In this study, the investigation of indoor airflow in a sub-scale ventilated room is conducted using two approaches: experimental measurements and numerical simulations. The study concerns the prediction of comfort properties in a sub-scale room. Particular interest is concentrated on the three types of ceiling diffusers namely; square, round and swirl (vortex) diffusers. Basic parameters included air temperature, relative humidity, and air velocity are measured and/or predicated at different inlet conditions to obtain thermal comfort indices such as mean age of air, ventilation effectiveness, and effective draft temperature. Experiments are carried out to find the temperature profile for a certain space at conditions in the range of those expected in daily applications. These data are then used to verify and validate the numerical prediction. The experiments are performed by varying certain parameters and studying the effect of each of these parameters on the air temperature, the velocity profile and hence the thermal comfort.