The master-planning of the office complex comprises an Office Building, a Staff Quarter, Garage, Guard House and Canteen. Since the Hetauda Municipality is situated at hot and humid climatic zone, solar energy has been used for cooling of the office building. Due consideration has been made that the occupant of the building is an governmental office and dedicated staff will not be available for running electro-mechanical equipment. Therefore, the cooling system has been developed such that even an office boy (peon) can operate it. A simple solar chimney system has been designed. Once the air inside eight numbers of solar chimneys (painted in matt black color) heated, the hot air will flow upwards. This action in turn will develop draught system for creating pleasant breezing in office rooms below. In order to create cool breezing, wide verandahs are designed as cooling zone at west and east end of the building. At first stage, hot air outside will start cooling down once it enters shaded cooling zone and at second stage the air continues to cooling down with breezing effect inside office rooms as it flows through louvers at partition wall to next room. The height of the Solar Chimney has been worked out such that it will create natural air draft system in the office rooms at night or when there will not be sun shine. Thermal mass phenomenon has been considered for night time. It is obvious that at mid night the air temperature will be considerably low and due to the chimney effect (height different) the cool air flow will cooldown all walls, floor, ceiling and furniture in the office room. Thus, due to thermal mass effect, the office room will remain cool at initial office hour. During winter time the solar chimney can be closed by a trap door.