HOW HEALTHY IS THE AIR IN YOUR HOUSE?
by Michael Gotthelf
During the first half or so of the 20th century, when energy was relatively inexpensive and insulation and weather-proofing were relatively unknown, indoor air quality was not much of an issue. This is because the homes of that era naturally replaced air through cracks in windows and walls. Since mid century, homes have become increasingly tighter. The increasing popularity of foam insulation and more effective air sealing practices has increased this trend.
The building and energy codes over time have ever increasingly required that new homes and modifications to existing homes be constructed in a much more air tight manner. Poor indoor air quality can be an unintended consequence of current energy efficient construction if careful planning and consideration are not undertaken.
In a poorly built or maintained home, moisture and mold, carbon monoxide, VOC’s (Volatile Organic Compounds) can easily build up within the home to make the air less healthy than a smoggy day outside in a big city.
A home needs to breath. It needs to change out the stale air of breathing and living and also the build up of particulate matter and gases from all manner of sources within the home for fresh air. If a house was made too tight, it will require mechanical (or passive) ventilation to provide a healthy quality of air. There are many ways to do this. A fresh air makeup can be easily added to a HVAC system. For an additional cost, an Energy Recovery Ventilator can be added to capture some of the energy lost be expelling conditioned air to the exterior. (Note that before you invest in an ERV, though, there are other investments you may want to consider for a higher energy saving return on investment.) Remember to open your windows in the spring and fall and when the humidity and pollen count is not too high; the air outside is probably cleaner than the air inside.
To determine with some certainty whether your home requires mechanical ventilation, you may want to get a blower door test. A blower door test will tell you how tight your home is and can assist inform your remodeling decisions particularly related to the home’s energy efficiency. Think about getting a blower door test in conjunction with planning for a renovation.
For more information about blower door tests, see:
http://www.energysavers.gov/your_home/energy_audits/index.cfm/mytopic=11190
MOISTURE & MOLD
• The building code requires a bath fan or a window in each bathroom for good reason. Make sure each and every full bathroom has a bath fan, ducted to the exterior, not into the attic. Install fans with a timer to allow the fan to run long enough after a bath or shower to properly vent humidity from the room.
• You may not think of it, but top loading washing machines add a lot of humidity to the home. When it’s time to replace your washer, choose a front loading, energy and water efficient model instead of a top loading one.
• Make sure your gutters are properly sized, clean and your downspouts direct water away from the home. Ensure your property is graded to direct water away from your foundation. This will limit water infiltration into your basement.
• Ensure your crawl space has a proper vapor barrier on the floor or better yet, a slab. Crawl spaces need to be either insulated and conditioned or properly ventilated. Insist that your contractor get this right!
• We do not recommend wall vapor barriers, especially in an environment such as in Washington, D.C. In a cooling environment such as up North, where human activity in the home leads to a good deal of humidity, a vapor barrier is sometimes installed inside of the insulation.
• If you still have persistent humidity in your basement, set up a dehumidifier, hard piped to a drain.
VOLITILE ORGANIC COMPOUNDS
• Remember those FEMA trailers [http://www.msnbc.msn.com/id/14011193/] provided to victims of hurricane Katrina? The formaldehyde laden plywood and insulation which sickened so many people, is not much different from what’s used by many contractors without much thought. Though formaldehyde forms naturally in wood, it is also a component of glues used in plywood. Insist your contractor uses CDX (exterior grade pressed) plywood instead of OSB (oriented strand) for sub-floors since CDX contains less added formaldehyde. See: http://www.epa.gov/iaq/formalde.html
• Insist on low or no VOC paints and caulks from your contractor. Acrylic paint technology is improving by the year.
• Drywall is often glued as well as being fastened with screws. Many commercial drywall adhesives contain nasty chemicals such as xylene. Insist that your drywall contractor uses adhesives with low VOC’s.
• Choose water based wood floor finishes rather than oil based ones. There are several excellent low VOC products available.
• Choose kitchen cabinetry made from plywood (CDX) rather than particle board.
• Make sure that if you or your contractor uses fiberglass insulation for your renovation, it is the formaldehyde free type such as from John Manville.
GAS APPLIANCES
• Ensure your gas appliances (cook-tops, fireplaces, water heaters, dryers, furnaces, etc) are operating properly and are properly vented to the outside.
FIREPLACES
• That nice smell that emanates from the fireplace in winter is not really good for you. In addition to carbon monoxide and carbon dioxide, wood burning fireplaces can bring into your home unhealthy particulate matter in the form of smoke. http://www.epa.gov/woodstoves/healtheffects.html
ATTACHED GARAGES
• Attached garages contribute to poor indoor air quality throughout the home and are not recommended. Install an exhaust fan in your garage to duct carcinogens from your cars exhaust to the exterior; avoid parking your car in a garage or best of all, do not build a garage that is attached to your home.
DUST & CARPETING
• Avoid wall to wall carpeting. If you’ve ever lived with hardwood floors or tile you know how much dust you can sweep up in a week. If you’ve ever removed carpeting from a house, you may also know how much can collect in carpets, despite frequent vacuuming.
• Install a HEPA filter attached to your HVAC system or a media filter high MERV (Minimum Efficiency Reporting Value). Look for a filter with MERV rating of 10 or higher.
LEAD
Lead paint wasn’t completely phased out until 1978. Know that if you have house built before 1978 and especially one built before 1960, you can anticipate your home has some lead paint. For your safety and the safety of your children, ensure your painting contractor takes all necessary precaution when prepping and sanding old walls.
http://www.epa.gov/lead/
ASBESTOS
Asbestos is a naturally occurring compound, named by the ancient Greeks and used since antiquity for everything from fabric to more recently, shipbuilding, drywall compound, roofing and siding, insulation and floor tiles. It may come as some surprise that Asbestos was not banned in the US until 1989, though there was good scientific data going back decades and anecdotal evidence much further that asbestos is cancer causing. Asbestos is still used in the developing world.
The history of asbestos is emblematic of the glacial pace of change when money and big business are involved.
Many, many homes still have asbestos, most commonly as siding and basement floor tiles, but also pipe insulation. Before determining whether your asbestos should be removed, consult a professional. If asbestos is in a place which is not likely to be disturbed, in some cases it may be better to leave it. Products such as pipe insulation can be encapsulated as well as removed. Asbestos must be removed by a trained and qualified specialty abatement contractor.
http://en.wikipedia.org/wiki/Asbestos
http://www.epa.gov/iaq/asbestos.html
For more information about indoor air quality, visit the EPA website and World Health Organization website.
http://www.who.int/indoorair/en/
http://www.epa.gov/iaq/
Also we recommend the book Green Remodeling by David Johnston