Pas­sive­haus plays an ac­tive role in sav­ing money on en­ergy bills

This new build near Hud­der­s­field could be Bri­tain’s most en­ergy ef­fi­cient house. Sharon Dale re­ports.

Yorkshire Post - Property - - PROPERTY -

AF­TER shiv­er­ing our way through the cold­est win­ter in years, it’s hard to imag­ine how you could keep a home warm with just one ra­di­a­tor.

But that’s all Geoff and Kate Tun­stall have in their new three­bed de­tached... and they may never need to turn it on.

The cou­ple have just built what may be the most en­ergy ef­fi­cient house in Bri­tain.

Their an­nual heat­ing bill is pre­dicted to be just £75 a year, thanks to a pi­o­neer­ing build that com­bines Bri­tish ma­te­ri­als and con­struc­tion tech­niques with Ger­man technology.

The prop­erty, in Denby Dale, near Hud­der­s­field, took ten months to build and is the first An­gli­cised ver­sion of the Pas­sivhaus.

In­stead of com­pli­cated de­sign and ex­pen­sive bolt-on en­ergy gen­er­a­tors like wind tur­bines and ground source heat pumps, the Pas­sivhaus cre­ates a sim­ple “tea cosy” ef­fect to keep heat in.

It re­lies on clever de­sign, ori­en­ta­tion to­wards the sun, care­ful con­struc­tion and in­su­la­tion three-and-a half­times greater than re­quired by Govern­ment build­ing reg­u­la­tions.

No draughts can get in and no heat can leak out of the build­ing, but the air is never stale, thanks to a me­chan­i­cal heat re­cov­ery ven­ti­la­tion sys­tem that brings in fresh air from out­side, warm­ing it us­ing 99 per cent of the heat from the out­go­ing air.

The Green Build­ing Com­pany in Hud­der­s­field sug­gested the de­sign and built the house with the help of a Ger­man com­puter soft­ware pack­age to en­sure al­most com­plete air tight­ness and en­ergy ef­fi­ciency.

Project man­ager Bill Butcher says: “You can buy a prepack­aged Pas­sivhaus from Ger­many, but the ma­te­ri­als are com­pletely dif­fer­ent.

“They use solid wall pan­els and stick poly­styrene in­su­la­tion on the out­side of the house.

“They don’t fit into the lo­cal streetscape here, builders here aren’t fa­mil­iar with them and plan­ning can be an is­sue.

“This Pas­sivhaus is the first to be built us­ing Bri­tish con­struc­tion meth­ods with block­work, a cav­ity wall and stone cladding.

“We use the Pas­sivhaus method­ol­ogy but we have built in the English ver­nac­u­lar, which is a first. You can vary the de­sign as long as you ad­here to the prin­ci­ples.”

He adds: “What’s im­por­tant is de­tail­ing be­fore­hand and qual­ity con­trol on site. Ev­ery­thing has to be mon­i­tored from be­gin­ning to end to make sure there are no gaps, no leak­age or draughts.”

The three-bed­room prop­erty has been built in the gar­den of the Tun­stalls’ Vic­to­rian cot­tage and cost about £150,000

A Pas­sivhaus costs about 20 per cent more to con­struct than an av­er­age new-build but the Tun­stalls will en­joy a 90 per cent re­duc­tion in their fuel bills.

Warmth gen­er­ated from the sun through win­dows, body heat and cook­ing is usu­ally all that is needed to heat a Pas­sivhaus and the Tun­stalls have a so­lar panel to heat their wa­ter.

“There are 15,000 Pas­sivhauses in Ger­many and Aus­tria and we went to look at one af­ter Green Build­ing Com­pany rec­om­mended it.

“We were so im­pressed. They are or­di­nary, mod­est homes, noth­ing flash. It was mi­nus two de­grees out­side but the house we vis­ited was warm and healthy and com­fort­able to live in,” says Mr Tun­stall, a re­tired art and de­sign teacher

The idea is to max­imise heat gain and min­imise heat loss, so the York­shire Pas­sivhaus is highly in­su­lated and has triple glaz­ing with large win­dows on its south fac­ing front and small ones at the cold, north-fac­ing rear of the prop­erty.

Any gaps are min­imised dur­ing con­struc­tion and in­su­la­tion has to be con­tin­u­ous. Any ar­eas li­able to set­tle­ment cracks are sealed with spe­cial air tight­ness tape to pre­vent cold air seep­ing in. “The at­ten­tion to de­tail is in­cred­i­ble,” says Geoff.

“We haven’t got plug sock­ets on the out­side walls and we have no lights in the ceil­ing and that’s so the en­ve­lope and in­su­la­tion bar­rier isn’t punc­tured.”

He adds: “Fresh air isn’t a prob­lem be­cause of the ven­ti­la­tion unit and you can still open a win­dow. The only is­sue can be a dry at­mos­phere, which

They are or­di­nary, mod­est houses. It was mi­nus two out­side but the house was warm.

is why we used clay plas­ter on one wall in ev­ery room. This ab­sorbs mois­ture and then re­leases it.”

Bizarrely, the house won’t score top marks on the Govern­ment’s Code for Sus­tain­able Homes reg­is­ter be­cause points are awarded for re­new­ables like so­lar pan­els and wood­chip boil­ers. But it is be­ing closely mon­i­tored by the con­struc­tion in­dus­try. Both Mr and Mrs Tun­stall and the Green Build­ing Com­pany are hop­ing that the York­shire Pas­sivhaus will pro­vide a blue­print for the fu­ture of green house­build­ing in Bri­tain.

Bill Butcher says: "At the moment the Govern­ment places too much em­pha­sis on mi­cro­gen­er­a­tion, whereas Pas­sivhaus stan­dards fo­cus on the fab­ric of the build­ing. If you can re­duce your en­ergy use to just 10 per cent of the norm, then you don't need eco bling.”

He adds: “We’d wel­come the chance to build an­other Pas­sivhaus us­ing our in-house team and we are al­ready pass­ing on the knowl­edge we have gained with this project. It’s some­thing we think the vol­ume de­vel­op­ers are go­ing to have to take no­tice of.

“The main is­sue is chang­ing the build­ing cul­ture. We need to put more care into it and make sure we don’t sac­ri­fice qual­ity for short-term profit. We need to have round ta­ble sce­nar­ios where ar­chi­tects, clients and builders have a stake in the project, rather than putting out six ten­ders and us­ing sub contractors.”

He would also like to see Govern­ment in­cen­tives like those of­fered in Bel­gium, where Pas­sivhaus own­ers get a re­duc­tion in in­come tax and in Aus­tria, where they get grants of 15 per cent of the build cost.

The Tun­stalls mean­while are pre­par­ing to set­tle in and road test the new model.

“This win­ter will be the main test, but we’re con­fi­dent it will be warm enough. If it’s not we’ll have to have a party. Ev­ery per­son gen­er­ate a kilo­watt of heat,” says Geoff.

For more in­for­ma­tion on the Denby Dale Pas­sivhaus call Green Build­ing Com­pany, part of the Green Build­ing Store, on 01484 461705 or go to: www. green­build­ing­store.co.uk/denby dale­house

BUILT-IN SAV­INGS: The Pas­sivhaus cap­tures and re­tains heat from the sun for high en­ergy ef­fi­ciency. Geoff and Kate Tun­stall could have a heat­ing bill of just £75 per year.

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