The building energy simulation program, EnergyPlus, was used to identify the best setting of UFAD system and compare it with the existed UFAD and the conventional ceiling based air distribution (CBAD) system. The simulation results show that setting of room thermostat at 26 ¡ãC and supply air temperature at 18 ¡ãC provides the best efficient UFAD system. Due to improper operation of the tested UFAD system, its actual consumption is found to be higher than the best simulated UFAD by 23-37 % during July to October. Also, the simulation results show that the HVAC demand of UFAD is lower than CBAD by 37-39 % during July-September and 51 % in October.