Living walls not only help purify indoor air but they are also a striking design element in the home. Courtesy Furbish Co.
In this, the fifth and final article in our series outlining the standards for green building as presented by the US Green Building Council’s LEED for Homes and the National Association of Homebuilders Model Green Home Guidelines, we turn to indoor air quality.
At the beginning of this series, we said that green goals can conflict. In our article on energy usage in the home, we recommended home energy audits as a way of avoiding energy loss due to air leaking into and out of a home. If the sealing of a house is done without attending to ventilation, however, you get a “sick house”-one in which people cannot live safely and comfortably.
Many people suffer from various kinds of allergies and chemical sensitivities.For them, this question is particularly acute. Air sealing shuts out pollen and other problems, but it shuts in mold and off-gassed chemicals, which may be contained in building materials, carpet, furniture, and fabrics.
For most of us, outdoor air is much healthier than indoor air, even in the middle of a city. Reducing the number of fresh air exchanges in a given period, therefore, can be dangerous. The solution is to seal the house, but also to ventilate it in a controlled way at determined points, and heat or cool the air as it is brought in. This can be done through energy or heat recovery ventilators. More simply, whole house fans, operable windows, and bath and kitchen fans vented to the outside all help draw in fresh air as needed.
A technique that is becoming more common is to put the bath fans in often used areas of the house on humidistats, so that the fan will turn on automatically when humidity is high. Just ventilating bathrooms in this way can make a noticeable difference in air quality.
One place you do not want to draw air from is the garage. Check to be sure that the HVAC system does not run from garage to house in any way (e.g. the units are located in the garage) and that they do not share an unfinished wall. Also, a gas furnace or hot water heater should be vented to the outside with a closed duct system.
To improve indoor air quality consider an energy recovery ventilator, like this one by Broan.
Questionable materials, such as old floor tiles, can be inexpensively tested for asbestos, for example. Once that is done, new materials, which are pollutant-free, or nearly, can be introduced.
While you are doing any renovation project, don’t run the HVAC if you can avoid it, because gases released by materials used during construction can pollute your system. The use of MERV 8 or above filters, which can be changed after the project is done, is recommended. Installing walk-off mats during the work is a good idea as shoes bring in many indoor pollutants. The custom some people have of providing shoe storage at the front and back doors earns you a point in the NAHB system.
Volatile Organic Compounds (VOCs) are major contributors to indoor air quality problems. There are now many low or no VOC products available. Most major paint brands now have such a line and the paint performs well. The manufacturers websites usually have technical information. There are also lines of adhesives and sealants (glues and caulks) with low VOC. It is harder, but not impossible, to find carpet and other flooring with low VOC content.
American Clay makes clay paint using all natural ingredients.
American Clay and BioShield both manufacture gorgeous coatings using all natural ingredients like vegetable dyes. American Clay produces clay paint, which has to be troweled onto the wall, but has a hand-finished texture and an ability to absorb moisture and then release it into the air again when it is needed. The colors are mostly earth tones for clay paint, but it is possible to get natural nontoxic coatings in startlingly rich, vibrant colors.
You can earn LEED points and improve indoor air quality by using composite wood products (yes, that’s the kitchen cabinets) without added urea formaldehyde. There’s no doubt that formaldehyde is a poison that can contaminate air quality in the home, but until recently it has been virtually everywhere in cabinet lines. Probably the best known of the formaldehyde-free (and also otherwise green) cabinet manufacturers is Neil Kelly. They are on the West Coast, which means they leave a larger carbon footprint due to transportation of materials, but they do meet all the relevant guidelines. You may want to investigate others; more appear on the market every month.
Want to go further? Install a living wall, integrated into your ventilation system. The wall features plants that grow happily in a hydroponic system, which requires very little maintenance. Air is circulated through the wall, and the plants purify and humidify it. One living wall section can provide clear, comfortable air for a moderate sized home, as well as being a striking design feature.
Polly Bart is President of Greenbuilders, Inc., an eco-friendly builder and remodeler. For more information, visit greenbuilders.com or call 410-833-4814.
Resources:
American Clay: americanclay.com or 866-404-1634
Armstrong: armstrong.com or 717-397-0611
BioShield: bioshieldpaint.com or 800-621-2591
Broan-NuTone LLC: broan.com or 800-558-1711
Dayton Reliable Air Filter: reliablefilter.com or 800-699-0747
Furbish Company: furbishco.com or 443-874-7465
Home Decorators: homedecorators.com or 877-537-8539
Neil Kelly Cabinets: neilkellycabinets.com or 503-335-9207
Shaw: shawfloors.com or 800-441-7429
US Green Building Council: usgbc.org or 800-795-1747
