Natural ventilation in steel buildings depends critically on the design of internal spaces and the size and placement of openings in the buildings. The following should be considered:

· To maximize wind-induced ventilation, sit the ridge of the steel building perpendicular to the summer winds. To approximate wind directions, refer to data contained in “wind rose” diagrams available at the National Oceanographic and Atmospheric Administration (NOAA).

Steel buildings are best sited where summer wind obstructions are minimal. A windbreak of evergreen trees planted around metal structures, are useful in lessening cold winter winds that typically come from the north. If designed properly, windbreaks can reduce the cost of heating and cooling, bringing down energy consumption.

· Natural ventilation is applicable to steel buildings that are narrow. Distributing fresh air to all portions of a wide steel building is very difficult. Steel buildings that have a maximum width of 45 feet can be naturally ventilated.

· Each room should have two openings, one for supply and one for exhaust. The exhaust should be preferably located high above the inlet to maximize the movement of air into and out of the building. Windows should be placed across the room so as to balance each other to maximize airflow within the room. This design also minimizes obstructions to airflow within the room.

· Ensure that all window openings are operable by the building occupants.

· Make provision for ridge vents. A ridge vent is an opening installed at the peak of a sloped roof that offers a good outlet for both buoyancy and wind-induced ventilation. It is important that ridge vents are free of obstructions to allow air to flow freely out of steel buildings.

Source: http://www.wbdg.org/resources/naturalventilation.php#