The current paper numerically examines the location of outlet ports and its influence on fluid flow and thermal distribution characteristics of a building cooled by passive cooling using computational fluid dynamics. A single rectangular room with a 1.5 aspect ratio and an inlet located at the left-bottom side of the room is investigated. Three locations of outlet ports are considered for the study: opening on the top of the left wall, right wall, and upper horizontal wall, respectively. The vertical walls are considered adiabatic, whereas the other walls are presumed to be hot walls. Cold air is introduced from the inlet and gets out of the room through the outlet. the flow of fluid in the room is administrated by Navier Stokes equation, which is solved by the Finite-Difference-Method(FDM) adopting the Alternate direct implicit Scheme. The medium of flow in the room is air. Its Prandtl number is 0.71. The flow regime is studied in the laminar range. The study shows that when the exit is at the top of the left wall, cross ventilation is not effective. Fluid circulation is created at the right half of the room. The diagonal placement of the ventilation port is effective in distributing the cool air in the cavity, with each increase in Rayleigh number, the convection inside the enclosure increases. For Ra ≥105, the heat from the wall is not well transferred to the middle of the cavity for positions of outlet diagonally placed on right and center of the top wall. These understandings help in energy-efficient and better design of ventilation port locations inside the buildings.