Is a Tight Home a Sick Home?

June 20, 2018 hiadmin

By Phillip Beere–

Is an airtight house a health hazard? Some will say yes.

The EPA cites indoor air sometimes contains 2 to 5 times the pollutants compared to the outdoors, due to issues that range from moisture and mold to carbon monoxide poisoning and asthma. The source of these issues, include poor filtration, bad ventilation, homeowner behavior, and off-gassing from household products and finishes.

While the above may be true, there is a recent push by homebuilders to make indoor air quality (IAQ) healthier than outdoor air – even in cities with the highest levels of air pollution.

There is a growing trend toward homes becoming clean-air sanctuaries, and safe zones from high levels of outdoor air pollution; made possible with the help of improved building codes, increased awareness, designing for health, product innovations, and transparency.

(insert: graphic of most polluted cities)

The bare minimum: building codes

Building codes require minimum ventilation. Gary Church-Smith, IAQ Specialist from Panasonic Eco Solutions, says, “Codes are moving the baseline of minimum indoor air quality higher. ASHRAE 62.2 intends to help reduce or eliminate moisture, and improve IAQ through adequate fresh air.”

Max Sherman, senior scientist at the Lawrence Berkeley National Laboratory and ASHRAE board member says, “Tight construction is one of the most important cornerstones of high-performance homes, but is only possible with ensured dilution of indoor contaminants. And this ensured dilution is dependent on an effective base standard for whole-house and spot ventilation. This is why the ASHRAE 62.2 residential ventilation standard is critical to transforming the residential sector to high-performance homes.”

Moisture danger

Frank Najafi, principal of PropertyHealth, says moisture and mold become a problem when construction is too tight and ventilation is inadequate. Najafi’s firm specializes in IAQ assessment for commercial buildings, public offices, and universities. He says the main issue he sees in residential projects include mold and bacteria due to water leaks, trapped moisture, lack of ventilation and filtration, and occupants sealing up windows in an effort to save energy.

(insert: graphic of experts IAQ)

For new home construction, he emphasizes the importance of installing a weep screed, a type of building material used along the base of an exterior stucco wall. The screed serves as a vent so that the moisture can escape the stucco wall finish just above the foundation.

Off-gassing: For new homes, Najafi says formaldehyde is the number one risk to IAQ, including the off-gassing of cabinets, wood furniture, paints, and hardwood flooring and finish. “Even with a properly designed mechanical and ventilation system, the off-gassing from these items will still circulate.”

Testing IAQ: In order to assess air quality and potential issues, Najafi implements SUMMA canister testing and TO-15 analysis. The advances in sampling for volatile organic compounds have made it simple and more effective than in the past. No longer is the investigator worried about calibrating their pumps and finding a power source.

Beware of toxic materials

Bob Krell, publisher of Healthy Indoors Magazine, says, “You can do everything right; seal the home, install perfectly designed ventilation and filtration systems, but still have toxic indoor air if the wrong materials are used.”

“You can do everything right; seal the home, install perfectly designed ventilation and filtration systems, but still have toxic indoor air if the wrong materials are used.” 

Krell says homebuyers now rank health as more important than energy efficiency, but most builders have yet to catch up to this trend. Homeowner interest in healthy indoor air is reflected in an increase in Healthy Home Evaluator certifications from the Building Performance Institute (BPI). BPI develops the technical standards for home energy audits and for energy efficiency, health, and safety improvements.

How do we know what is in a building product or finish? Krell says product transparency is the future of green building. This is consistent with the message from the American Institute of Architects, advising architects to ask, does a manufacturer promote transparency and disclose ingredients?

Read the full article in the May 2018 issue of Healthy Indoors Magazine at:

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