The Ultimate Green Home: Air

Greening your home can make it healthier, cheaper and more comfortable. Photo / Supplied

Your home can be transformed into a lean, mean machine, making its own power, collecting and storing water, producing no waste and, most importantly, keeping you healthy. Here’s how - in a four-part series.

Air quality in New Zealand homes is generally poor, with high rates of asthma and respiratory conditions. Despite our temperate climate, the average indoor temperature is two degrees lower than the 18 degrees recommended by the World Health Organisation. The average human breathes 11,000 litres of air each day, with up to 90 per cent of that indoors.

Moisture

Humidity in the average insulated home is between 65 per cent - 80 per cent, with un-insulated homes over 75 per cent. A damp, cold home is the perfect breeding ground for black mould (stachybotrys), and a warm, moist home will harbour dust mites, which to survive must absorb water from the air. A healthy home should have a humidity level of between 30 per cent and 50 per cent.

Use of low VOC (volatile organic compounds) paints and varnishes:

Off-gassing occurs for most materials, and increases as the temperature does. The most common gas is formaldehyde - a toxin incorporated into a huge number of products. Decreasing the levels of potentially toxic gases is best achieved by using natural materials - such as timber or wool - wherever possible.

Carpets can harbour dust mites and are often the cause of allergies. Wool carpets perform best, but carpet-free floors are best.

Avoid LOSP (light organic solvent based preservative) treated timber as it emits VOC's. Waterborne preservative treatments such as boron are the best option.

Use low formaldehyde 'E0' engineered wood products or glues with no formaldehyde added such as Purbond.

Ventilation and filter systems

Super-efficient to run, the systems that bring in fresh outside air, filter it and push it into your home also serve to drive out moisture and lower the humidity. The latest models use heat exchangers to warm the air coming into your home by using the latent heat of the moist air you're getting rid of.

It's important to properly vent areas in which moisture are created - such as kitchens, laundry and bathrooms. In the kitchen and bathroom, an effective rangehood and ventilation system (check out the Schweigen range for silent operation) will suffice, and in the laundry be sure to vent a clothes dryer directly outside.

Auckland architect Tony Watkins argues that there is no place for a bathroom inside a house, but for most of us that isn't a reality, so fans, open windows and simple products such as a Showerdome are very effective.

Rising damp

Moisture barriers under your home are recommended for homes whose floorboards sit less than half a metre from the ground, or are not well ventilated.

Gas heaters without a flue

These heaters are a recipe for a damp home - the byproducts of their combustion is water vapour, carbon monoxide and carbon dioxide. Replace with a healthy option.

Check out more tips:

• The Ultimate Green Home: Water
• The Ultimate Green Home: Energy
• The Ultimate Green Home: Waste

Further reading: A Deeper Shade of Green, edited by Johann Bernhardt, is a seminal work in green building and living. To get a copy contact the publisher aaltobooks.co.nz or to email aaltobooks@xtra.co.nz.

If you'd like to learn how to make your building or renovation project more eco-friendly, you can book a free two-hour consultation with a specialist eco design advisor through Auckland Council. To book a meeting or to arrange a presentation at an event, call 0508 326 337 or email Eion Scott on eion.scott@aucklandcouncil.govt.nz.