This paper presents the indoor air quality performance of a displacement ventilation system ina thermal chamber. This study consists of two sets of experiments. In the first experiment, thethermal chamber was operated under displacement ventilation (DV) mode with the relativehumidity (RH) set at about 65% while the ambient temperature (AT) at 1.3 m height variedfrom 22 to 26C. In the second experiment, all the conditions are the same except that theventilation strategy is changed to mixing ventilation (MV). Tropical subjects were surveyedwith respect to the perceived air quality and Sick Building Syndrome (SBS) symptoms. It wasfound that with an increase in temperature, subjects perceived stronger odour and lessacceptable air quality. Some level of adaptation effect existed in this study as subjectsexperienced less odours and more acceptable air quality after 60 min of exposure at Troom =22C and more acceptable air quality at 26C. On the whole, there is no significant differencebetween DV and MV modes for all subjects votes. DV mode shows a very clear stratificationof carbon dioxide concentration even in a recirculated system as compared to the MV mode.