Homes and commercial buildings are built with tighter construction standards today. This often turns into a ventilation problem if the building also has any kind of ventilation system, such as bathroom exhaust fans, range hood or a clothes dryer. All of these systems remove air from the home or office, and if the building is not provided with replacement air, sometimes called “make-up” air, the building will have negative pressure. Negative air pressure is a huge problem in a building, because the building will try to find replacement air thru every nook and crack in the building, around doors & windows, and even thru other inactive ventilation ducts. When that happens, the incoming air is often drawn thru dusty or dirty areas, and that unfiltered dirty air is carried into your home or office to settle on furniture or be suspended in the air you breathe. Perhaps the worst example is when you open the door, and a puff of dirty air comes in with the foot traffic. Another problem associated with negative air pressure is that it promotes ingress of soil gases, sometimes containing radon, drawn thru foundation floors by the negative pressure inside.
There are some exotic and sophisticated methods of testing buildings to see if they have a negative air pressure problem that must be carried out by a contractor or engineer. But I am going to give you a simple method you can use yourself to see if you have this problem: On a cool or warm day (so you can feel the air temperature difference), open your front door just an inch or so. Then place your nose in that opening and pay attention. If air is coming in, your nose will feel the temperature difference, and if so, then you have a negative ventilation condition in your home or office. Correcting the problem will probably require a qualified HVAC contractor to diagnose the source and propose a solution to the problem, but at least you can do the test yourself. June 14, 2015
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