DE-79-05-2 -- Energy Conservation with Natural Air Flow through Windows PDF

The need for optimizing energy use in buildings is drawing designers back to some of the basics of natural environmental control. Of the principal elements which govern human comfort, air temperature, humidity, and air movement, the latter is the only one which can be significantly controlled without substantial energy use.

Windows are of primary concern as vehicles for getting air into and out of buildings, and they must be chosen carefully for their air-controlling characteristics. However, windows are only part of'a "system" of air-controlling features which must be used to enhance air movement through the "living zone" of a building where it can cool occupants.

Air is moved by pressure differences set up as wind strikes a building. The wind moves from high to low pressure. Wind has inertia and it causes friction as it moves.

The location and type of inlet opening (window) determines the pattern of the air entering the building. The size of the outlet opening determines the speed-- the larger the outlet, the faster the air moves.

The location and type of window directs the air as the nozzle of a hose directs water. The air tends to follow the opened window vanes. Other elements such as overhangs, landscaping screen trees, and shrubs can also be used in the control of air movement.