Thermal energy storage and losses in various types of masonry concrete walls

Abstract

This study investigates the thermal performance of various masonry walls, with and without plaster, for cold zones in terms of their energy storage and loss. Besides a traditional concrete mixture, twenty-five additional mixtures were selected from among 400 mixtures reported in the literature. A computational fluid dynamic (CFD) model that was implemented using ANSYS Fluent is employed here to study the heat transfer from a reference room condition (20 °C) to a cold ambient condition (−20 °C) over a period of 6, 12, and 24 h to facilitate the comparison between different walls. The model was validated using a reported experimental test via a hot plate setup. The results show that among the investigated walls, a mixture with wood shives (WS1) has the maximum stored energy (92 % over 24 h) and the minimum energy loss (8 %) in the total heat transfer from the reference room to the ambient. On the other hand, the minimum energy storage (40 %) and maximum loss (60 %) were observed for hempcrete (HC11). It was found that the combination between thermal properties (thermal conductivity, specific heat capacity, and thermal diffusivity) governs the thermal behavior of each type of concrete. The stored energy inside the wall is drastically influenced by the production of density and heat capacity and secondarily by thermal conductivity, whereas the energy loss is significantly affected by thermal conductivity and diffusivity and secondarily by the heat capacity and density as they raise the wall temperature. It is noted that the plaster reasonably reduces energy loss but has no impact on energy storage.