What makes a healthy home?
Once at a building conference I heard about the results of a study on air quality. The study said the air quality inside the average new home in rural Wisconsin was 8 times worse than the air quality outdoors in New York City. This made my head swim. How could it be true? And then I heard more, and read more, about how toxins and pollutants can build up inside a home, and if there’s poor ventilation, reach unsafe levels in the air. Rates of asthma and other respiratory diseases have been on the rise in this country, and while industrial pollution is certainly a factor, the way houses are built and furnished is probably a bigger factor in the decline of respiratory health. How can a home be less toxic? Conceptually it’s very simple—reduce the nasty stuff inside and bring in plenty of fresh air. Practically, though, it’s not that easy. On the material side, builders have gotten away from good old-fashioned building materials like solid wood, plaster and stone, and for some good reasons: they’re expensive and poorly insulating. But when these materials are replaced with particle board, fiberglass, vinyl, and synthetic carpets, the home buyer is spending less money and probably using less energy for heating, but at the same time volatile organic compounds, formaldehyde, and other toxins have been introduced to the interior air. And in an effort to reduce energy use, builders have been trying to make buildings more air-tight and less drafty, thereby improving comfort as well as the utility bill. However, the combination of the tighter envelope and the off-gassing interior finishes is what leads to sick people in Wisconsin (and other places). With the advent of “sick building syndrome,” architects and builders are hopefully becoming more aware of what is being put in houses and taking steps to ventilate properly. It is now relatively easy to find out if a building material is air-quality friendly. Several ratings agencies exist to test and determine the safety of various materials; an architect can specify formaldehyde-free or low-voc plywood and paints; natural linoleum is available as an alternative to vinyl flooring; people should know better than to put carpeting in a damp basement, and so on. On the ventilation side, agencies such as the American Society of Heating, Refrigerating, and Air Conditioning Engineers studies indoor air quality and issues standards for rates of ventilation. They have formulas for determining how much air to bring into the house over time to ensure adequate fresh air supply. More specifically, in the homes GO Logic builds, we install a complete, ducted, mechanical ventilation system that delivers fresh air to bedrooms and living spaces and removes stale air from the kitchen and bathrooms. The incoming air passes through a heat-recovery unit that transfers almost all the heat from the outgoing air to the incoming air, which means there’s very little energy penalty for healthy ventilation. We determine the proper ventilation rate based on accepted standards. For example, in the 1500 square-foot model home, we will ventilate at a rate of 70 cubic feet of air per minute, continuously. This means the entire volume of air in the house will be changed once every 3 _ hours, ensuring healthy air quality for a family of 4 or 5. The air flow is very low and generally delivered to points in the house where it’s not noticed, so one never feels a draft. And on the material side, we specify only low- or no-voc materials and finishes. The floors are either polished concrete or solid wood; cabinets are formaldehyde-free. The building is incredibly air-tight, which helps tremendously in the energy-efficiency and comfort of the home, and when coupled with the ventilation system, results in a home that’s both super-efficient and healthy to be in. You can read more blog posts about the prototype GO Home here.
