In-situ assessment of the thermal performance of earth masonry construction

Abstract

The interest in traditional earth constructions has grown in Europe since a few years. This growing interest can be attributed to the fact that earth has among other qualities a good capacity for the hygrothermal regulation inside a building. This well-established ability of earth to store and manage heat and moisture has been extensively studied in the past at the material scale. However, the evaluation of the building envelop performance is rarely achieved in practice. This study presents an evaluation of the thermal performance of earth masonry construction based on in-situ measurements under real conditions of exposure. The construction consists of a single unoccupied room with habitable surface area of 12.9 m2 located in Canohès in the Southern France. Firstly, the airtightness of the envelop was quantified with the blower door test. The air permeability results indicated a very good level of airtightness. Then the thermal insulation of the envelop was measured according to the ISABELE method (In Situ Assessment of the Building EnveLope pErformances). The latter is a method developed by the CSTB to deduce the transmission heat transfer coefficient of the building with its uncertainty within short unoccupied period (few days). The results of the different ISABELE tests demonstrated that the total thermal insulation level of the tested envelop could be classified as good to average according to the scale of the building heat loss coefficient (Ubat) of the French Energy Performance Diagnosis. The results of the ISABELE tests were confirmed by the outcomes of a Coheating test conducted during a long period of 3 months. This study gives encouraging results on the application of the ISABELE method on earth masonry buildings to deduce the thermal performance of their envelope quickly, instead of a complete Coheating test which can be too long to apply in practice.