Wainui Bay house most energy-efficient in NZ
"Little Greenie", the energy efficient house
Lawrence and Antje MacIntyre of Wainui Bay always reckoned they had built the most energy-efficient home in the country, and last week they were proved right.
Their “Little Greenie” eco-house, adjoining Abel Tasman National Park, scored a nine out of ten under the Home Energy Rating System, the highest-yet rating awarded in New Zealand by the Energy Efficiency Conservation Authority (EECA).
It proved quite a week for the MacIntyres. Professor Michael Donn from Victoria University’s Architectural Science Department in Wellington brought along three of his Honours students to study the house, and TV3’s Campbell Live show used the opportunity to film a piece that went to air last Thursday.
As well as accurately verifying the house’s insulation values, the students checked information from the home’s computerised data logger system, which is fed by nine probes and sensors around the house.
Said Professor Donn after the weekend: “We’ve been talking about building houses like this for years, but here finally we’ve got an owner who not only followed all the best high-tech principles, but installed a way of measuring it and is open to sharing that information. These factors all together make it an exciting project.”
EECA’s rating tool, which calculated how much heating and cooling energy is required for maintaining healthy and comfortable indoor temperatures in the dwelling, is based on representative typical climate data. In Little Greenie’s case, the annual heating demand is about 85 per cent lower than for an average new build constructed to code minimum requirements, and about 97 per cent lower than for an uninsulated house in the area. Solar panels provide all the power, with a small wood-fired furnace providing backup heating during long cloudy spells. Lawrence has allowed one cord of wood per for this, but the first cord is still unused. The house is almost entirely self-sufficient.
You can see why. From the subfloor right up to the roof, the 100 square metre corrugated-clad house is super-insulated. No concrete in the floor slab or foundations touches the ground; rather polystyrene has been used as a thermal layer. The home’s solar-heated water system not only supplies hot water to use, but pumps it around for underfloor heating. There are three layers of high density wool insulation in the walls and insulating interior adobe bricks. Similarly, the roof cavity is 300mm thick with wool batts.
The windows are thermally the best-performing argon-filled double-glazed available in New Zealand. The warmer-than-metal wooden window frames have clip-on aluminium facades to make them waterproof and keep them low-maintenance.
“It’s nice to experience the same temperature in every room instead of a hot spot in front of a fire and a freezing cold bedroom,” says Lawrence.
Other features include a compost toilet with an independent airflow to encourage warm bacterial action while controlling odour-less air movement within the house.
Lawrence, now 46, started his working career in the poultry industry, specialising in hatching and breeding, where he discovered he had a natural knack for working out temperature control systems. By 20, he was one of this country’s youngest farm advisors. His experiences since have included work as an Outward Bound instructor, setting up a fish smoking business, motorcycle trips across Africa and construction work in Africa, Papua New Guinea and Germany. It was on a 2003 trip to Germany to visit Antje’s family that he was inspired to adapt passive solar building in the ‘simple house’ or Bauhaus German philosophy to New Zealand conditions, building techniques and materials.
The EECA summed up Little Greenie like this: “It’s the best example yet of an international best-practice, highly energy-efficient and future-proof Kiwi home design that is already achievable using products and techniques which are readily available in New Zealand and do not need to cost an arm and a leg.”
Keen to share the innovative technology, the MacIntyres will be having an open day for Little Greenie on Queen’s Birthday Monday, 1 June, from 10am to 3pm. A ‘local couples special’ accommodation booking deal will be offered at $100 per week night.
A DVD of the Campbell Live piece is freely available to borrow through the i-site in Takaka, or you can get the Little Greenie story on <www.goldenbayhideaway.co.nz>.
Gerard Hindmarsh
