IAQ (Indoor Air Quality)

A few months back I attended a training class, sponsored by ASHI, on IAQ. There were some interesting facts on where the majority of your inside air comes from. Did you know up to 60% of your “breathable” inside air comes from your crawlspace? That’s over half of the air around me now that comes from under the house. That would make anyone wonder about the quality of air under their house. I am not selling anything, if this sounds like a sales pitch. I am just informing people of things they might not think about. Of course, everyone is aware of the possibility of Radon. Radon is a naturally occurring element discovered in the late 1800’s and early 1900’s and accredited to two different men. It hasn’t been until recently that Radon has been linked to cancers. So, radon is definitely on our minds. But, does anyone think about dew point? Dew Point, that thing the weather man gauges his muggy meter off of. The dew point is the saturation point of air. When humidity levels are high warm air can carry the moisture in a vapor. When that same air cools below the dew point, the moisture gathers to droplets, what we call condensate. These droplets are what we see on the grass in the mornings. The fact is, the dew point is everywhere. Vented crawlspaces have the same humidity level as the outside and even higher if no vapor barrier is in place. When the temperature in the crawlspace drops below the dew point, droplets form on surfaces. This is no different than the grass, or a better example the inside of a car windshield when windows are left down. It is the same in crawlspaces. HVAC duct leaks can cool the underside of your house below the dew point. When this happens, droplets form. They usually form around the cold areas first. (e.g. ductwork, transition boots, etc.) The concentration of condensation can cause mold, mildew and even rot, all of which we breathe without even knowing. Who would have thought that the dew point would affect your IAQ? Just breathe normally, but be aware of what we breathe.