A complaint I hear on a regular basis is, “Why is my house so dusty?” The next couple of pieces of conversation that occur are pretty standard. I usually hear people say the air filters get changed every couple of months, we don’t open the windows much and we only have one dog, etc. You get the idea. So the question does become why, when I dust my house, does the dust come back so quickly? The good news is we have answers and better yet, some solutions.
The first thing we are going to look at is a Building Science lite lesson. All of our homes are under very teeny tiny amounts of negative air pressure. The pressure isn’t enough to be felt by humans, you need a very good manometer to measure it, so it’s not at all like how we can feel pressure changes in an airplane. The pressure is, however, enough to make the air inside our homes do very interesting things. Let’s start in the attic. If you look up at the bottom edge of your house around the roof you will likely see rectangular screens going into the attic. These are called soffit vents. These soffit vents allow the attic to pull in outside air. You’ve heard the expression “The house needs to breathe” right? Well, the soffit vents are where outside air gets pulled into the home. That air will then travel down the wall and come out into the home any place it can. Great examples are around light fixtures, electrical outlets, basically anywhere there is a penetration through the drywall into the interior of the home. Even the top of door jams can allow outside or attic air into the home if they are not properly sealed. So the first source of the dust in the home is usually that outside air getting in; things like sealing around the tops of door jams and putting gaskets behind light switch covers and outlets (All DIY projects) can help to reduce the dust coming into your humble abode.
The next and likely largest culprit for dust in our home is the duct system that all of our nicely conditioned air travels through. When the HVAC system is functioning and moving air through the ductwork, that air is moving at a whopping 8 MPH or so. While it is not moving that fast, it is moving quickly enough to create a Venturi effect at any openings that are in our ductwork. Wait, Venturi what? The Venturi effect is often used in water applications, you just need to remember that air and water behave in the exact same ways. You didn’t know you were going to be getting a physics lesson today, correct? I try my best not to complicate it and keep it in easy-to-understand terms so; The Venturi effect is similar to a small tornado being created outside of any opening in the duct system. The air traveling through the ductwork creates a vacuum and that air swirls like you would see in a tornado. These air currents then pull inside the ducts whatever was floating around the outside of the duct system. So, depending on where the ductwork is located in the home, you could be inadvertently pulling attic, crawlspace, or basement air directly into the domicile. Remember those filters you said you change often? Well if there are holes in the ductwork, that air being pulled in is bypassing the filter and getting blown out directly into your home.
If you have concerns about the air quality in your home, may I suggest that you give us a ring or shoot us an email and let one of our certified techs evaluate the entire air distribution system in your home. We can offer up multiple solutions for air quality improvement and shoo those dust bunnies away. Until I see you again the question is, Do you think that the rock band Kansas was right and that we are all just dust in the wind??