The aim of this paper is to create better room climatic conditions during reducing the room air temperature with the help of summer night ventilation. This study is carried on Aswan. Aswan lies in the biggest desert in south Egypt, where the climate is sever dry and hot. Calculations were done on a building model. A comparative study was held between Islamic, traditional and modern buildings to obtain the effect of night ventilation on the room temperature. The calculation is carried each hour, each day allover the year. The results are plotted for a representative summer day. Summer night Ventilation of 5 h-1 and 10 h-1 of the room air, between 20 h in the evening and 8 h in the morning, reduced the air temperature in a modern building ca. 5 K and 7 K consequently. The room air temperature in the modern building reached ca. 36 °C and 34 °C with these night Ventilation consequently, while the room air temperature without venting and the maximum outside air temperature were ca. 41 °C. This ratio of air change is achievable through opining windows and Doors, i.e. through natural ventilation. The minimum outside air temperature was about 26 °C, which means, that A more temperature reduction is reachable through architectural elements, which encourage the air movement or air suction or movement with a ventilator, i.e. hybrid cooling.