Indoor Air Quality
As homes are tightened up, the issue of indoor air quality comes front and center. Washington State has even developed a code for indoor air quality in new construction. It’s important! As we upgrade our homes to bring them closer to new construction efficiency levels, we need to be mindful of our indoor air quality.
Air Quality Problems and Solutions
Solutions to air quality problems depend on the source of the problem.
Some examples of indoor air problem sources:
Improperly functioning combustion appliances
Air from the crawl space under the house entering the living space
- People living in the house creating high moisture levels
General problem solutions in order of preference:
- Eliminate the source
- Block the source from entering
- Expel the pollutant after it gets in
Solutions to the above examples:
- Improperly functioning combustion appliances: Replace if it’s old and inefficient and in need of major repairs. Or repair broken combustion exhaust ducts
- Air from the crawl space under the house: Create an air seal between the crawl space under the house and the inside of the house. In some cases it can more effective and cost less to seal and insulate the foundation walls around the crawl space. This approach, referred to as "sealed crawls," can be very effective at reducing indoor air pollutants and has given remarkable relief to asthma sufferers and to people with chemical sensitivities.
- People living in the house: This is from cooking, showering, laundry, and just breathing. Expel via exhaust fans. Sometimes additional make up air needs to be added.
Signs of Poor IAQ or Inadequate Ventilation
It can be hard to know for sure, but there are a few indicators that should raise the question. Some manifestations can come from different sources. It’s not usually hard to sort it out what’s happening when you start to look more closely and do more testing to triangulate on the problem. And sometimes, we find home weaknesses that should be addressed for other reasons. Fix them and see what the collateral impact is. A good example is mold on a wall. Insulate the wall to prevent the condensation that is feeding the mold and the air quality improves.
Some signs of poor indoor air quality or inadequate ventilation include:
Condensation on windows
Mold on walls or the ceiling in the bathroom
Unfamiliar, unpleasant, persistent, or seasonal smells
The smell of dirt (while those gardeners among us find it attractive, it doesn’t belong in your house)
Visible buildup of dust and debris in the home, especially if you have heating ducts under your house
- Health issues that seem to flare up when you are in your home
What to do if you suspect an air quality problem
Find the source and eliminate it, block it, or expel it, in that order. More often than not, it really is that simple.
As part of our routine work in any home, we test air leakage to the outside. We want air exchange with the outside, but we want to understand the route that it takes so we can vet the passengers. A home leakage test helps identify the route. The test is called a blower door test because the device used is called a blower door. It’s just a big fan on your door that pulls air out of your house. We measure how hard it pulls, which indicates the leakage rate. (For more information on blower doors, look to Wikipedia). We also check combustion appliances to make sure they are not putting exhaust into your home, we check gas lines for leaks, and we check the relative humidity, which can also be a good indicator of exchange rate and air passage routes. Some homeowners have called on the American Lung Association for guidance and have even gotten counselors from ALA to pay them home visits.
Like all home performance improvements, it’s best to look at the upgrades in the context of the whole house. You don’t want to make a change that comes with unintended consequences or do something that will have to be undone later when addressing other issues. The one thing we strongly recommend not doing is adding air fresheners. Adding air fresheners - which, by the way, are unregulated because the manufacturers have successfully argued the contents are proprietary - is like adding flavoring to dirty water so you can drink it.