The buildings in the metropolitan cities are very big while the portions in that buildings are very small, like one room or two rooms, air is blowing from different-different directions so may be your flats has not proper natural air ventilation systems and due to this the temperature in the building is differ from place to place, because of temperature difference, the air inside the building is more or less dense than the air outside the building. But if there is an opening high in the building for throw the inner air to outside and another low opening in the building for outer air to come inside the building then a natural flow of the air will be caused where fresh air will enter from the one sides and the hot humid air will rise and exit through the opening at the top, but in the metropolitan cities this type of the system is impossible so we needs to think about the artificial ventilation systems. Golden Turbovent rotate air that is inside your room and creating a higher rate of outflow of air. Wind driven ventilation system is a combination of both natural and forced air ventilation system. It is a free spinning roof ventilator which works on wind energy. It functions as a natural air ventilator when there is a difference in thermal or wind pressure between the inside and outside of the building which forces the air to move through the opening of the ventilator. It also acts as a forced ventilation system when the air ventilator rotates to create a negative pressure within the building. Cool air from outside the building will rush into the negative space within the building in order to maintain an equilibrium condition.