Modelling thermal and aerial behaviour of unconditioned buildings requires an accurate knowledge of the air temperature and velocities fields inside the considered spaces. Furthermore, in ourMediterranean context, thermal and aerial aspects must be considered coupled together, because oftheir very strong interdependence. We have then developed a three-dimensional dynamic modularmodel of coupled heat transfer and airflow calculation. Its coupling with a thermal comfort modelpermits to evaluate the thermal quality of buildings by the prediction of a comfort vote.This paper presents an application of our coupled simulation tool dealing with the influence of apassive solar component, upon the winter thermal comfort of an unconditioned Tunisian building. The results obtained have shown that the zonal modelling approach transcends the limitations of isotherm models to describe realistically the thermal comfort within a building.