Masaharu TAKIZAWA, Takashi KURABUCHI, Daisuke NARUMI, Toshihiro NONAKA and Ryo TAKANO For healthy living and energy conservation, architectural design which promotes natural ventilation is one of the effective measures. However, it is often difficult to effectively utilize natural ventilation in the city because of the difficulties in predicting the wind direction angle and problems of extremely narrow building intervals. To address these problems, this study focuses on a use of residential ventilation tower in order to effectively utilize the renewable energy resources available overhead without using any power or moving parts. In this paper, in order to quantitatively evaluate the ventilation performance of a residential ventilation tower, size of ventilation towers with equivalent ventilation resistance as through the existing wall face openings was calculated. From the results of wind tunnel experiments and CFD simulations, then, it demonstrated that utilizing the ventilation tower would promote ventilation regardless of wind direction angle and density of the cities.