In this paper, the results obtained from the analysis of the heat and mass transfer of an Air-Carbon Dioxide mixture (CO2) inside a ventilated cavity in laminar flow regime are presented. A ventilated cavity is usually the way to model a ventilated room as a first approximation. Different configurations of the cavity were analyzed regarding the location of the mixture outlet gap, in order to study the thermal behavior and the air quality inside the cavity considering three different values for the CO2 contaminant source (1000, 2000, 3000 ppm). The air inlet gap is located on the lower side of the right vertical wall of the cavity. The inlet air velocity is a function of the Reynolds number (10 <= Re <= 500). The location of the mixture outlet gap was considered in four different positions: Case A, the outlet gap is on the upper side of the left wall; Case B, the outlet is on left of the top wall; Case C, the outlet is at the middle of the top wall and Case D, the outlet is on right of the top wall of the cavity. Based on the results, it was concluded that, from a thermal comfort point of view and air quality, configuration D shows the best performance in the interval 50 <= Re <= 100, with an exception for the case when a contaminant source of 1000 ppm is present where configuration C is recommended. This study aims to provide guidelines for construction builders towards better design of buildings in order to achieve better air quality. (C) 2011 Elsevier Ltd. All rights reserved.