Heat, air and moisture transfers have a significant influence on indoor ambience and affect both temperature and hygrometry values and energy performance of buildings. Furthermore, high levels of humidity may lead to severe pathologies in building walls in addition to tamper indoor air quality and hygrothermal comfort. Sorption hysteresis phenomenon is responsible for the moisture accumulation in porous building materials, and leaving it out in hygrothermal modelling would result in an incorrect water content value.The present work aims to highlight the influence of the sorption hysteresis phenomenon on heat and moisture transfer in expanded polystyrene concrete. In order to achieve this, a coupled heat and mass transfer model will be elaborated, taking consideration of sorption hysteresis phenomenon. Experimental protocols will be conducted to highlight the hysteresis in the materials, and the results will be compared to those of the numerical simulations. A simple hygrothermal transfer model without including hysteresis will also be used in the numerical simulations so that it is compared to the developed model. Experimental results show that considering the hysteresis phenomenon allows to better apprehend the hygrothermal behavior of building materials, and neglecting it leads to important differences sometimes reaching 28%.