on the material characteristics of the envelope. To do this, a methodological framework has been developed; it is based on three fundamental approaches: conceptual, empirical and numerical. The conceptual approach is based on a review of the literature and a bibliographic research aimed at deepening the knowledge of the concepts related to the subject. On the other hand, the empirical approach was based on in situ measurements combined with surveys and questionnaires to study and evaluate quantitatively and qualitatively the thermal comfort and the energy performance in three existing schools chosen as case studies. The buildings are located in the town of Sidi Okba; IV it was chosen to illustrate three periods of construction and thus different envelope variants differing according to the materials used for the construction of the exterior walls. From this point of view, the establishments taken as case studies have made it possible to carry out a conclusive comparative analysis relating to the influence of the materials of the envelope on the thermal and energy performance of the building and users satisfaction. Finally, a numerical study using the thermal and energy simulation software DesignBuilder and EnergyPlus was carried out with the aim of studying and optimizing the impact of the choice of envelope materials and their properties on the performance of the school buildings. A series of models and scenarios were tested to study the impact of building envelope components (opaque wall materials, insulation, and glazing) and their properties (wall thickness, type and positions of insulation, type of glass and shading factor, surface colors and textures). In the end, the best performing parameters were selected as the optimal solution. The results obtained have made it possible to better understand the interaction between the different elements of the envelope and the impact of their properties on the thermal and energy performance of the school building in a hot and dry climatic context. In addition, the study also highlighted the potential of the different possible combinations of envelopes with respect to the parameters studied, in particular the choice of materials. Finally, the results showed that an appropriate choice of architectural elements and material properties of the envelope taking into account the climatic specificities of the context in the initial stages of the design process, can substantially improve the thermal comfort conditions while reducing the energy needs of the school building