Because healthy heat is really vital
Home » Good Guide » Heating & Insulation » Heating & Insulation » Heat recovery and ventilationEven a warm home can be damp, so efficient ventilation is crucial
When I was a kid my mum installed PVC double-glazing so efficient I could feel the house depressurise when she opened the front door. At night she would close the place up tight and put the gas fire on. It was cosy, but I used to get a lot of headaches.
Since the leaky homes scandal some of us have been a little too eager to hermetically seal up our homes, just like my dear old ma. Weather-tight and insulated is good, but when your place is airtight it can cause problems.
The average household produces up to 30 litres of moisture per day. This comes from cooking, cleaning, drying clothes and other sources. It also includes about two litres created by each of us just breathing in and out. All this moisture gets absorbed into walls, furniture and other surfaces, until one day you find you can fingerpaint in the condensation on the windows, your dream home has begun to smell like an old sock, and mould and mildew have crept into your nooks and crannies.
Indoor air quality is also a concern rising rapidly up the environmental agenda, with the likes of Dr Michael Braungart, professor of engineering and the creator of the ‘cradle to cradle’ ecological design concept, leading the charge. He and others are placing a new focus on the way many modern materials in our paints, furnishings and electronic appliances ‘off-gas’ into our living space, with potentially harmful effects.
Home ventilation systems have become a common feature of homes in many parts of the world, and they are rapidly catching on here. An estimated 150,000 New Zealand homes have invested in home ventilation over the past five years. Half of these have installed the Heat Recovery Ventilation (HRV) system, which is made here and designed for the Kiwi climate and housing conditions.
HRV New Zealand has found an ingenious way to harness our pretty reliable Kiwi sunshine to tackle our weather’s wetter side. Traditional HRV systems extract air from the home and reintroduce air from outside, relying on a heat exchanger to hold on to some of the warmth.
HRV New Zealand systems take warm, dry air from the roof cavity where it has been heated by the sun beating on the tiles, filters it, and then circulates it through your home. According to the Energy Efficiency and Conservation Authority, the average New Zealand rooftop collects 220,000 thousand kWh of solar energy per year. That’s more than 20 to 30 times the home’s total energy needs.
Marcus Foot, HRV managing director, says: “While many people might initially view installing an HRV as a cost, many of our customers have reported their homes are not only healthier, but easier to heat, so are much more energy efficient. Our ultimate aim is to have HRV systems installed in all households as standard.”
According to the experts, there’s plenty to do. In 2005 the building industry’s watchdog and research organisation BRANZ found most Kiwi bathrooms relied solely on windows for ventilation. Only half of our kitchens vented moist air to the outside world, and 40 percent of timber-framed homes had poor or seriously inadequate subfloor ventilation.
Another BRANZ report highlights the advantages of active ventilation: it allows air to be supplied or removed at specific flow rates and at specific times, can cut down on heating bills because windows don’t need to be left open, polluted or moist air can be removed directly from where it is produced, and the removal of that air can be guaranteed. The report also mentions security: forgotten windows can be an open invitation.
A 2007 study funded by Health Research Council of New Zealand, the Ministry for the Environment and the Ministry of Transport found air pollution causes approximately 1,079 premature deaths, 1,544 extra cases of bronchitis and related illnesses and 703 extra hospital admissions for respiratory and cardiac illnesses in New Zealand every year.
“The statistics are alarming,” says Marcus. “All New Zealanders should be able to live in healthy homes.”
The company’s mission is also gaining offshore eco-plaudits. The HRV system was recently awarded the Good Environmental Choice Australia (GECA) mark—the first system of its type to achieve the GECA 08-2007 Environmentally Innovative Product standard.
“It highlights the integrity of our products and systems,” says Marcus. “While we cannot use the GECA mark on our New Zealand HRV product, it will reassure New Zealand consumers, as the products and business practices are the same. It also shows that New Zealand-developed products can lead the way in overseas markets.”
