NUMERICAL STUDIES OF TURBULENCE EFFECTS IN CROSS-FLOW VENTILATION by Mina Mohammadmirzaei Natural ventilation systems reduce a building's utilization of energy in terms of electricity consumption and fossil fuel usage. Many factors including building shape, window style and configuration, and wind turbulence impact the efficacy of natural ventilation. In order to investigate the effect of turbulence on natural ventilation, twelve different conditions of a cross-flow ventilated room were studied numerically using computational fluid dynamics. Wind tunnel studies of tracer gases in a scale model were used to validate the numerical results. A comparison of twelve investigated cases shows that air circulation inside a natural ventilated room is only slightly affected by turbulence, and that the impact is strongest at low velocities. However, the result is small compared to the impact of wind velocity, and the relative impact of turbulence approaches zero at high velocities. Therefore, using fans to increase flow velocity results in better air replacement compared to using retrofitting geometries.