Effects of Initial Conditions on Simulations of Hygrothermal Transfers Through a Bio-Based Multi-layered Wall Subjected to a Real Climate

This modeling study investigates the effects of the initial conditions on a bio-based multi-layered wall by hygrothermal simulations. Such a study cannot be found in the relevant literature. In a first step, the work consists in numerically generating different climate histories for the studied wall, using two different real climates: a winter and a spring climate. Then, the wall preloaded with these two different climate histories and therefore different hygric and thermal initial conditions is subjected to several cycle of 18 days of the spring climate. This study highlights the significant effects of the initial conditions on the subsequent simulations: strong differences are predicted about relative humidity and water content. Many cycles of 18 days of the spring climate have to be applied to obtain a hygric convergence of the two simulations, i.e., to erase the wall hygric history. The analytic analysis of the results leads to define characteristic times of hygric dependency of about 35–40 days. It appears that the hygric predictions of the simulations become independent of the initial conditions after about three times these characteristic times, i.e., about 3.5 months. Comparatively, the thermal history takes only a few days to be erased.