Exceedance probability analysis was often applied as an effective method for assessing local wind environment in a street canyon, in which the effects of wind from each direction are comprehensively taken into account. In this present study, a new method by means of exceedance probabilities was proposal, with the aim to evaluate the overall ventilation performance in specific spaces within the street canyon (evaluation space), based on two ventilation indices, local air change rate and average kinetic energy, instead of using the commonly adopted wind velocity. In this method, the ventilation indices are derived from CFD simulation for each azimuth before the calculation of exceedance probability. A three-dimensional dry-area model was used as an illustration of this method. Several key factors, including orientation of dry-area, geometrical configurations, as well as statistical wind data were further investigated with the calculated distributions of exceedance probabilities.
