By Kurt Johnson, Immediate Past President, Maine Indoor Air Quality Council
We know there are things in our home that can make us sick.
According to the World Health Organization (WHO) and the National Cancer Institute, 80% of our cancers are caused environmentally. In addition, the EPA says that our #1 environmental threat is indoor air pollution. Now consider that the average American spends 90% of their time indoors, and you may want to start thinking hard about how to keep your family safe.
There are only 2 strategies to deal with indoor air pollution.
- Strategy #1 – Don’t bring pollutants in. This may seem simple, but the reality is otherwise. People themselves are a pollutant, and what people do generates pollution. And most, if not all, of the stuff we fill our homes with can be a pollution source, including the building materials making up the home itself.
- Strategy #2 – For pollutants that do get in, give them a way to get out. This is where ventilation becomes incredibly important.
How should we best ventilate?
The minimum ventilation standard most often applied in Maine (the ASHRAE 62.2 standard for acceptable indoor air quality) recommends ventilating the home enough to exhaust all the stale air and replace it with fresh air once every 3 hours. There are 2 big problems with how this is applied to many homes in Maine. First, natural leakage is unreliable. Sometimes the natural forces move enough air in and out of a home and sometimes they don’t. Wind and temperature are the driving force and both of these are changing on a daily if not hourly basis. The second is unpredictable distribution throughout the home. Unless the leaks are uniform throughout the home, some rooms get air exchange and some don’t. And it becomes very difficult to figure out which ones do and which ones don’t. And the tighter and more energy efficient we make our homes, the more likely it is that indoor pollutants may build up to the point where the people in them, you and your family, begin to get sick.
The same goes for running exhaust fans. You may get a reliable movement of air volume by running a fan, but the distribution throughout the house to where it is actually needed by you and your family is still a problem.
Neither of these methods—relying on natural air leaks or running exhaust fans—are energy efficient. Heat loss is 100% of the air leaving the home, and 100% of the incoming fresh air needs to be heated up to house temperature.
Balanced Ventilation with Heat Recovery is the Most Reliable Solution.
Fear not, there is a reliable solution and it’s called balanced ventilation with heat recovery. Some really smart people have determined that it makes more sense to control both the inbound fresh air and the outbound stale, polluted air. They know it is possible to control the rate and the distribution of air to each room, especially to those where people spend a lot of time, like our bedrooms.
They also know they can transfer heat energy from the air leaving the home to the fresh air entering the home. By running the 2 air streams through a heat exchanger core, it is possible to transfer 60 to 95% of the heat energy to the inbound air. This means that the fresh air gets pre-warmed, saving you money.
But more importantly, controlling the distribution throughout the house means you more effectively reduce indoor air pollution. This has the biggest potential to save money by reducing the threat of indoor air pollution and its health consequences. You see, lung cancer is the #1 cancer killer. Caused by what people breathe. And it costs between $40K and $200,000 every time some gets it. In addition to this, Maine has one of the highest rates of asthma in the country. Latest data (2009) asthma nationally costs over $56 billion annually. And these are just 2 examples of environmentally caused diseases. So the greatest potential savings of a well ventilated home is the health savings.
Build Right, Ventilate Right. These are words for us all to live by. As we move forward with our responsible and sustainable building practices, it just makes the most sense to also control our indoor air environment. First, be very conscientious about what stuff you bring into your home. Reduce as much as you can the sources of pollution in your home. And secondly, provide a reliable system to remove the ones that do get in. Controlled and balanced ventilation with heat recovery and distribution throughout your home.
Because a home should be a warm and safe place for your family.
The Maine Indoor Air Quality Council is a nonprofit organization dedicated to the creation of healthy, environmentally sustainable indoor environments. www.maineindoorair.org.
