This paper describes the prediction method of concentrations around buildings by wind tunnel simulation. The predicted concentrations are compared with the field measurement data under neutral atmospheric condition, and the prediction accuracy is investigated. Wind tunnel experiments for the concentrations around models are carried out for several wind directions. The predicted concentrations are derived by the superposition of the weighted concentrations which are based on the probability distribution of wind direction. Two probability distributions, which are normal and the observed distribution in the field experiments, are applied for this prediction. Results indicate that the prediction accuracy is improved 15 % in comparison with the ordinary method without considering the wind direction distribution. Consequently, the concentration difference errors are reduced to 40 %.