Experimental unsteady characterization of heat transfer in a multi-layer wall including air layers—Application to vertically perforated bricks

Vertically perforated bricks were developed with a view to building environmentally friendly houses since they make insulating materials unnecessary. By an experimental approach, this study proposes to analyze the propagation of a temperature signal in this kind of brick, in order to characterize the thermal inertia of the brick. The steady-state knowledge is completed by the determination of properties like influence functions or characteristic depth concerned by a surface temperature variation. This allows to validate a simple unsteady surface model to be validated for this heterogeneous material which is classified as an insulating structural material. Furthermore, this study supplements the steady-state knowledge in local heat transfer through the air layers of the brick. Indeed, it is verified that convection heat transfer can be ignored in an unsteady heat transfer in this kind of brick, even in extreme conditions such as a sudden temperature fall.