Measurement prototype for fast estimation of building wall thermal resistance under controlled and natural environmental conditions

Most of the methods for in situ measurement of the thermal resistance of building walls implement passive approaches requiring long measurement times and specific environmental conditions. In the literature, different active approaches have been studied but they remain limited in terms of applications and do not systematically lead to short identification times. This article that follows a previous numerical benchmark study presents a new measurement prototype using a lamp box which heats up one of the surfaces (typically the interior surface) of the wall to be characterized. The use of an aluminum plate placed in contact with the wall face subjected to thermal excitation enables the homogenization of the heat flux transmitted to the wall. Three inverse procedures are implemented to estimate the thermal resistance of the studied wall. The originality of this work comes from an exhaustive measurement campaign. On the one hand, four types of wall among the most common in France, i.e. Internal Insulation Wall, External Insulation Wall and Wood Frame Wall specially built for this study and a Single Concrete Wall located in a real building, were investigated. On the other hand, the use of different climatic chambers made it possible to generate many different environmental conditions (constant, variable and natural). The results highlight the possibilities offered by this in situ experimental device for estimating in a few hours (6 to 10 h) the thermal resistance of the wall studied or of its first layers, as well as the limits depending on the type of wall and the environmental conditions. Some operational recommendations are also provided: avoiding thermal bridges, solar protection in case of strong sunlight on the exterior side of the wall and location of the device on the exterior side in the case of the External Insulation Wall. (c) 2022 Elsevier B.V. All rights reserved.