Temperature dependence of sorption isotherm of hygroscopic building materials. Part 2: Influence on hygrothermal behavior of hemp concrete

In the part I of the paper, a temperature effect was experimentally observed for the relative humidity measurement. This effect was correlated to the temperature dependence of the sorption isotherm. In this part II of the paper, the influence of this temperature dependence is investigated on the simulated hygrothermal behavior of hemp concrete. Sorption isotherm was modeled through three approaches: a unique curve (like in WUFI), a temperature-dependent GAB model or the Clapeyron equation associated to the isosteric heat of sorption evaluated in the part I of the paper. Comparison between simulation and experiment is performed for the sample presented the part I of the paper and for a wall subjected either to a slow temperature decrease toward 0 °C or to a fast temperature increase due to solar radiation. Whatever the investigated case, results underline that accounting for the temperature dependence improve the relative humidity prediction. Nevertheless, a great sensitivity to the modeling approach and to the input parameter was observed.