Assessment of hygrothermal performance of hemp concrete compared to conventional building materials at overall building scale

The aim of this paper is to analyse the impact of hemp concrete on the overall hygrothermal behaviour of the building when it used as an infill layer in the envelope of wood-frame structures. Three wall configurations were considered in different climates. Then, a hygrothermal co-simulation approach was used to integrate the model of coupled heat and moisture transfer through multilayered walls in a dynamic thermal simulation tool for the building. The material properties which constitute the input parameters for the model were determined experimentally, according to the hygrothermal state of the material. The results showed that hemp concrete significantly reduces the energy consumption of the building and has better insulation properties than the two conventional building materials: brick and aerated concrete. This is justified by the good hygrothermal properties of this bio-based material, especially its high thermal resistance of 3.08 K.m(2)/W compared to 0.88 K.m(2)/W of brick and 2.28 K.m(2)/W of aerated concrete. In addition, for the three climates considered, the thermal comfort of the hemp concrete envelope is significantly improved. This material also allows stabilisation of relative humidity levels in the ambient air by naturally regulating the hygrometry, to ensure better ambience. The study shows that hemp concrete has interesting hygrothermal properties. Thus, this material can be used massively in the construction field in order to meet the requirements of the current standards which aim to reduce the energy and environmental impacts of dwelling and office building.