Simulation of heat and moisture flow through walls covered with uncoated medium density expanded cork

This paper evaluates the influence of the solar heat flux, temperature, and relative humidity on OSB and concrete walls covered with uncoated medium density expanded cork. A boundary element numerical model was used to simulate the coupled heat and moisture transfer through the multi-layer porous solid walls. The expanded cork hygrothermal properties were determined experimentally. After experimental validation of a building solution using a hotbox, numerical simulations were performed to evaluate the effect of the abrupt change in relative humidity and temperature. It was concluded that the relative humidity variation is only relevant when there are significant weather changes during the course of the year. Thus, the summer and winter conditions of Braganca (Portugal) and Seville (Spain) were selected to illustrate the hygrothermal behaviour of the walls. Different thicknesses of expanded cork were simulated. The results show that the impact of the short-term environment moisture variation is limited to the outer surface layers. It was also found that the moisture along the medium density expanded cork coated wall is only high when the outer moisture is high and remains high for a long period of time.