Transient hygrothermal modelling of coated hemp-concrete walls

The use of hemp concrete, a sustainable material, in constructions is developing significantly. The hygrothermal properties of this hygroscopic porous material promise a good potential in terms of increasing occupants' comfort. In this paper, numerical simulation is used to assess hygrothermal behaviour of a hemp-concrete wall submitted to transient boundary conditions. First, benchmarking the model against a well-documented experimental test case from literature proves the ability of the model to simulate heat and mass transfer in porous building material. Then, experimental results from a full-scale hemp-concrete wall exposed to transient climatic conditions are compared to numerical simulation, and a sensitivity analysis is performed. Good agreement between numerical results and experimental data is obtained for both the temperature and the relative humidity field in hemp concrete. Finally, the influence of coating layer on the hygric behaviour of the wall is investigated numerically. The ability of coating to affect moisture regulation is pointed out and the coating thickness is discussed.