Thermally activated building system is not only energy efficient but also provides better thermal comfort compared to the conventional cooling systems. In this paper, COMSOL Multiphysics, a computational fluid dynamics tool, is used to simulate the performance of a cooling tower coupled with thermally activated building system for the hot and dry summer climatic conditions of New Delhi. The effects of three operating parameters, namely, temperature and inlet velocity of water and the number of cooling surfaces (area), on the performance of the system have been investigated. The results indicate that increasing the water inlet temperature from wet bulb temperature (WBT) to WBT + 6℃ would increase the operative temperature of the indoor space, a thermal comfort index, by 2℃. The increase in water inlet velocity from 0.2 to 1 m/s would decrease the diurnal average of operative temperature by 1.4℃. If only the roof was cooled, the diurnal average of operative temperature was 36.7℃. The diurnal average of operative temperature was reduced by 5.7℃ if all the building fabrics were cooled. In this case, with pipes connected in series from the floor first to walls and then to roof resulted in 2.9℃ lower operative temperature compared to that in the reverse sequence. Hence, the sequence in which the fabrics are cooled would have an appreciable influence on the performance of thermally activated building system. © The Author(s) 2017.