The objective of this work is to present a zonal model to predict the spatial heterogeneity of gaseous pollutants in confined spaces. It has beendeveloped as a set of TRNSYS components, with the thermal and flow fields model decoupled from those describing the dispersion of contaminantsto limit numerical costs. Interactions between building materials and contaminants are taken into account by means of a deposition velocity modelfor inorganic gases and a linear adsorption/desorption model for volatile organic compounds (VOCs). The applicability of the zonal model isshown by studying the impact of building materials on the dispersion of two contaminants, ozone and toluene, in a typical conditioned office space.The case study results indicated that selecting building materials to reduce occupants' exposure can be an efficient passive solution for ozone but notfor toluene. They also suggest that, for a well mixed environment, the single zone model overestimates the effect of deposition onto building materialsfor ozone, and the VOC linear adsorption/desorption zonal model does not give better predictions than the single zone model.