Architecture and design: Zero energy house

Photo / Supplied

An Auckland couple are halfway through building the dream house; that is, ?one that doesn't cost them a cent in power bills.

At a glance it will look similar to many other suburban Auckland homes: three
bedroom, open-plan living, French doors onto a sunny deck. But for owners Jo
Woods and Shay Brazier the big difference will be the power bills - or lack
thereof.

This two storey home currently going up in Point Chevalier will be New Zealand's
first Zero Energy House. Careful design and the use of solar power and photovoltaic panels means that over the course of a year the building will generate as much energy as it needs to operate.

The pair of engineers - Jo is an associate at e Cubed Building workshop and Shay is head of design and innovation at SolarCity - are building the house not only for themselves but to prove to the general public and our politicians that the numbers do stack up.

"When you explain that it's zero energy and you're not worried about power price
rises it just makes sense. Why wouldn't you build every house this way if you
could?" says Shay.

"Every year the average Auckland home consumes 10,660 kilowatt hours from the grid and standard electricity prices are doubling every eight years."

The couple explain that design and insulation will reduce energy needs by 30 per
cent, solar hot water heating counts for another 25 per cent and the final 45 per cent in saving will come from photovoltaic panels. During winter Jo and Shay may need extra electricity from the grid but at other times they will be able to sell energy back into it, thus having a zero reading by the end of the year.

Jo says much of the house's energy saving ability comes down to simple passive
design.

"People tend to focus their build on a view when in actual fact sun is the most important thing. So we have large glazed areas on the north side and less on the south."

The glass is double-glazed and coated with a low E film which reflects heat back into the room. ?The concrete slab floor provides thermal mass, absorbing the sun's heat during the day and releasing it when the temperature drops.

"The overhang on the north side will keep it cool in summer. But in winter the lower level of the sun means it will heat most of the slab," says Jo.

Details like efficient lighting and low-flow shower heads will further reduce their energy needs. "And that technology is readily available but there is, perhaps, a lack of understanding about it," says Jo.

The home, designed with the help of A Design Studio architects, will also boast the country's first full integrated solar roof.

"On the north face we've taken the roof away and the panels are the roof," says Shay. ?The black panels - it will take 88 of them to cover the roof area - will hook onto the tile batten and are designed so that any tiler can easily install them.

He says photovoltaic prices have fallen dramatically in recent years, making the technology more accessible to the average consumer but he acknowledges some elements of the build are pricey.

"It's hard for people to assess why they should spend more up front but really it's simple maths and the savings will come. Electricity prices are only going up."

"It's really important that Zero Energy does become mainstream. A lot of how good our
health is comes down to our homes. There's a massive social benefit that could be achieved."

And it's not an impossible ideal by any means. In the UK zero energy will be the standard for all new homes by 2016.

They're now halfway through the build, the roof has just gone on and cladding has started. They hope to be living in their cosy new home by August.? Shay is designing a detailed monitoring system for the house which will allow anyone to go online and see exactly how much energy the house is creating and how much the occupants are using.

"It's great to say that we are zero-energy, but we've got to be able to prove it as well," says Shay.

www.zeroenergyhouse.co.nz