Two-dimensional computational simulations are performed to examine the effect of open location on natural ventilation for room with an internal heat source. The room is symmetrically cooled from the sides and insulated from lower and upper walls. The analysis of the fluid flow and heat transfer characteristics of the natural ventilation was carried out by the method of streamline and temperature contours. Three different cases of local open length on lower and upper walls are studied for Rayleigh numbers ranging from 10(3) to 10(5) and open aspect ratio varied from 0.0 to 0.8. The results show that the enhancement of the heat transfer is the greatest at high Rayleigh numbers and open aspect ratios. The best position for the open locations was found out to be on the upper wall as shown in case 3. (c) 2007 Elsevier B.V. All rights reserved.