Nowadays, optimization of methods that can reduce energy consumption is efficient for various reasons, such as the increasing mean temperature, the changes in climate, and the shortage of non-renewable energies like fossil fuels. Hence, the stack effect is one of the passive cooling strategies promoting using renewable energy. In this context, Stack ventilation is studied in a hot and semi-humid climate to introduce AEC industry parties. A notable contribution of this study to the existing knowledge landscape involves the integration of stack ventilation (vertical ventilation) with roof channels (horizontal ventilation). Direct and indirect ventilation are scrutinized and compared. Then stack position in the building is investigated for optimizing it in one-, two-, and four-story buildings in Dezful city. Considering being the most frequent residential building type, the four-story archetype has been the main focus of the present study. The models’ behaviors are studied by Design Builder (Energy Plus engine). The CFD (fluid dynamics calculations) module has been used to explore the behavior of air in terms of velocity and temperature quantities by numerical simulation. Findings suggest that indirect ventilation is better than direct ventilation in this climate if individuals do not want to use evaporating cooling strategies inside natural ventilation. Roof channels are particularly effective for collecting and discharging the hot air gathered on the roofs and air circulation within the buildings. The result is appropriate for an architect design in hot regions.