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The IAQ challenge

Mitigating harmful chemicals in tightly constructed homes

The auto industry has more than a few things in common with the building industry these days. The main thing is the movement in both industries toward making incredibly efficient products. With houses, builders are trying to build the tightest building envelopes possible to make houses that are extremely energy efficient. With automobiles, car manufacturers are trying to build cars that get the most miles per gallon. The Toyota Prius is currently one of the top-selling cars in the U.S., which is widely credited to its nearly 50 miles per gallon fuel rating. But there is one thing many car owners don’t know about the Prius. While the great fuel efficiency helps improve outdoor air quality, the Prius itself has less than par indoor air quality. In a recent study, more than 60 volatile chemicals were found in the cab of a newly purchased Prius. Most of the chemicals are believed to come from off-gassing plastics, fabrics, wire sheathing and floor coverings. This is also a problem that plagues many new, tightly built, energy-efficient homes.

 

That new home smell

The tighter the building envelope, the better a customer’s home will retain heat in the winter and trap in cool air during the summer. But the problem with having such a tight building envelope on a new house is escaping that new house smell. The smell is actually caused by a number or different toxic and hazardous gases being emitted from different sealants, adhesives, floor coverings and fabrics that are often used in building new homes. These materials and products will off-gas for quite some time, and due to the home’s airtight qualities, the gases cannot escape the home and have nowhere to go except into the lungs of the homeowners, causing different allergies—and, some doctors say, cancers. Situations like this are the reason recent studies have shown that indoor air quality can be up to five times worse than outdoor air quality.  

Not only do tight building envelopes keep in harmful off-gases often caused by paint and carpets, but the lack of fresh air in the home also provides a safe haven for mold, bacteria, viruses, dust mites, pet dander and other allergy-causing substances.

Lessen VOC impact

Common toxins in the homes are introduced through the use of paints and adhesives that contain volatile organic compounds. A common VOC is formaldehyde, which is often added to particleboard, plywood and fiberboard.

“Formaldehyde is probably one of the nastiest VOCs,” said Rebecca Morley, executive director of the National Center for Healthy Housing, a nonprofit that focuses on research, policy, and training professionals in the public and private sectors. Formaldehyde off-gassing is slower than other VOCs and may continue to seep into the home long after the smell of paints and other sealants has gone away.

One easy way to improve indoor air quality is to urge clients to use formaldehyde-free wood. The American National Standards Institute has set levels for the amount of formaldehyde that can be included in medium-density fiberboard. The levels vary according to whether the boards will be used for the interior or exterior of a new home.   

Other major contributors to levels of VOCs in a home are paints, adhesives and carpets. The organization Green Seal has set standards for the levels of VOCs that can be added to paints and adhesives while still earning a Green rating. Zero-VOC products are also on the market.

For carpet, the Carpet and Rug Institute has a Green Label Plus endorsement for low- to zero-VOC carpets, which help improve indoor air quality. Another good model to go by, according to Morley, is to keep carpet out of any area of the home where moisture builds up. This will prevent mold from growing under the carpet.

“I think there is a trend in using these products,
so the price should come down quickly,” Morley said.

Fresh air: In and out

“Even with low-VOC products, indoor air quality is still a major issue, especially in residential homes,” said Adam Schuster, manager of products and marketing for Rheem. “One-third of Americans suffer from allergies that can be helped out with improved indoor air quality.”

Local exhaust fans are another way to improve indoor air quality. According to Morley, two of the best places to install these fans are the bathroom, to cut down on mold spores, and in the kitchen, to pull out harmful contaminants and exhaust. The exhaust fans must not spill into attic space; they must filter the stale, contaminated air out of the house.

“Highly energy-efficient homes need to balance the fresh air,” Morley said. “Mechanical ventilation is needed in these tighter homes.”

Heat and energy recovery ventilators, according to Morley, are a great way for a home to introduce fresh air into the mix without compromising energy efficiency. The HRVs work by expelling from the home stale air that may contain a number of contaminants, and then filtering in and heating new fresh air. ERVs transfer heat and moisture.

The EPA has even started qualifying homes for its Indoor airPLUS program, set to go hand-in-hand with its Energy Star program, which is aimed at protecting homeowners “against indoor air pollutants such as gases, chemicals, pests, carbon monoxide, radon and mold.”

Nature’s harmful gases

According to Morley, more people die from cancers related to radon, usually lung cancer, each year than die in drunken-driving accidents. Radon is colorless, odorless, tasteless, naturally occurring gas that can accumulate in homes. The gas seeps into homes through the slab foundation, and in airtight homes it continues to build up. The EPA has a map on its website to show people if they live in an area with a high concentration of radon.

There are two ways to keep homes clear of radon: passive and active radon mitigation. Passive mitigation is carried out by drilling a hole in the slab foundation of the house and installing a pipe, which pulls radon out of the ground and out of the home using the stack effect. Active mitigation includes installing a fan at the top of the pipe to pull radon out of the home more aggressively.

Another colorless, odorless and tasteless gas, which can seriously affect indoor air quality and surely cause death when found in high levels, is carbon monoxide; often called the silent killer.

“In homes with tight building envelopes, there should be CO alarms on every floor outside of bedrooms,” Morley said.

Carbon monoxide can be cut down by using sealed combustion units for water heaters and furnaces; by pulling fresh air from the outside to cause combustion, these units prevent back-drafting and the buildup of carbon monoxide.

“Builders that are forward-thinking and ready to provide options for those that are interested in saving money on energy and value health will begin to crowd out the others which aren’t making this type of thinking a priority,” Morley said. “Studies are showing women are taking on more of a role in buying or building homes, and they put families’ health as a top concern.”

Morley knows that not one option will provide a magic cure to provide the best indoor air quality.

“There is a growing need to think in more of an integrated fashion—you can’t just focus on one thing,” Morley said. “If you only focus on saving energy you’re not thinking about indoor air quality. We need to think about all of these things from multiple directions.”

Read the original byDaniel Savickas, BNMag.
The IAQ challenge

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