Given the large impact of the building sector on the final energy demand, special interest lays in passive cooling techniques, such as night ventilation. Unfortunately, a lack of understanding concerning the coupling between the ventilation air and the thermal mass by night stands its widespread application in the way. Therefore, the authors of this paper investigate by computational fluid dynamics turbulent mixed convection cooling in a rectangular enclosure – resembling a night ventilated landscape office. Based on the 2D Annex 20 test case, four different orientations of the inlet and outlet are considered while varying the Archimedes number – ranging from forced to mixed convection. Also the location of thermally massive elements is varied. Locating the inlet and outlet at the top of the room induces the highest convective heat transfer. Meanwhile, locating the thermal mass at the floor has more potential than at the ceiling
