Monday, February 1st, 2016 by Ben Kershner
Air Quality is a major concern in many households. Allergens and pollutants such as Carbon Monoxide, pollens, dust and dust mites, formaldehyde, mold spores, pet dander, and more can build up in the air of your home and make you and your family sick.
So what can we do about it?
Step one: Control sources of moisture, because moisture breeds organic nastiness. All kinds of problems arise from excessive humidity. Try to keep the humidity in your home below 60%. I like to keep the relative humidity in my house right at 50%. Too much lower than that, and the dry air can be a irritant for some people. Too much higher than that, and you get the mold, mildew, dust mites, etc.
Here’s what you need to know: Warm air rises. Water and water vapor tend to move from areas of MORE moisture towards areas of LESS moisture (remember -- water moves from MORE to LESS) just as a dry sponge soaks up a wet puddle. The ground is often wet. If you have a dirt or gravel floor in your basement or crawl-space under the house, this is priority number one. Even if the soil seems dry, that’s likely because of evaporation. If all the water in the top foot or two of dirt has evaporated into your basement air, the ground will seem VERY dry. But all that water is now up inside your house providing the perfect environment for mold and mites. Stop the water and the water-vapor from getting inside, and dry the basement out. In the summertime, keep the warm humid air from getting in underneath your house. You don’t want that humidity under there. Read my article on wet basements, fix it, and move to step two.
Step one, (part 2) Before we move on, make sure your furnace and water heater are (still) properly venting their combustion fumes to the outdoors. For air-quality and safety purposes, this should probably be step 1, but it’s less common, so I’ve put it lower. Imagine for a moment that you’re lighting a fire in a traditional fireplace. You want the smoke from the fire to go up the chimney, and not billow back into the living room. Air from the living room goes up the chimney along with the smoke to help maintain “proper flue draft.” Your furnace and water-heater work the same way. Talk to a certified energy auditor and have them check you out. If the plastic caps on your water heater are melted, you KNOW you’ve got a problem.
Step two: Stop the drafts, because when warm meets cold, you get water. No really, it’s true when we’re talking about warm air hitting a cold surface. The air cools down below the dew-point and releases its vaporous moisture as liquid water condensation. If it’s summertime, you don’t want that hazy hot and humid air inside. It’s a source of moisture, and we want it OUT of our house. If it’s wintertime, we don’t want COLD outside air either! While you’re at it, take a look at your windows. If you get condensation on the inside of your windows, you probably also have mold at the base of your windows where the water runs down and soaks in.
Besides the humidity, drafts bring outdoor pollutants inside. As warm air in your house rises, it pulls dust and pollens in through the gaps and cracks, where it can become trapped in the fibers of your carpet. Fiberglass insulation is a great filter, trapping all kinds of fine particles as air passes through it. Look for dark filtration lines where the carpet meets the wall. If you have fiberglass in your basement rim joists, pull a piece out and look for the dark patches that indicate air-flow.
But what about pollutants that come from inside in the first place?
This is where the old adage, “A house needs to breathe” comes from. A house that is very tightly sealed can run into trouble with indoor air quality if appropriate steps were not taken. Let’s talk about mitigating these IAQ troublemakers.
Bathrooms are a big culprit. When you take a shower, all that humidity has to go somewhere. Hopefully, you have a properly vented bath fan that you actually USE. …and run for at least 20 minutes after the shower. This should take care of excess humidity. If the mirror is fogged, you’re still filling the room with humidity.
Volatile Organic Compounds, or VOCs are another problem in well-sealed houses. Paints and particle-board, cabinets and carpets, laminates and lounge-chairs, often contain formaldehyde or other chemicals that “off-gas” into the air where you can breathe them and get sick. Read the labeling on what you buy, and avoid VOCs as much as possible.
If your home feels “stuffy” in the winter, you may not have enough fresh air. Rather than opening up that window, look into an ERV or HRV – an Energy Recovery or Heat Recovery Ventilator. This is a fan that brings fresh air into your home, but runs it through a heat-exchanger first, so that it doesn’t blow icy cold winter air at you.
Lastly, a word should be said about carpets, curtains and cats, oh my! Logically, if you know what you’re allergic to, and you’ve invited it into your home, your HEPA vacuum cleaner and/or air-filter should be your best friend.