Air Curtains Information
An air curtain, sometimes called an air door, slows air and airborne contaminants from moving between environments. Mounted over an entrance to a building, walk-in refrigerator, or any place where a significant temperature gradient exists, a downward facing fan blows a stream or "curtain" of air that slows horizontal air movement.
By creating forceful turbulence they are effective at reducing insect and dust intrusion and slows down hot or cold air loss through convection. Air curtain effectiveness is dependent upon wind force, temperature differences, and pressure differences. Air curtains work best when the pressure differential between the inside and outside of the curtain is as close to neutral as possible. Efficient air curtains utilize a high velocity, top down flow with air recovery through a duct system that recirculates the air to the fans (thus keeping some of the air's momentum). Air curtains are never perfect and should are a means of mitigating air flow; they do not offer a perfect seal.
The benefits of air curtains include energy savings due to a reduction in heat transfer when doors are opened, though obviously a closed and well-sealed door is more effective. By reducing the costs of a building's heating or cooling systems, air curtains will often pay for themselves within a few years of purchase.
Air curtains are employed where doors are frequently used or must remain open for extended periods of time, such as the entrance to an office building or the loading dock of a factory. Cold drafts can be greatly reduced by heated air curtains and are often used in customer or employee entryways, airplane hangars, drive-through windows, and other similar applications.