Modern diffusers applied in the field of ventilation of rooms are often complex in terms of geometry, including perforated plates, dampers, guide rails, curved surfaces and other components inside the diffuser, with the intention to create satisfying thermal comfort for the occupants. Also connecting ducts can be different for the same diffuser in different situations, affecting the supply velocity profile. It is obvious that simulation of airflow and air temperature particularly in rooms with displacement ventilation is very troublesome, particularly if the near-zone of the diffuser is of interest. Experiments commonly indicate very high turbulence intensities in the near-zone of displacement ventilation supply devices, especially close to the floor where high mean flow gradient occurs. This indicates that the air flow from inlet devices designed for displacement ventilation might be very unsteady; the position of the stream leaving the diffuser and entering the room is changing with time, hence diffusion of momentum and temperature are increased. Also Kelvin-Helmholtz instabilities occurs, resulting in mixing and entrainment of surrounding air into the gravity current. These effects are not captured correctly in RANS simulations, since it is performed with the assumption of time-independent conditions. In this paper URANS simulations were performed for prediction of velocity and temperature distribution close to a complex air supply device in a room with displacement ventilation. The presented study show that URANS with the SST-SAS ￜￜ - ￜￜ turbulence model predicts the air velocities and air temperatures very well close to the air supply device. The URANS computation using the SST-SAS model seems to successfully contribute to the reproduction of large-scale unsteady flow patterns in the near-zone of the supply device, and therefore enable more accurate prediction of the velocity and temperature distributions compared to the steady-RANS computation and dissipative URANS models.