SUS­TAIN­ABIL­ITY BUILT IN

The term ‘eco-home’ is, un­for­tu­nately, still as­so­ci­ated with wob­bly look­ing Hob­bit huts for rus­tic types at one end of the scale and plea­sure palaces for the rich and eco-guilty at the other. But more and more or­di­nary fam­ily homes are em­brac­ing the lates

Element - - Business - By Andy Ken­wor­thy

The new home of Stu Selby, Erika Whit­tome and their baby daugh­ter Rosanna is a great ex­am­ple. It was com­pleted in Fe­bru­ary on a tight, 350-square-me­ter sec­tion in Orakei, Auck­land, af­ter a six-month build. Its com­pact three-bed­room, two-story lay­out was de­signed by ar­chi­tect Frans Kamer­mans and con­structed by Har­ris Built Ltd, and is packed with a com­bi­na­tion of clever de­sign think­ing and cut­ting edge tech­nol­ogy.

First and fore­most, the home ap­plies ‘pas­sive so­lar’ de­sign to make the most of avail­able sun­light for free heat and light. It has large win­dows ori­en­tated north, with eaves that al­low in win­ter sun­light but re­strict the sum­mer sun to avoid over­heat­ing. There is a tiled con­crete floor on the ground floor and an in­su­lated block wall, both of which ab­sorb heat dur­ing the day to ra­di­ate that warmth back through the ex­tremely well-in­su­lated in­te­rior of the home as out­side tem­per­a­tures fall.

This is aug­mented with un­der­floor heat­ing, run­ning from a high-ef­fi­ciency heat pump, and low en­ergy LED light­ing. The mains elec­tric­ity sup­ply is sup­ple­mented with $14,000 worth of elec­tric­ity-pro­duc­ing pho­to­voltaic so­lar pan­els on the roof. A smart me­ter even al­lows the fam­ily to sell ad­di­tional power back to the grid when the pan­els are pro­duc­ing more than they need, con­tribut­ing to a pro­jected pay-back time on the sys­tem of just seven years.

Hot wa­ter is pro­vided by another heat pump, and rain­wa­ter is col­lected from the roof and stored in a tank un­der the deck, to be used in the toi­lets, gar­den, and wash­ing ma­chine. Around the rest of the home ev­ery other de­tail of sus­tain­able liv­ing has been con­sid­ered. The car­pets are pure wool, the wood used is all sourced from cer­ti­fied sus­tain­able sources, the taps are all low flow to re­duce wa­ter use and the wash­ing line is out­side un­der cover, to re­duce damp in the home and let the sun­shine do the work of a drier. A worm farm was even been in­stalled in the gar­den.

Stu said the fin­ished home is the re­sult of two years of in­spi­ra­tion and in­ves­ti­ga­tion, fol­lowed by a six-month plan­ning process prior to the build.

“We wanted to be as sus­tain­able as we could,” he said. “There needs to be a big push to build smarter, more en­ergy ef­fi­cient homes that you can heat more ef­fec­tively.”

The suc­cess of the de­sign has earned it seven out of ten stars un­der the Homes­tar home per­for­mance rat­ing scheme – when an av­er­age home in New Zealand would gain a max­i­mum of five. Homes­tar is a joint ven­ture part­ner­ship be­tween BRANZ and the New Zealand Green Build­ing Coun­cil. It also has the Min­istry of Busi­ness, In­no­va­tion and Em­ploy­ment, the en­ergy Ef­fi­ciency and Con­ser­va­tion Au­thor­ity and many of the big play­ers in the build­ing and

home de­sign in­dus­tries on board. As well as guide­lines on ma­te­ri­als and de­sign, the Homes­tar scheme pro­motes re­cy­cling dur­ing the build.

Stu says: “Go­ing through the Homes­tar rat­ing pro­vided a fo­cus. It wasn’t hard in terms of cost, but you have got to col­late all the ev­i­dence, and keep all your doc­u­ments and re­ceipts.”

The build cost came to around $3,500 per square me­tre, putting it at the top end of a con­ven­tional home build. How­ever, the fi­nan­cial pay-off comes in elec­tric­ity bills of just $60 a month, and the knowl­edge that the home should hold its value be­cause of the qual­ity of the ma­te­ri­als and the in­creas­ing pop­u­lar­ity of homes with sus­tain­abil­ity built in.

“I love the place, and ten years down the track it is still go­ing to look at­trac­tive, we are go­ing to have paid off our in­vest­ments and our en­ergy con­sump­tion is go­ing to be re­ally low.”

For more visit homes­tar.org.nz

Right: The dark tiled con­crete floor is an ef­fec­tive ‘sink’, sav­ing the sun’s heat un­til it is needed later on when the tem­per­a­ture drops. • The in­su­la­tion in this home is Pink Batts with ceil­ings rated R5. All re­main­ing ex­ter­nal/in­ter­nal walls and mid floor are R2.6. • So­larcity in­stalled the 2.3kWp ar­ray of so­lar pan­els. It is ex­pected to gen­er­ate in a typ­i­cal year 3100kWh/a, with a re­tail value of around $775, where no more than 150kWh are ex­ported to the na­tional grid per month.

Left: The so­lar ar­ray on the roof of this Orakei home is ex­pected to pro­duce around $775 worth of elec­tric­ity per year.

Pho­tos: Ted Baghurst

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