One sixth of the total energy consumed in Taiwan is for building operation, mainly for summer cooling. The energy consumed for summer cooling can be greatly reduced if naturalventilation can be exerted in Taiwanese urban apartments. To explore the feasibility ofapplying stack ventilation in urban apartments during warm season of Taipei, this studyexamines the ventilation volume induced by the combined wind and stack effect in a twostory building. The examined parameters are roof design, wind velocity, and solar heat flux.This research is conduced in three-dimensional computational fluid dynamics simulations. Itis found that roof type I is able to induce larger ventilation volume when weaker drivingforces are considered. Roof type H obtains larger induced air volume when stronger drivingforces are considered. In this study, the induced airflow volume ranges from 8 to 14 times ofair change per hour. This ventilation volume is much larger than required in a naturallyventilated building when the warm season of Taipei is considered.