Assessment of hygrothermal behaviour of an experimental timber-framed house

The context of very high energy efficiency and the development of bio-materials bring new questions about heat and mass transfer and their impact on the actual energy performance, comfort, health and the risk of components degradation. This is particularly true for old buildings built before 1948 with very hygroscopic materials. If the humidity has an effect on the thermal performance of the building envelope, it influences also the interaction between the building and it constituent materials and the air indoor quality, and therefore, the effects on the comfort and occupant health (risk of mould growth). Indeed, the preservation of envelope components is based on a hygrothermal balance of parts that constitute it. Any intervention on buildings that shifts this balance can cause disorders. In particular, a thermal insulation of walls when it's poorly designed or badly implemented can generate condensation in walls or on their surfaces and cause structural pathologies. To provide some answers to these questions, an experimental timber-framed cell was constructed. It allows the study of both global and detailed hygrothermalbehavior at both wall and building scales. It is a timber-framed and cob cell with two zones (dry and wet) of about 16m² with two mechanical systems of ventilation (double-flow ventilation and Positive Input Ventilation). The aim of this paper is to present the hygrothermalbehavior of this cell without and with insulation under several boundaries condition. The experimental cell and its monitoring set-up are presented. Four configurations are studied: Case1: without both ventilation and insulation; Case2: with mechanical ventilation and without insulation; Case3: with both mechanical ventilation and internal thermal insulation; Case4: without ventilation and with internal thermal insulation. The indicators of hygrothermal comfort and of risks of pathologies related to humidity are calculated and compared for the studied configurations.