Out Door Units (ODU) of HVAC system are usually placed within balcony of High rise buildings. It is very important that ODU receive adequate cooling within balcony so that temperature of the refrigerant can be kept below critical limits. Placement of ODU at each floor i.e. one above the other creates stack effect. Seasonal variation in wind flow direction along with the stack/buoyancy effect makes the performance evaluation of ODU more complex and it can be achieved using CFD.