Numerical Analysis and Modelling of Heat Transfer Processes through Perforated Clay Brick Masonry Walls

The aim of this study is to analyse the thermal behaviour of walls corresponding to perforated clay brick masonry layers. The complexity of this work relies on the effect of all heat transfer mechanisms simultaneously; therefore, apart from conduction through the solid material, the propagation of heat depends on convection and radiation mechanisms in the region of the air cavities (pattern of small holes). Evidently, the geometry of perforated bricks and mortar joints of the brickwork, as well as the thermophysical properties of building materials, can modify significantly the evolution of the heat wave under specific boundary conditions at both external/internal sides of the examined layer (ambience). Furthermore, the dynamics of the actual heat flow are affected by the values of thermal-emissivity at the exposed surfaces of the brick holes. In this study, several of these issues are analysed in order to expose their influence on the thermal response of perforated clay brick masonry walls. The transient thermal analysis was carried out by employing the finite element method and by adopting a well-known CFD program focused on heat transfer processes. Secondly, the investigation has been extended to determine the corresponding thermophysical properties of an analogous solid layer (same thickness) that can produce an equivalent heat wave excitation at its interior surface. The resulting values can be useful to promote the building design and diminish the uncertainties regarding the heat flows through building envelopes; besides, assessing precisely the thermal behaviour of building configurations is essential, since the calculation of energy requirements through buildings has become of increasing importance lately.