Indoor thermal environment of a 3-D ventilated room was studied by computational fluid dynamics to understand correlations between heat generation, ventilation velocity and thermal sensation indices. The existence of a thermal occupant was found to produce thermal plume approx 15% stronger in magnitude than that from an unoccupied room. With second thermal occupant, there has further temperature increase of maximum 6.5%, equivalent to an increase of PPD value by 8.6%, for which occupants would normally feel uncomfortable. Thus, an increased flow ventilation rate (>0.7 m/s) would be required, in order to keep the same thermal comfort level of the room. (C) 2014 Elsevier B.V. All rights reserved.