Healthy indoor air

When you're trying to create a sustainable new home or renovation then using building materials with low VOC is important.

While not currently regulated in houses, indoor air quality is another healthy home measure on the horizon. US architect Anthony Bernheim has specialised in designing buildings with better air quality and occupant health for the last 20 years.

He says that to create healthy buildings the "first and best thing you can do is take the pollutants out, then you do good ventilation, because obviously people breathe out carbon dioxide and that's a fact of life, so you have to ventilate."

Maximum limits

CSIRO estimates that occupants of new homes may be exposed to many times the maximum allowable limits of some indoor air pollutants. One of the contributors to poor indoor air quality is the use of synthetic building materials, finishes and furnishings which release outgas pollutants.

Some problem materials and sources to avoid include volatile organise compounds (VOCs), which are a range of chemical substances that become airborne, or volatile, at room temperature. They are given off by most paints, paint strippers, wood preservatives, aerosol sprays, glues, cleansers and disinfectants, moth repellents,air fresheners, stored fuels and automotive products, hobby supplies, and dry-cleaned clothing. James Hardie manufactured products contain no volatile organic compounds.

Biological pollutants including bacteria, moulds and mildew can form part of household "dust", and be respirable.

What's behind the walls

US architect Peter Pfeiffer says that it's "real problematic" not seeing what's going on behind a brick facade and is a fan of the water-sheeding capabilities of James Hardie products.

"Actually there's a neat little thing I can tell you about that," Pfeiffer explains. "Our second son had asthma, and the doctor suspected it was environmentally caused. Four months after moving into the new "fibre cement" house, his symptoms are all gone. And that's great."

Engineering and Architecture academic Dr John Straube also has pertinent comments on the moisture-resistant properties of James Hardie products.

"The cement-bonded wood fibres that make up the James Hardie product are quite resistant to long exposure to moisture for significant periods of time," he says. James Hardie test results for water permeability, rain durability and warm water immersion, support this.

Joseph Lstiburek is a principal of the Building Science Corporation and a key investigator for the US Department of Education Building America Program. He is acknowledged as a leading authority on rain damage, and mould and microbial contamination of buildings. Lstiburek agrees with Dr Straube and says that this is where fibre cement products "shine".

They allow "air circulation and don't inhibit drainage", he says.

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Is your home healthy?