People expect the office environment to be as comfortable as possible. Consequently, more and more offices are being equipped with mechanical ventilation or air-conditioning systems. The need for accurate prediction of the air flow in occupied spaces has become even more crucial because, with mechanical ventilation, large quantities of air supplied at a few locations have to be evenly distributed in the space being ventilated. Without adequate air distribution, excessive air movement (draft) can occur in some zones, whereas stagnant air may be present in other zones of the same room. Poor air distribution can affect the indoor climate and degrade the air quality. Until recently, the air movement in a space was predicted from air jet diffusion data and/or testing a physical model, as described by Awbi. Computational fluid dynamics (CFD) is now being applied in the simulation of room air movement. However, in most of the available CFD programs, the radiant heat transfer is simplified or not accounted for when dealing with thermal comfort. Kaizuka and Iwamoto calculated the distribution of a thermal comfort index caused by radiative interaction in a heated room under the assumptions of uniform air temperature and given air velocity. Awbi and Gan andmore » Gan et al. have developed a CFD program called Vortex in which the radiative heat exchange is taken into consideration and that is used to predict the air movement and thermal comfort in both mechanically and naturally ventilated buildings. In this article, the predictions of air movement and thermal comfort in a mechanically ventilated office module and a naturally ventilated office are presented.« less