Zero en­ergy house

Element - - Lifestyle - By So­phie Bond

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.”

“Why wouldn’t you build ev­ery house this way if you could?”

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 dou­bleglazed 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.

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