This study optimizes the performance of displacement ventilation (DV) system aided with chair fans (CF) for providing acceptable thermal comfort and indoor air quality (IAQ) in office space. A 3-D computational fluid dynamics (CFD) model coupled with a bio-heat model was used to predict the airflow, temperature, and CO2 concentrations fields as well as the occupant segmental skin temperatures for local and overall thermal sensation and comfort evaluation. The CFD model results were validated experimentally in a DV conditioned space using a thermal manikin seated on a chair equipped with fans. Simulations were performed using the validated CFD model to determine the fans optimal height from the floor. For a pollution source located at 1.0 m from the floor, it is recommended to place the fans at 30.9 cm above the floor at fans total flow rate of 12 L/s while for a pollution source located at 03 m from the floor, the optimal height of fans is at 30.1 cm above the floor at fans total flow rate of 12 L/s. Compared to stand alone DV system, energy savings were 20.6% and 11.6% for fans' optimal heights of the sources placed at 1.0 m and 0.3 m, respectively. (C) 2016 Elsevier B.V. All rights reserved.