Effect of Temperature-Dependent Sorption Characteristics on the Hygrothermal Behavior of a Hemp Concrete Building Envelope Submitted to Real Outdoor Conditions

Hemp concrete has been used more and more in building construction because hemp is a renewable plant, recyclable and does not degrade within time. Up to now, many simulation tools use the sorption isotherms that describe the relationship between relative humidity of air and the moisture content to predict the humidity in porous materials. However, the sorption capacity of material depends on temperature. The objective of this paper is to study the impact of the temperature dependency of the sorption curves on the hygrothermal behavior of a hemp concrete building envelope. Numerical models to describe the coupled heat and mass transfer in porous materials are presented and validated against experimental data. In addition, the effect of temperature-dependent sorption on the hygrothermal profiles of a hemp concrete wall submitted to outdoor real conditions has been conducted. The results show that taking the influence of temperature on the sorption characteristics into account is necessary for better prediction of the hygrothermal behavior of a hemp concrete building envelope.