Passive houses on way

Energy-efficient "passive houses" - the first of which will be built in Arrowtown early next year - are coming to New Zealand, with a forum to be held next week in Wanaka.

Passive houses, structures which maintain indoor air temperatures above 18degC year-round without heating, originated in Germany in the early 1980s.

About 30,000 such buildings exist worldwide. They work by minimising heat loss and maximising passive heat gains using insulation, double-glazing, and airtight materials, together with a ventilation system.

Leading the information session will be Glenn Murdoch, director of Wanaka-based environmental architecture firm Vicus, and chairman of the Passive House Institute NZ.

Mr Murdoch, who on Wednesday night spoke in Queenstown, said New Zealanders spent an average of 90% of their time indoors, and often in conditions unsuitable for their health.

"We don't want to be building houses, work buildings and schools and creating unhealthy environments, so this is a initiative about changing how we build."

Mr Murdoch gave the example of a 200sq m passive house, which was estimated to use about $300 a year in heating, contrasting with "$300, $400, and even up to $1000 a month here".

"So you can't just look at it on capital payment; when you take mortgage repayments, maintenance and energy costs into it, we think a passive house will come out cheaper."

With Queenstown Lakes district homes reporting some of the country's highest power use and home-related sickness levels, he said it was appropriate Arrowtown would host one of the country's first passive houses.

Privately owned, the dwelling is due for completion early next year and will be open to the public for a limited time.

The free talk in Wanaka will take place in the Faulks Room, Lake Wanaka Centre, on Wednesday from 5.30pm.