Passive house plus issue 9 (UK edition)

editors letter

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ABC Certified Average Net Circulation of 9,621for the period 01/01/13 to 30/06/13

Issue 9

PUBLISHERS: Temple Media Ltd.PO Box 9688, Blackrock, Co. Dublin, IrelandT: +353 (0)1 2107513 / +353 (0)1 2107512

Email: [email protected]

EDITORIALEDITOR: Jeff ColleyE: [email protected]

DEPUTY EDITOR:Lenny AntonelliE: [email protected]

REPORTER:John HearneE: [email protected]

REPORTER:Kate de Selincourt

CONTRIBUTORSDr Benjamin Krick, Passive House Institute

Tom Dollard, Pollard Thomas EdwardsChris Parsons, Parsons + Whittley Architects

Paul McNally, PassivHaus Architecture Company

UK SALESStephen MolyneuxE: [email protected]

READER RESPONSE/ ITDudley ColleyE: [email protected]

ACCOUNTSOisin HartE: [email protected]

ART DIRECTORLauren ColleyE: [email protected]

PRINTING: GPS Colour Graphics, T: 028 9070 2020

www.gpscolour.co.uk

Publishers circulation statement: Passive HousePlus (UK edition) has a print run of 11,000 copies.10,000 copies are posted to architects, clients, con-tractors & engineers. This includes the membersof the Passivhaus Trust, the AECB & the GreenRegister of Construction Professionals, as well asthousands of key specifiers involved in current &forthcoming sustainable building projects

Disclaimer: The opinions expressed in PassiveHouse Plus are those of the authors and do notnecessarily reflect the views of the publishers.

Cover: River Studio EnerphitPhotograph: Marco da Cruz

he old management adage you cant manage what you dont measure is fundamentalto low energy building. After all, whats the point of our industry spending time, effortand money on making supposedly low energy buildings if we dont check how theyreactually performing. Is it because we wont like what we discover?

Looking at Ireland and the UKs energy standards for new buildings, Ireland appears to take theview that its best to aim high (in the case of dwellings at least) but not monitor how the resultantbuildings are actually performing, while the UK is instead aiming much lower but is actuallymonitoring performance. Really, given how high the stakes are in terms of climate change, energysupply and the needless running costs and discomfort of sub-standard buildings, we need to beaiming to design and build ultra low energy buildings, and we need to monitor those buildings or representative samples of those buildings to see whether the approaches we try out actuallywork or not, and to feed that information back into how we legislate, design and build.

Calculated and actual performance can differ wildly, for a variety of reasons, and we shouldntassume that buildings with energy performance calculated to comply with building regulationswill actually perform to those levels. Sadly we have no reason to expect this to be the case. Forits part the Westminster government recognises that a significant performance gap exists betweendesigned and actual energy use of notionally low energy buildings in the UK, and although itsregulations are much worse than Irelands on paper, the government has pledged to eliminate theperformance gap in England, stating that by 2020 90% of all new homes will perform as well asor better than designed, with substantial and detailed analysis ongoing at present by the ZeroCarbon Hub to establish the causes of this gap. The Irish government appears not to share theseconcerns. There hasnt been an attempt since 2005s still unpublished Energy Performance Surveyof Irish Housing to check whether the actual energy performance of new build homes corresponded tothe calculations. A cynic might argue that the widespread non-compliance with building regulations and, perhaps unsurprisingly, correspondingly higher than expected energy usage noted in thatstudy, serves a powerful disincentive for the authorities to commission further research.

And while to an extent poor performance may be down to non-compliance with regulations, there arebroader questions about some of the assumptions made in the regulations and more particularlyin the associated documents. I contend that its possible to satisfy Irelands technical guidancedocuments or the UKs approved documents and therefore show prima facie compliance withthe regulations and still produce a building that fails. Some of the natural ventilation strategiesthat abound, coupled with ropey thermal bridging and airtightness performance are causes forparticular concern.

So its critical that we dont just take a tick box approach to compliance, but actually design andconstruct buildings that work buildings underpinned with a sound theoretical basis and strongempirical evidence of actual performance. Part of the reason my company rebranded our magazinefrom Construct Ireland to Passive House Plus was because of our conviction that the passive housestandard offers a tried and tested route to delivering ultra low energy, healthy, robust buildings. Werenot saying that everyone should build a passive house, but we think we all have a lot to learn fromthe principles and rigorous attention to both a priori and empirical data which underpin its approach.

Regards,the editor

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6 NEWS

14 BUILDING OR UPGRADING?Passive House Plus is here to make your building more sustainable

16 COMMENT

18 INTERNATIONALThis issues selection features ultra low energy buildings from Mexico,Germany, New Zealand and Italy, and illustrates how widely the energy efficiency specification can vary in different climate zones.

28 NEW BUILD28 Passive fishermens cottages on Norfolk coast

Three award-winning, affordable homes in scenic North Norfolkhave achieved passive certification while embracing a uniquelocal style of architecture.

34 Ledbury passive house embraces warmth, wood & lightFor Ruth Busbridge and her builder Mike Whitfield, aiming forthe passive house standard was just one part of an environmentallyconscious approach that put natural, healthy materials to the fore.

40 Sleek-and-striking passive house graces eco-villageThe eco-village at Cloughjordan, Co Tipperary, is no strangerto low energy buildings, and with this passive house, architectPaul McNally set out to prove that energy efficiency and goodarchitecture go hand-in-hand.

44 Low energy Tipperary offices go for goldA new development in Tipperary aimed to combine excellentlevels of airtightness and insulation with generous glazing andnatural ventilation, to deliver ultra-modern, comfortable, lowenergy offices. How did it work out?

50 UPGRADE50 From drab farm shed to passive, light-filled studio

When Sjlander da Cruz Architects sought to turn an old abestos-clad shed into the firms new studio, it offered the perfect opportunityto put an enthusiasm for passive house design into practice.

58 How to rescue a 1970s bungalowA passive retrofit in Co Meath offers a template that could beapplied across much of the Irish housing stock: a long, dark,1970s bungalow was transformed into a bright modern homethats now warm and comfortable.

62 INSIGHT62 The new proposed passive house classes explained

The Passive House Institutes announcement of new classes ofpassive house certification including renewable energy generation at this years International Passive House Conference causedsomething of a stir. Dr Benjamin Krick, the institutes head ofcomponent certification sheds some light on the new classesand explains the rationale behind proposals which may set uppassive house for a fabric first approach to near and sub zeroenergy building.

66 Will building boom see low energy failures?Low energy building isnt complicated, but its easy to get wrong.Since Irish house builders downed tools en masse when thelast boom ended, energy efficiency standards for new homeshave seen unprecedented rises of 40% in 2008 and 60% in 2011,shooting far ahead of the UK. But with signs of a new boomemerging, can the industry get to grips with this brave new worldof insulation, airtightness and thermal bridging and deliverhealthy low-energy homes or are damp and mould set tobecome the norm in new build?

70 SUBSCRIBE FOR CHRISTMAS!Its the Christmas gift that keeps on giving! Treat yourself, your colleague, ornearest & dearest to a subscription to Passive House Plus for just 20.

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News

NZEB focus at UK Passivhaus Conference

The 2014 UK Passivhaus Conference washeld in Stevenage on 16 October, and centralto discussions were EU targets for near zeroenergy buildings and how these relate to passivehouse.

By 2021, all new buildings in the EU will haveto be nearly zero energy buildings (NZEBs),though each country will come up with its owndefinition of this term. Speaking at the conference,Jessica Grove Smith of the Passive HouseInstitute said: A passive house is definitely anear zero energy building, but not all nearzero energy buildings are passive houses. Ofcourse, we think they should all be. NZEBswill have to generate some renewable energy,and partly with an eye to this, the PassiveHouse Institute has introduced new certificationcategories Passive House Plus and PassiveHouse Premium that reward renewables.(The new categories and the rationale behindthem are explained in an article by the PassiveHouse Institutes Dr Benjamin Krick on pp62-65.)

The requirements of the UKs 2016 national zerocarbon standard, which the UK governmentsays will meet its NZEB obligations, will likelylag well behind passive house. NeverthelessDavid Adams, the director of the Zero CarbonHub (set up to advise the government on thestandard) asked those attending to defendthe hubs recommendations (based around afabric standard of around 40 to 45kWh/m2/yr,depending on building form), for fear these wouldbe further diluted by industry. He pointed out

that crucially, a requirement for as-built per-formance had been introduced to help tacklethe performance gap.

Meanwhile Sebastian Moreno-Vacca of Brussels-based architects A2M told the conference abouthow, in 2011, the Belgian capital legislated thatall new buildings must meet the passive housestandard from 2015. We legislated first anddiscussed afterwards, he said.

Some prominent passive house clients at theconference emphasised that comfort, healthand fuel poverty relief rather than carbon were their reasons for procuring passivebuildings. Emma Osmundsen, housing managerat Exeter City Council, said: We are focusedon addressing need, for those in greatest need.We are aiming to lift people right out of fuelpoverty. And we want the buildings to behealthy.

It was notable at the conference that passivehouse is no longer seen as an extravagance not least because in some instances, it hasbeen the money-saving option that has alloweda cash-constrained scheme to go ahead. Atthe Hereford Archives & Records Centre, asArchitypes Mark Barry reported, the originalbrief was for a building built to the BREEAMVery Good standard, but the budget was cutand it looked like the building would not goahead. We offered to do passive house at a4.5% capital saving and much lower runningcosts, and the project became viable for the

client and went ahead, Barry reported.

Other projects that had to include renewablesto meet various sustainability specificationsmade valuable savings by designing to thepassive house standard, enabling the outlayon renewables to be reduced or even elimi-nated. The conference also heard that the in-creased asset value of passive buildings isbeing formally recognised now, with Jon Lefeverof Hastoe Housing Association reporting thathe had received a valuation for some homesunder construction that added 10,000 perunit based on their passive house certification.

From a purely commercial point of view, theconference also heard that landlords arejudging that building to passive house givesthem the theoretical option of charging higherrents, important when raising finance. Finally,the conference also heard that while post-oc-cupancy surveys have revealed occupants ofnew passive dwellings are delighted with theirhomes, there have a been a few reports ofoverheating. But Martin Ingham of LinktreatLtd said it was principally householders whohad yet to fully grasp how to manage theirhomes for cooling who reported discomfort.(Report by Kate de Selincourt. A longer versionof this article is online at www.passive.ie).

(above) Speakers at the 2014 UK Passivhaus Conferenceincluded the Passive House Institutes Jessica Grove-Smith, Zero Carbon Hub director David Adams andExeter City Council housing manager Emma Osmundsen

Corrections In the article How to save social housing blocks in issue eight, we wrongly quoted David Williams of Eastlands Homes as saying: The residentsin the maisonettes are the poorest people in our housing stock. This was a misquote. His actual words were, the maisonettes are the poorestin our housing stock, and the quote was from an article in Inside Housing magazine, who we should have credited.

In the same issue, we wrongly attributed photography for the Riedberg school, youth centre & gym in our International Selection featureto Achim Groe. The photographs were in fact by Thomas Herrmann. We apologise for these errors.

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News

Passive House Institute announces ComponentAward & wins refurb award

The Passive House Institute has announcedthe launch of its second annual ComponentAward, which honours the best passive housecertified windows. This year the award willparticularly reward windows that are suitablefor step-by-step retrofit projects, where theremight be significant time gaps between differentelements of the renovation.

According to a statement from the institute:This time the focus will be on windows whichprovide good results both during the transitionalperiod without faade insulation as well as aftercompletion of the refurbishment. The winnerswill be announced at the International PassiveHouse Conference, which will be held from17 - 18 April 2015 in Leipzig.

The Component Award 2015 will primarily as-sess the cost efficiency of passive house windowswithin the context of building refurbishment;in doing so, the purchase costs will be measured

against the potential savings, the statement con-tinued. The competition jury will also consider theaspects of practicability, innovation and aesthetics.

Categories for the award include wood, wood/aluminium, aluminium and PVC, and any windowcertified by the Passive House Institute is eligibleto enter. The deadline for submissions is 1 February2015, and further details can be found onlineat www.passiv.de/en/component-award

Meanwhile the institute has been rewarded bythe Refurbishment Road Map competition, heldby the Institute for Energy and EnvironmentalResearch in Heidelberg, for a concept designedto encourage a high quality approach to step-by-step retrofits which may be carried outover a long period of time through the prepa-ration of a comprehensive renovation plan be-fore the first work is undertaken.

A statement from the institute read: According

to this concept, the individual modernisationsteps are input into a new version of the PHPPwhich has been optimised for this purpose.Certification can take place if the overall planhas been reviewed by a certifier accreditedby the Passive House Institute and if the firstmeasures have already been implemented;this confirms that the Enerphit standard for re-furbishments will be achieved upon completionof the road map. This analysis is thus a pre-cursor to the actual certification of the buildingwhich may only be completed years later.

A detailed description of the project can be foundonline at europhit.eu/certification-retrofit-plans

(above) Prof Wolfgang Feist (right) and Dr BenjaminKrick (left) of the Passive House Institute meet rep-resentatives from M Sora, one of last years ComponentAward winners; An illustration of the Passive HouseInstitutes step-by-step refurbishment concept

The UK branch of cellulose insulation manu-facturer CIUR, and PYC Insulation Ltd, haveannounced a new commercial partnership aimedat developing and distributing Warmcel celluloseinsulation in the UK and Ireland.

Excel Industries Ltd, the previous manufacturersof Warmcel, went into administration earlier thisyear. CIUR subsequently purchased manu-facturing equipment and branding rights toenable it to continue manufacturing Warmcel.

Michal Urbanek, managing director of CIUR UKsparent company CIUR AS, said: Since CIURAS acquired the Warmcel brand and manu-facturing plant from Excel Industries Limited,we wanted to set up a strong team in order tocontinue to develop and support the sales ofWarmcel cellulose insulation in the UK. In ad-dition to our excellent manufacturing processand UK technical and commercial team, by

partnering with PYC Insulation we can nowoffer a much broader package of support toWarmcel installers and work more effectivelywith architects, specifiers and developers.

Meanwhile, Jasper Meade, MD of PYC Insulation

Ltd, said: After many years of being the largestWarmcel installer in the UK, PYC has restructuredand expanded its business. This means thatrather than focussing on installing Warmcel,we are now providing technical and commercialdevelopment assistance for other Warmcelinstallers. This involves using our experienceand long term relationships with architects,specifiers and developers to grow the marketfor Warmcel, as well as support with machinesand building systems with Warmcel. In order toachieve our goals we needed to find a cellulosemanufacturer, with an excellent cellulose fibreproduct and commercial and technical team.In CIUR we have more than achieved this goal.The continuation of the Warmcel brand in the UKand the formation of our new partnership with CIURis excellent news for the UK construction sector.

(above) Warmcel insulation will now be available inthe UK and Ireland via PYC in partnership with CIUR

PYC Insulation and CIUR announce Warmcel partnership

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News

Genvex units bring heat, fresh air & hot waterto award-winning schemeThe Burnham Overy Staithe development in NorthNorfolk picked up a prestigious UK PassivhausAward in October, and is profiled in depth onpage 28 of this issue of Passive House Plus.

Space heating, hot water and ventilation tothe dwellings is provided by Genvex Combi185 compact service units, which combine heatrecovery ventilation and an air-to-water heat pump,and were supplied by Total Home Environment.

Consisting of a terrace of three dwellings, thesepassive house units are part of a larger mixeddevelopment of affordable and open markethousing developed by Hastoe Housing Asso-ciation, and lie within the North Norfolk areaof outstanding natural beauty. As there wasno gas in the area, we were asked to installour compact service unit to not only provideheat recovery ventilation, but via the integralheat pump, all the heating and domestic hotwater requirements to each of the houses,Clarissa Youden of Total Home Environmenttold Passive House Plus.

She said that early monitoring indicates per-formance is as anticipated with heat load hov-ering around 8W/m2, temperature at a constant21C, indoor carbon dioxide averaging 650ppmand relative humidity averaging 55%.The NorthNorfolk coast has a significant proportion ofsecond homes, which has driven housing costs

beyond the reach of local people, and passivehouse was specified by Hastoe as a meansof addressing fuel poverty in the area.

The Genvex Combi 185 is a Passive HouseInstitute certified combined heat recoveryventilation unit with air-source heat pump.Youden said it can provide heat recovery ven-tilation at all times, even when the heat pumpis delivering hot water, and has a COP (coef-ficient of performance) of 4.5, according to

Total Home Environment. It is an all-in-onecompact unit, meaning the systems componentsare integrated.

A video profile of the Burnham Overy Staitheproject, with enthusiastic reports from residents,is also available online at tinyurl.com/bospassive

(above) The Passive House Institute certified GenvexCombi 185, an integrated heating, ventilation andhot water system designed for low energy buildings

The UKs largest manufacturer of chimneysystems, Schiedel Chimney Systems Ltd, haslaunched the Absolut XPert chimney systemwith an integrated insulated combustion airshaft. Designed for airtight homes, SchiedelAbsolut XPert is the first Passive House Institutecertified chimney system worldwide.

Suitable for use with all fuel types, with its GW3rated ceramic profiled liner, Absolut XPert offerscondensate resistance even after a soot fire.Airtightness is built into the system, accordingto Schiedel.

Schiedel Absolut XPert represents a compre-hensive solution to the four main challengesraised by modern heating technology combinedwith the latest energy efficient building techniques,said Schiedels residential sales and marketingmanager, David Wright.

The first challenge is condensation forming onthe chimney block. If external temperatures arevery cold, then moisture from the surroundingair can turn to condensation on the surface ofthe block, leading to damp spots and potentially

mould. The Absolut XPert system employs acore of foam concrete as insulation in the blocksthat form the shaft, ensuring that block surfacetemperatures remain above the critical dewpoint.

The second challenge is heat transmission tothe outside of the building (thermal bridging)via the chimney block. The top and bottom ofthe chimney are the two most sensitive areasfor heat transmission between the warm interior

of the house and the cold exterior. The AbsolutXPert system has specifically designed thermalinsulation blocks to prevent this.

Challenge three is the supply of air to the ap-pliance in an airtight house. When buildingsare efficiently sealed against draughts, com-bustion air has to be brought directly to theappliance. The Absolut XPert system has anintegrated insulated air shaft which suppliesthe appliance with the right amount of air itneeds for combustion, drawn directly from abovethe roof, minimising problems due to prevailingwinds.

Challenge four is how to cope with extremesof temperature and provide resistance to con-densate even after a chimney fire. The AbsolutXPert profiled liner has been tested and approvedwith a GW3 designation meaning that it issoot fire resistant, condensate resistant evenafter a chimney fire, and is corrosion resistanton gas, oil and solid fuel applications.

(above) Schiedels Absolut XPert Passive House Institutecertified chimney system

Schiedel launches first passive housecertified chimney system


News

Green Building Storelaunches new framelesspassive house windowsGreen Building Store launched a new passivehouse certified A-rated timber window range atthe UK Passivhaus Conference on 16 October.The new Progression range offers high perform-ance minimalist design with narrow sightlinesand 'frameless glazing' for passive house andother low energy projects.

When installed correctly, the Progression frameis hidden within the insulation at the wall junction,giving the appearance of frameless glazingfrom the outside. The proportion of glazing toframe, and the highly insulated narrow frames,contribute to Progression achieving the PassiveHouse Institutes A-rated window certification.

The Progression frame includes Thermowoodthermally-modified timber on external facings,which requires minimal or no maintenancethroughout the window's lifetime. Progressionuses cork insulation within the frame and lam-inated spruce for the internal facing timber.

Chris Herring, director of Green Building Store,commented: "Progression offers passive housedesigners a minimalist, contemporary designand passive house certified A-rated perform-ance. The range perfectly complements ourother high performance timber window rangesand we are delighted to be able to bring theProgression range to the UK for the first time."

According to Green Building Store, Progressioncan deliver whole-window U-values as low as0.68. Green Building Store are sole UK agentsfor the Progression range, in partnership withCzech manufacturer Slavona. The range hasalready been used on Green Building Store'scurrent West Yorkshire new build constructionproject, the Golcar Passivhaus.

(right) Progression, Green Building Stores new A-ratedpassive house certified timber window range

The passive house standard may be acceptableas an alternative method of compliance withIrelands stringent energy efficiency regulations,according to a leading expert in energy andconstruction law, leaving the door open to asimilar approach in the UK.

The equivalent of Englands Approved DocumentL1A, Irelands Technical Guidance DocumentL for dwellings demands 60% energy andcarbon reductions compared to 2005 levels,and requires renewable energy generation 10kWh/m2/yr of thermal energy or 4kWh/m2/yrof electrical. These changes were heavily in-fluenced by the campaigning work of thismagazines predecessor, Construct Ireland.

But as with the UK regulations, the detail oncompliance is contained within guidance doc-uments, rather than in the regulation of Part Litself. As legal expert Philip Lee writes in theIrish edition of Passive House Plus issue 9,guidance documents dont have the force of law,meaning alternative methods of compliance suchas passive house could conceivably be used.

Curiously, buildings that go beyond Irelands

60% energy reductions can struggle to meetIrelands renewable energy targets, as they maynot have sufficiently high energy demand toeasily meet the 10kWh/m2/yr renewables tar-get. Irish passive house advocates have longargued that dwellings meeting the standardshould not be required to generate such quan-tities of renewable energy.

According to Lee: It could be argued that theproportion of renewable energy to fossil fuelsinherent in the technical guidance documentcould also be applied to a passive house.Therefore, if a passive house consumes 50%less primary energy, then the proportion ofrenewables set out in the technical guidancedocument, namely 10 kWh/m2 (heating) and4 kWh/m2 (electrical energy), should be reducedby 50% to 5 kWh/m2 and 2 kWh/m2 respectively.

An alternative approach to the same inter-pretation of reasonable would be to look atthe net balance of brown energy that is pro-duced in a standard house and compare thatto the net brown energy produced in a passivehouse. Provided that the net amount of fossilfuel being consumed in the passive house is

less than that being consumed in a standardhouse then it could be argued that any actualenergy coming from renewable sources wouldmeet the reasonable test.

Lee also points out that under the RES Directive,EU members states must require the use ofminimum levels of energy from renewable re-sources both in new buildings and existingbuildings that are subject to major renovation,from 31 December 2014. This means, he says,that Irelands Part L will be in breach of the directiveif it is not quickly updated, as it specifies aproportion of renewable energy rather thana minimum amount. He warns that targets setin a guidance document dont suffice, giventheir non-mandatory status. The four regionsof the UK are also set to be in breach, basedon current policy.

Lee points out that the directive encouragesmember states to take into account nationalmeasures relating to substantial increases inenergy efficiency and to passive, low or zero-energy buildings when updating their buildingregulations to increase the share of renewableenergy.

Passive house: an alternativemethod of meeting Part L?

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News

Passive house certification crucialfor quality assurance Kym MeadLeading passive house expert and buildingcertifier Kym Mead has advised those procur-ing or building passive house projects of theimportance of having their building certified.

Mead is a director of his own consultancy,Mead: Energy & Architectural Ltd, which providespassive house certification and consultation,and is also an associate director of the UKsPassivhaus Trust. He is a former head of lowcarbon buildings at the BRE and is an architectby training.

Its about quality assurance, he said, speakingon the importance of certification. The designteam could overlook something that may havea negative effect on the buildings performance,or an honest mistake could be made. Certifi-cation is essentially a third party audit, makingsure that something hasnt been missed. Itsabout peace of mind for the client. Its alwaysadvisable to have the building checked overand signed off by a certifier at the design stage,so any feedback can be incorporated easily,and cost-effectively.

Mead believes the term passive house shouldonly refer to certified buildings in order to protectthe integrity of the standard, with the term passive

house principles being more appropriate forreferring to buildings that meet the requirementsof the standard in PHPP but arent certified.

Clients who build to the passive house standardbut dont get their project certified sometimescite cost as a reason for declining certification,but Mead points out the cost per square metrefor certification is small compared to other el-ements of a typical build. Its actually one ofthe cheapest things to do, he said.

Mead has completed an internship at thePassive House Institute in Germany wherehe was able to work closely with the institutesteam and gain valuable experience. He addedthat because in the UK the passive housestandard represents a level above whatsconsidered best practice, certification enablesclients to be certain this robust standard hasbeen met.

(right) Kym Mead argues that bringing in passivehouse certifiers at the design stage can deliver costsavings and avoid mistakes being made

Following a successful World Green BuildingWeek series of seminars and demonstrationsin September, Ecological Building Systems hasannounced a series of new training courses andseminars. This is timely with the latest revisionof the building regulations, increased activityin the construction sector and a demand for higherlevels of thermal performance in buildings, saidNiall Crosson, the companys technical engineerand certified passive house consultant.

The courses include a new Pro Clima IntelligentAirtight Systems training programme whichhas a particular focus on practically deliveringairtightness on site. This practical course willbe delivered by one of Ecological Building Sys-tems technical experts, Peter Smith, in com-bination with certified passive house tradespersonRoman Szypura of Clioma House. Roman isvery well known in the world of passive houseand has many years experience deliveringsome of the most airtight and lowest energyhouses in Ireland and the UK.

Ecological Building Systems will also once againbe delivering its highly commended BetterBuilding, Putting the Fabric First course. Thisis split into morning theoretical and afternoon

practical sessions. The morning building physicssection is delivered by Niall Crosson. Thepractical afternoon session is again deliveredby Roman Szypura. The course focuses on meet-ing the thermal requirements of the buildingregulations, key areas to consider when retro-fitting existing buildings, an introduction topassive house principles, and an overview of

airtightness and vapour control. This coursewill focus on both retrofits and new builds.

The courses will be held at the companysstate-of-the-art Centre of Knowledge in Athboy,Co Meath. The courses are also targeted atUK delegates, and the company can organisetransport to and from Dublin Airport. Given thecompanys vast experience using award winningproducts on pioneering low energy projects sincethe year 2000, Ecological Building Systems isin a unique position to impart its knowledgeto both building professionals and the public.

More information regarding these seminarsand training courses is available at: www.ecologicalbuildingsystems.com

Ecological Building Systems also provide freeconsultation and guidance, and its training centreis open for free viewing by appointment. The com-pany is always available to help guide buildingprofessionals through design detailing, productchoice and advice on installation.

(above) David Broderick of DB Plaster demonstratinghow to install Gutex insulation at the Ecological BuildingSystems Centre of Knowledge

Ecological Building Systems launch airtightness& fabric training programme


News

Green Tomato launches sash-lookalikeultra low energy window

Green Tomato Energy has launched a triple-glazed sash-lookalike timber window to the UKmarket. The window is designed to resemblea traditional sash window, making it ideal forhistoric buildings, while offering the thermalperformance of a modern ultra low energy window.

The windows top sash is fixed in in place soit cannot be opened, while the bottom sash openson a tilt-and-turn mechanism rather than thetraditional sliding sash. It was developed bythe team working on the Lena Gardens andPrincedale Road passive house retrofit projectsin London, where there was no other solution

that would meet the passive house airtightnessstandard and comply with the strict conservationcriteria laid down by the planners. Traditionalsliding sash windows are notoriously difficultto make airtight so arent suitable for passivehouse projects.

The Green Tomato Energy window has sincebeen used on the firms Enerphit project atBarmouth Road, London, which was profiledin issue eight of Passive House Plus, and thedesign of the window has continued to evolve.

The windows are made in a small workshop

in Cambridge, and according to Green TomatoEnergy, this means the usual reasons for delaysin supply to the UK (ie transport) are less ofan issue. The window features triple-glazing, alayer of gaskets for high levels of airtightnessand sound insulation, plus a low-e coating, argonfill and warm edge spacer bar. The window offersU-values of 0.58 for the glazing and 1.10 forthe frame, and a G-value of 0.55.

(above) The Green Tomato sash lookalike windowat the Barmouth Road Enerphit project in London,as featured in issue 8 of Passive House Plus

After the success of recent workshops in Londonand Edinburgh on passive house and low energybuildings, Advantage Austria has announcedplans for further workshops in 2015.

The exact venues for future events have yetto be decided but Peter Franklin of AdvantageAustria told Passive House Plus he is keen to

strengthen links in all regions of the country.

It was great to see so many initiatives on lowenergy building up and running in Scotland,especially the work that is being done by thecolleges network. We would love to hear fromorganisations keen to promote sustainablebuilding in other parts of the country who mightbe interested in hosting future events, he said.

More events are planned for Scotland too, whereFranklin said there is a lot of interest from theeducational sector as well as the local constructionindustry to fully understand the opportunitiesand challenges of low energy building.

Advantage Austrias mission is to get expertsfrom Austria and the UK talking to each other topromote better sustainable building practicesin both countries. In March, Advantage Austriawill bring a group of architects and engineersfrom Austria to exchange ideas with their UKcounterparts and learn about new develop-ments in the UK market. You can meet themat a forum at the Austrian Trade Commission

in London on 2 March or at the Austrian Pavilionat Ecobuild the following afternoon.

Some of Austrias leading low energy brandscontributed to events in 2014, included passivehouse window manufacturer Optiwin, airtightnesssystems provider Isocell, and external insulationsupplier Baumit. According to Conor Ryan ofOptiwin, the events offer an invaluable opportunityto help upskill the UK market in robust low en-ergy building. We look forward to continuingbespoke CPD events in 2015, he said.

For further information on the Advantage Austriaevents please contact Peter Franklin at AdvantageAustria at [email protected] information on Optiwins 2015 CPD eventscontact [email protected]

Pictured at the Advantage Austria workshop in Edinburghin October are (top, l-r) Baumit UK MD Alan Haugh;Isocells UK operations director Stuart Prouse; Optiwinhead of UK operations Conor Ryan; award-winningpassive house architect Kirsty Maguire; and AdvantageAustrias marketing officer Peter Franklin

Advantage Austria to run passive CPD events in 2015

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News

Soltherm chosen to externally insulateexposed Welsh propertiesOver 300 houses in the villages of Carmeland Y Fron, in North Wales, are currently beinginsulated using the Solix Soltherm HD Weatherexternal wall insulation system as a part of awider retrofit programme. The project is beingcarried out under phase two of the Welshgovernments Arbed energy efficiency pro-gramme, which is being delivered by contractorWilllmott Dixon in north and mid Wales.

Waldemar Malec of Solix told Passive HousePlus that while most external insulation sys-tems are not applied during the winter, be-cause they require dry conditions, SolthermHD Weather was developed for the Britishand Irish climates and is suitable for applica-tion even in damp weather. He said that thesites at Carmel and Y Fron are a case in point,as they are highly exposed to the elements.

It dries by chemical reaction rather than evapo-ration, Malec said of Soltherm, and is wash-off resistant within a few hours. Soltherm EWIsystems are cold bridge free and can be appliedbelow the DPC level, Malex added. Soltherm,an EPS system, was also recently used to insulate130 properties in the Welsh village of Llandysulfor Ceredigion County Council, another Arbedproject.

Malec believes the benefits of external insulationover internal insulation are still not as widelyknow as they should be not only in termsof cold bridging, but as regards moving the dewpoint towards the outside of the wall build up,unlike internal insulation, which in certain cir-cumstances can move the dew point to thespace between the insulation and the origi-nal wall. He also pointed out that, by reducinginternal floor area, internal insulation can cuttens of thousands of pounds off the value ofa home.

Malec said that all Soltherm systems are pro-tected from the typical fungi, mosses and algaesthat can grow in the UK & Ireland. Solix hasalso just launched Soltherm HD Ultimate, animpact-resistant external insulation systemthat can withstand over 120 joules of force. Itoffers higher strength than a brick wall, Malecsaid. Soltherm is supplied through differentdistributors throughout the UK & Ireland, withSolix providing training, technical support andsite supervision.

(above & below) The Soltherm external insulationsystem was applied to 130 homes in the Welsh villageof Llandysul

Poor design &install threatenHRV market ProAirGalway-based heat recovery ventilation man-ufacturer ProAir has warned that poor qualitydesign and installation poses a threat to theHRV market in Ireland and the UK. The com-panys David McHugh told Passive HousePlus that a lack of quality standards meansystems are being improperly specified, de-signed and installed. He said ProAir hadbeen asked to advise on a number of build-ings where these issues had led to inade-quate ventilation, causing condensation andmould.

Quite a lot of print space has been allocatedto the common concepts attached to low energyconstruction such as insulation, draught-proofingand the elimination of cold bridges, but relativelylittle has been written on the other essentialcomponent, heat recovery ventilation, hesaid.

In particular, HRV design and installation.The British building regulations Part F stipulatesthat all systems must be commissioned andthe results furnished to building control. Becauseof this, the Building Research Establishmenthave published recommendations on com-missioning these systems, which indeed makesense, but it is impossible to commission sys-tems that have been improperly designed,specified and installed," he said.

McHugh said that while EN standards do existon the methodology for testing HRV systems,there are no standards on the proper speci-fication of these systems, or on suitable ductingsystems.

McHugh said one common issue is HRV ductingbeing installed outside a building's thermalenvelope. All supply and return ducting shouldbe in a service cavity within the insulation andairtightness envelope of the building. At a mini-mum, the ducting should be at least withinthe insulation envelope.

McHugh said that, post building boom, storiesof poor HRV jobs emerge every day, and this isthreatening the wider reputation of the sector including for quality suppliers and installers.He suggested a national industry body couldproduce guidelines on the design, specificationand installation of HRV systems and ducting.

These guidelines need to be backed up byresearch and solid experience. Maybe this iswhere [a state body] needs to step in and fundthis independent research, perhaps throughmasters programmes, he said.

HRV has been proven to work and properlydesigned and installed systems can delivercontented customers and energy bill savings.

The Zero Carbon Hubs recent work withindustry has found extensive evidenceof a considerable performance gapbetween the energy use of new homesas-designed and the actual use of thecompleted building. This gap occurswhen a home requires more energythan was predicted during its design,before taking into account the behaviourof occupants.

This gap represents a significant risk tothe UKs carbon reduction commitments.It has the potential to result in higherthan expected household energy bills,undermining buyer confidence in new(low carbon) homes. As we approachthe zero carbon homes target of 2016,housebuilders are producing higherperforming homes and need to beconfident that they perform as intended.

Since January 2013, the Zero CarbonHub has carried out an extensive studythat involved over 160 experts and21 live house building sites acrossthe UK. This project forms the initialphase of industry activity to addressthe performance gap, the ultimateaim being that by 2020 a minimum of90% of all new homes meet or performbetter than their design.

At the start of the research there wasa misconception that the performancegap was simply caused by inaccuracieswithin energy modelling software andpoor construction practice on site.The evidence review report showedthat a gap can arise due to issues atvarious stages of the building process.Throughout this practice, a number ofcross-cutting themes keep recurring:unclear allocation of responsibility;poor communication of information; anda lack of understanding, knowledgeand skills.

As part of the wider research, a housebuilding process review was developedand undertaken throughout 2013 -2014, which included detailed analy-sis of over 200 plots across 21 sitesof different sizes throughout the UK.Two multi-disciplinary teams led byindustry experts (including myself)spent a week analysing each site,comprising: project team interviews,a construction site walkthrough, a

design review and SAP audits. Thisprocess was then supplemented ona number of sites with on-site testingusing thermography and air-testingacross a selection of the plots.

The site inspections analysed severalhundred elements of the buildings atall stages of construction. Any deviationsfrom the design were fully documentedwith good and poor practice noted, andgraded in terms of impact on as-builtperformance. The energy performancewas then analysed using SAP andsite findings to ascertain the gap interms of KgCO2/m2 (% improvementover dwelling emission rate). This couldbe compared to the original SAP andenergy performance certificate (EPC).

The review has identified 15 priorityissues that require action to begin toaddress the performance gap. Theseinclude: planners failing to understandthe energy challenges, current materialand product testing protocols not re-flecting 'real world' dynamic conditionswhen calculating thermal performance,procurement teams failing to considerenergy related site skills when reviewingtenders, and site managers consideringenergy related issues as a comparativelylow priority during their quality checks.

For the house building industry, researchand development is needed to createinnovative and commercially viablemethods to test and measure the en-ergy use of completed homes, so thatindustry can understand their trueperformance. The industry also needsto embed energy literacy across thesector, with all professionals and op-eratives undertaking energy training andupskilling. As a result of the project,the government has indicated it is keento work with industry to develop a newconstruction details scheme which willbe set up to provide assured, as-builtenergy performance for the mostcommon major building fabric elementsand junctions.

In place of immediate additional reg-ulation, the government must clearlyindicate that it expects the constructionindustry to act now to ensure that theperformance gap is being addressed;industry must then commit todemonstrating that this has beenachieved by 2020. The complianceregime needs to be strengthened, witha number of refinements to energymodelling and verification procedures.Lastly, the government should stipulatethat only energy-certified operatives andprofessionals be employed on publicland developments from 2017, whichwould accelerate demand for industry

developed qualification schemes.

While the project did not specificallylook at the benefits of the passivehouse methodology, the principlescan play a part in reducing the per-formance gap. The site inspectionsand interviews have witnessed goodpractice stemming from the passivehouse standard, and some of thishas fed into the recommendations forindustry and government. However ata larger scale, passive house projects stillsuffer the same issues and demonstratea significant performance gap.

Common problems are found at groundfloor and foundation junctions, whereinsulation is inconsistent or missingand significant thermal bridging occurs.Other areas causing deviation from thedesign are poor installation of insulation,incorrect window performance, optimisticU-values/Psi-values and unaccountedthermal bridging. Site inspections maynot pick up on optimistic product per-formance, site installation factors suchas rain soaked insulation, hiddenthermal bridges, site tolerances, levelthresholds, or window performanceand installation.

The passive house methodology canassist in helping to reduce the per-formance gap with early stage con-sideration of energy performance androbust compliance and commissioningprocedures. Site inspections are alsocrucial to delivery on site, but this isdifficult to ensure on a larger scalewithout significant extra resources. Ithas proven successful on small sitesof less than 20-30 units, but getsharder on larger sites with hundredsof workers and more units to bemonitored. In Belgium and other partsof Europe, passive house has beendelivered on a large scale with the helpof offsite construction, but the UK in-dustry currently has very differentpriorities and procurement methods.

With the completion of the end of termreport, the proposals are now movingforwards, to 2020 and beyond. If youwould like more information on ZeroCarbon Hubs current projects, or ifyou have further evidence or projectsthat could be included in the researchon the performance gap, please getin touch and sign up to the newsletterat www.zerocarbonhub.org

Tom Dollard is head of sustainabledesign at Pollard Thomas Edwards. Heleads a research team which inspected21 sites for the Zero Carbon Hubperformance gap report throughout2013-2014.

How to close the performance gapThe gap between designed and real-life energy performance in new dwellings is a significantthreat to the UKs plans to deliver zero carbon homes. Architect Tom Dollard describes researchby the Zero Carbon Hub to better understand this performance gap and how to fix it.

The industry needs toembed energy literacyacross the sector

Taller Passive House,

Mexico CityPhotos: Moritz Bernoully

Mexicos first certified passive house is the retrofitof a roof-top apartment in the countrys capital.This small space was originally built cheaplyin 2007, mostly with plywood.

But while living in Germany, Mexican architectAlejandro Herrera trained in the principles ofenergy efficient building. When he returned tohis homeland in 2011, he decided to upgradethe apartment his home to the passive

house standard. Herrera led the project alongwith Maris Igea, his partner at Inhab SustainableArchitecture.

One of the biggest challenges for the architectswas the lack of a passive house supply chain,in terms of skills or products, in Mexico. Contractorshad to be trained in passive house principles,while experts travelled from overseas to adviseon the build.

But in some ways, meeting the passive housestandard was easier in the warm Mexican climate.The apartment achieves a space heating demandof 15 kWh/m2/yr with double-glazing, with wall,roof and floor U-values of between 0.3 and 0.4.

Heat recovery ventilation was not required either,just simple mechanical extract ventilation.

The team insulated the entire building envelopewith EPS, and airtightness is provided by theOSB along with Siga tapes and membranes.Now, a single electric heater is enough to heatthe whole apartment.

The architects say: A lot of collaborative worktook place, it involved a big effort and a deepcommitment, and it was all worth it. The finishedbuilding is not just the first certified passivehouse building in Mexico, its also the first cer-tified passive residential building in all of LatinAmerica.

INTERNATIONALSELECTIONThis issues selection features ultra low energy buildings from Mexico, Germany, New Zealand and Italy,and illustrates how widely the energy efficiency specification can vary in different climate zones.

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Day care building,

Georg-August-University,

GermanyPhotos: Jochen Stber, Hamburg & Olaf Baumann, Hanover

Completed in 2010, this day centre for GttingenUniversity was designed by Despang Architekten,who describe it as a hybrid of landscape andarchitecture. The buildings north and westfacades are earth-bermed, but the south facadeforms a passive solar curtain-wall with views tothe outdoor playground and landscaping. Thisglazed facade is comprised of a timber-aluminiumpost-and-beam structure with extensive triple-

glazing.

The walls and ceilings were constructed fromlarge, prefabricated concrete elements to minimisethe number of joints. The walls were externallyinsulated and the building is topped with a greenroof, while the earth-bermed surfaces help toreduce energy loss, too. The building achievedan airtightness result of 0.43 ACH, comfortablywithin the target for passive buildings, and hasa space heating demand of 15 kWh/m2/yr.

The material palette inside concrete, glass,spruce wood, linoleum was in part chosen toavoid off-gassing materials, and the concretefinishes are extended outside the building via

thermally broken concrete frames.

These external concrete elements are functionaltoo: they provide seating at their bases, guardrails for the roof, and static shading. The concreteframes also contain dynamic shades whichcan be pulled down in summer to controloverheating and glare.

Passive solar gain is the buildings main heatsource, backed up by the campus-wide dis-trict heating and standalone water heaters.During summer nights, the building is flushedwith cool air. But when the shades are up inwinter, the low sun penetrates deep inside to warmup the thermally massive concrete structure.

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Whanau, Auckland,

New ZealandPhotos: Simon Devitt

New Zealands first certified passive housestarted out typically enough: architect DarrenJessop was approached by Phillip and CarolynIvanier, a couple wishing to build their firstfamily home. They wanted a modern open-planfamily dwelling, and a degree of separationbetween the adult and child spaces.

But with the design already settled, and promptedby New Zealands low building insulation standards,

the clients made a game-changing request: thatthe dwelling meet the passive house standard.

The windows were minimised on the southside of the home where they would loseheat in the southern hemisphere and over-hangs were extended over the north-facingglass to prevent overheating.

The roof and double-stud walls of this split-leveltimber frame house are insulated with glass-wool, but in the subtropical climate of Auckland,respective U-values of 0.37 and 0.23 wereenough to meet the passive house standard, aswere double-glazed windows. Below groundlevel, the basement walls are of insulated con-

crete formwork. Meanwhile the airtight wrapof the house is provided by a Proclima Intellovapour membrane.

Ventilation is provided by a Zehnder heat re-covery ventilation system, while an air sourceheat pump delivers hot water. The house alsohas rainwater collection and solar photovoltaics.

On completion of the project, Jessop estimatedthat meeting the passive house standardadds around 10 to 12% to build costs in NewZealand. But he says the occupiers will re-coup much more than this amount if they livein the house over its lifetime while enjoyinga warm, comfortable, healthy home.

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Passive House Pichler,

Pfitsch, ItalyPhotos: Arthur Pichler

This striking certified passive house in the ItalianAlps was designed by architects Arthur Pichlerand Walter Colombi. The brief was to design asustainable, open-plan building with ultra lowenergy consumption.

The top floor of the building contains a singleflat with its own entrance made possible bythe sloping site while the two-storey flatbelow leads directly onto the garden. In winter,the glazed south facade acts as a solar stove,the architects say, to deliver passive solar heating.Orienting the building to the south shelters itfrom the harsh northerly alpine winds too.

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Passive solar gain and heat recovery ventilationare the main sources of space heating. There isalso a small Windhager wood pellet boiler thatprovides hot water, and can deliver heat throughthe ventilation system in the coldest weather.

The timber frame walls and roof are insulatedwith Thermohemp, while the floor has a meaty420mm of extruded polystyrene insulation.The buildings annual heat demand is just 9kWh/m2/yr, well inside the passive house markof 15, and airtightness is 0.4 air changes perhour. Passive House Pichler also has a greenroof that helps to keep it warm in winter andcool in summer and soaks up rainwater too.

And as one of its architects, Arthur Pichlerhad special motivation to get the house right:he lives on the lower floors with his youngfamily, while his parents live upstairs.

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Three award-winning affordablehomes in scenic North Norfolk haveachieved passive certification whileembracing a unique local style ofarchitecture.

Words: Chris Parsons, Parsons

+ Whittley Architects

The beautiful and unspoilt North Norfolk coastprovides a haven for visitors, not just in the

Passive fishermens cottages on Norfolk coast

summer months when the population swellsdramatically, but also out of season for thoseseeking a tranquil idyll or perhaps enjoyingthe ornithological diversity that the area provides.This in turn has led to a thriving second homecommunity, which has had the unfortunate effectof making affordable housing for local peoplevery difficult to find. It was this background thatled Hastoe Housing Association, in conjunctionwith the parish council, to bring forward a schemefor much needed local affordable housing in 2007.

A suitable site was provided by the local parochialchurch council on the western edge of the villageon the main approach road into the settlement.

Being in a designated Area of OutstandingNatural Beauty and within a local conserva-tion area meant that the design quality of thescheme had to be exemplary. A context studyand careful consideration of local materialsdrove a scheme that also needed to take accountof views into and out of the settlement. Planningconsent was eventually granted in 2009 althoughlegal matters prevented the scheme from get-ting underway until 2013.

By then Hastoe Housing were specialists in thedelivery of passive house, having delivered theaward winning Wimbish affordable housing schemein 2010 and the subsequent Ditchingham passivehouse scheme. So it was no surprise wheninstructions were received to develop the schemeto the passive house standard, despite thefact that planning had already been gained forsomething much less ambitious. Hastoe ex-pound passive house mainly because it is highlyeffective at relieving fuel poverty, a huge prob-lem in their sector. They also find that passivehouse delivers other advantages such as fewervoid periods and less ongoing maintenance,while keeping operational energy and the resultantcarbon emissions low.

As architects for all of Hastoes earlier passivehouse schemes, Parsons & Whittley were un-fazed by the challenge, but the timescales re-quired meant that planning amendments hadto be kept to a minimum. We were fortunateto have a planning authority who understoodpassive house, and who were keen to workwith us to deliver the scheme while maintain-ing the design quality. We had modelled theoriginal scheme on the traditional vernacularof fishermens cottages, and those guys knewa thing or two about working with the elements.We already had a compact form and good southorientation, with very well sheltered, minimalnorth facing windows.

So the biggest challenge at Burnham OveryStaithe was to take a scheme that had con-siderable design constraints already imposed,that had not been designed as passive house,and deliver it to one of the most exacting energyefficiency standards.

A quick review of the site identified that whilethe terrace houses could be adapted to thepassive house standard, the three remainingunits had a poor orientation and form factor andwere unlikely to achieve the passive housestandard cost-effectively. Consequently it wasdecided to concentrate the passive house ap-proach only on the three two-bed terraced units(comprising a total of 228 square metres ofgross internal floor area). All of the affordableproperties, including the passive house units,needed to achieve Code for SustainableHomes level four.

First on the checklist was wall thickness. Takingthe scheme from 300mm walls to 500mm grewthe footprint. Similarly roof insulation and spacefor ductwork was always going to push theroof higher. The terraced homes had certainaspects in their favour though, such as thecompact form (a terrace of three units will tend tohave a good form factor, or area to volume ratio),the orientation, and the window arrangement,which needed almost no change.

The use of brick/flint faced walls under a claypantile roof was fixed, and of course necessarygiven the sensitivity of the site, so cavities wereexpanded to take a full 300mm of insulation.

Despite its coastal location, the site is relativelywell sheltered for a full cavity fill. The founda-tion became a raft type slab to accommodateadditional insulation, although supporting a200mm flint and block outer leaf without a thermalbridge led to some interesting discussionswith the engineers, eventually resolved throughthe use of an independent strip footing supportingthe outer leaf.

Interestingly, the additional wall thicknesshelped to bring the eaves height down despiteraising the roof to accommodate the MVHRductwork and service voids. The use of thin-ner PIR insulation at the eaves helped avoidthe otherwise typical thermal bridge so oftenfound at eaves details.

The thicker external skin, particularly wherefaced with local flint, helped to recess the win-dows to provide shade and a better thermalperformance, while actually enhancing thedefinition of the fenestration. Segmental archesutilised precast concrete or self-supportingarches and the wider frame of the passivehouse windows kept this detail looking neat.Munster Joinery triple-glazed timber windowsprovided the necessary glazing performancewhile retaining a traditional appearance.

Taking the lead from the external finishes, theconstruction generally followed a masonryapproach, for the advantages of thermal massbut also because the skills and materials arefreely available. In addition, wet plaster pro-vides an ideal airtightness membrane, leav-ing the consideration of this aspect down tojust the critical junctions and the use of amembrane arrangement on the underside ofthe roof trusses.

Another limitation of the pre-fixed design cen-tred on the space available for the mechani-cal infrastructure. Rural exception sites suchas these rarely have ideal fuel supplies, andchoices were limited in this case. Initially thescheme had been designed to consider com-munity biomass, with a separate outbuildingon site to house the equipment. But fuel sup-ply concerns and a more detailed considera-tion of carbon emissions from biofuels led tothis being discounted. Eventually Genvex185L compact units comprising an MVHR andexhaust air heat pump were chosen, givingthe additional advantage of economy of space.They are positioned on the first floor of eachhouse and the MVHR inlet and exhaust passthrough the roof, with supply and extract fit-ting within a compact service void just belowthe trusses, or within the space of the metalweb floor joists.

Normally a passive house might benefit froma deep roof overhang to provide summer shading,but once again the pre-fixed design prohibitedthis, so a cooling strategy was developed whichincluded a sensible window opening allowancealong with external blinds on the larger southfacing glazed areas.

The project was tendered during the earlysummer of 2013 once the design was fullycomplete, (to RIBA work stage F), whereupona local builder, EN Suiter, was successful andstarted work straight away. The contractorsapproach formed an essential part of the suc-cess of the scheme, with an openness andwillingness to learn and consider the impor-tance and sensitivity of elements that are normallytaken for granted. The site quality demands

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of passive house were recognised and em-braced, making the delivery of this exactingstandard much easier. Coordination betweendesign and site team continued throughoutthe build and ensured that milestones werepassed without difficulty. The required air-

tightness of less than 0.6 air changes wasachieved at the first attempt and the site wascompleted and ready to occupy in February2014.

One of the lessons learned from Hastoes previousschemes is how to hand over something asinnovative as passive housing to ensure thatoccupants get the most out of the dwellings.At Burnham Overy Staithe this was achievedthrough the production of a small and simpleplain English operation guide included in thehome owners manual.

On move-in day the dwellings were set upand working so that the new occupants couldconcentrate on all the other stressful eventsthat moving house entails. Then a couple ofweeks after moving in, when the excitement

of the move had subsided, Hastoe and the ar-chitects returned and spent an hour or so witheach family taking them through the controlsand the heating and cooling strategy. One ofthe most important aspects here is to ensurethat occupants experience the controls them-selves and get to play with them while expertsare around to guide and assist. This processis then repeated at the change of season toensure the differences between heating andcooling a passive house are well understood.

At the same time as the handover, monitorswere installed with the occupants consent, tomeasure temperature, relative humidity andCO2. Early data shows that the houses areworking to the passive house design intent,with space heating running at just under 9W/m2.

Passive house certification was obtained inJune 2014. The overall cost of 1,745 persquare metre includes the contractors over-heads, significant external works and profes-sional fees. The actual cost of the buildingsthemselves comes out at around 1,022 persquare metre, which, given the additional ma-terial and design quality necessary in this lo-cation, represents a cost-effective delivery ofthe passive house standard.

The project has been well received by localsand passive house enthusiasts alike, and wasthis years winner in the UK Passivhaus Awardsarchitectural design category. Most importantly, theBurnham Overy Staithe passive houses demon-strate that this most demanding of energy

new build

Hastoe expound passive housemainly because it is highly effectiveat relieving fuel poverty

(top left) the raft foundation which was insulated with 400mm Styrofoam XPS insulation; (middle left)the cavity walls were insulated with Isover Hi-Cav 32 glass mineral wool insulation and clad with brick,while Cavalok BigBlok insulated cavity closers and Ancon Teplo Tie basalt wall ties eliminate thermalbridging; (bottom left) airtightness measures included the installation of a Pro Clima Intello membraneand a suspended ceiling system to house ductwork; (above) the three terraced homes all obtained passivehouse certification in June 2014; (p33) (top) it was decided not to aim for the passive standard with theother three units at the site, as they had a poor orientation and form factor; (middle) Munster Joinery Eco-Clad timber aluclad windows provided the necessary performance while retaining a traditional appearance

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and comfort standards need not be compro-mised by architectural constraints and can bedelivered in a wide range of traditional idioms.

SELECTED PROJECT DETAILS Client: Hastoe Housing AssociationArchitect: Parsons & Whittley Contractor: EN Suiter & SonsProject manager: AecomM&E designers: Engineering Services ConsultancyCivil & structural engineering: Rossi LongPassive house certification:Mead Energy & Architectural Design Heating & ventilation system:Total Home Environment Electrical services: Alpha Electrical Windows: Munster Joinery Wall ties: AnconCavity closers: Cavalok Stainless steel fixings: HelifixMineral wool insulation (cavity wall): IsoverMineral wool insulation (roof): KnaufXPS insulation (floor): DowPlaster (for airtightness) & wallboard: GypsumAirtightness products: Pro ClimaAirtight window tapes: Iso ChemieMVHR / heat pump: Genvex

Want to know more?The digital version of this magazine includes

access to exclusive galleries of architectural

drawings. The digital magazine is available

to subscribers on www.passive.ie

new build

PROJECT OVERVIEW:

Building type: Terrace of three 76 sqm passivetwo-bedroom homes (the wider developmentincluded three further units).

Location: Burnham Overy Staithe, on the NorthNorfolk Coast, in an Area of Outstanding NaturalBeauty

Completion date: Feb 2014

Budget: Part of a larger scheme totalling980k. Actual build cost 1,022 per sqm excludingpreliminaries, externals and fees

Passive house certification: Certified

Space heating demand (PHPP): 14 kWh/m2/yr

Heat load (PHPP): 9 W/m2

Primary energy demand (PHPP): 108 kWh/m2/yr

Environmental assessment method: Codefor Sustainable Homes Level 4

Other standards & awards: The houses alsodeliver against the Homes and CommunitiesAgencys housing quality indicators, whilecomplying with the Joseph Rowntree Life-time Homes standard and achieving 14 pointsunder CABEs Building for Life standard.

Airtightness (at 50 Pascals): 0.60 ACH

Energy performance certificate (EPC): Pending

Measured energy consumption: 12 monthsnot available but four months shows 8.72W/m2 heat load

Thermal bridging: Thermal bridging gen-erally eliminated. Worst-case 0.1 psi valueemployed for the full length of the party wall,and for the Helifix stainless steel fixingsused for the small area of timber boardingbetween the windows. Cavalok BigBlok in-sulated cavity closers and Ancon Teplo Tiebasalt wall ties also used.

Ground floor: Raft foundation with 400mmStyrofoam XPS insulation. U-value: 0.078

Brick-clad walls: 100mm facing brick (or200mm flint/backing block) external leaf, fol-lowed behind by 300mm cavity fully filledwith Isover Hi-Cav 32 glass mineral wool,100mm dense block inner leaf and GypsumHardwall plaster internally for airtightness.U-value: 0.096

Timber clad walls: 13mm plaster; 100mmblockwork; 200mm Isover Hi-Cav insulation;100mm Kingspan Kooltherm K5 insulation;38mm battens/cavity; 19mm timber boards.U-value: 0.104

Main roof: Tiles and wind-tight space on400mm Crown Loft Roll 40, followed under-neath by 100mm Crown Loft Roll 40 betweenbottom chords of truss, 13mm OSB, Pro ClimaIntello membrane, 120mm airspace/servicevoid, Gyproc wallboard. U-Value: 0.079

Pitched roof, sloping ceilings:12.5mm GyprocWallboard Duplex; 300mm Kingspan KoolthermK7; 18mm OSB; membrane; battens; tiles.U-value = 0.079

Windows & doors: Munster Joinery EcoClad120 triple-glazed timber windows with alu-minium cladding. Warm edge spacers, low-e glass and dual seal for airtightness. PassiveHouse Institute certified. Installed window U-value: 0.85 (as per PHI certificate). Also MunsterJoinery EcoClad doors.

Heating & ventilation system: Genvex Combi185L unit. Passive House Institute certified.Combines heat recovery ventilation with anair-to-water heat pump.

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Ledbury passive houseembraces warmth, wood & lightFor Ruth Busbridge and her builder Mike Whitfield, aiming for the passive house standard was justone part of an environmentally conscious approach that put natural, healthy materials to the fore.

Words: Kate de Selincourt

Entering Ruth Busbridges light, warm housein the suburbs of Ledbury, Herefordshire, youimmediately leave the humdrum mix of post-war semis and 70s infill behind. You have clearlyentered an alternative space. Drying fruit andherb teas line the shelves, there are warm naturalmaterials, colourful hand-made textiles, andan altogether welcoming, eco feel.

The style of the house inside and out is recog-nisable as what Ruth calls modern organic white paint and render, and natural wood forcladding, window frames, work surfaces, doorsand stairs. The carpentry is beautifully finished,with charming bespoke touches: hand-shaped wooden door handles and latches,wobbly cleft oak balustrading, and a secretsliding cupboard under the stairs all craftedby builder Mike Whitfield and his team.

Not everyone expects a passive house to belike this and indeed, when Ruth first heardof passive house, she didnt think it was rightfor her. When I first heard about passive house,my initial reaction was eurgh I wouldnt wantto live in a hermetically sealed house, she says.

However, that was before she had learned muchabout it. Id been planning to build a house forfour years, so I did a course at Cat [the Centrefor Alternative Technology in Wales], and I joinedthe local AECB [the Association for EnvironmentConscious Building], which is how I met Mike,and passive house was just filtering in. ThenI went on a study tour to Germany and becamemore interested in passive house. The moreI heard, the more I thought it made sense.

Mike Whitfield has been building beautiful, en-vironmentally conscious buildings from naturalmaterials for decades he was the contractoron the conversion of a derelict barn on theDuchy of Cornwalls Herefordshire estate intothe new HQ for Architype West, for example.As a main contractor, Mike Whitfield offeredRuth the ideal approach, with his preferencefor natural and low-impact materials, combinedwith excellent energy performance, in a styleshe was drawn to. I had seen some of his workbefore. It was beautifully finished, and I preferthe natural look.

By the time Ruth approached him, passive housewas becoming a valued tool in Mikes missionto construct buildings that are comfortable,healthy and low-impact: We had been doingenergy efficient buildings anyway, and theAECB were developing their silver and gold

standards, which were also moving in thesame direction, Mike explains. He then startedto work on retrofits and extensions with thermal-bridge-free details and passive house tech-nologies such as MVHR.

Ruth told him she wanted a low energy house,but Mike advised spending a bit more and buildinga passive house. As a technically minded per-son herself (she is an IT professional), Ruthwas not interested in leaving the crucial partsof design and analysis to others, but insteadenrolled on a passive house consultant courseso she could be fully involved. There she metarchitect Janet Cotterell of CTT for a second time(they had been on the same course togetherat CAT), and hired her to produce the drawingsfor planning, and to work on the early stagesof design.

Once planning permission was secured, Janet,who is based in London, was able to hand overto Mike Whitfield. Mike took on the constructiondrawings, and took the lead on site. It was abit of an unusual contract in that respect, butI had seen the work Mike had done, and Ithought Ruth wont have any problems shewas so lucky to have him as her contractor,Janet says.

Ruth also found specialist heating and venti-lation designers and suppliers through theAECB: Because of the collaborative atmos-phere in the organisation we never felt we wereon our own, Ruth recalls. The expert advicefrom Alan Clarke and Nick Grant and from GreenBuilding Store, on designing and sizing theheating, hot water and MVHR, and ongoingsupport with PHPP, were invaluable. I couldnthave done it without them.

This was the first chance Mike had to build topassive house certification, and he was pleasedto take on the job because Ruth shared hispreference for low impact, natural materials.The timber frame, which Mike built on site, isinsulated with cellulose and clad in a mixtureof Douglas fir and lime render, and roofed withreclaimed slates. I would ideally also haveliked an alternative to EPS under the floor, butthere wasnt really any alternative that was af-fordable and the EPS works really well,Ruth adds.

The timber-frame build-up has a breathableconstruction, becoming more vapour perme-able from the inside outwards. This meansthat if any water does get in to the structure,

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it will dry out. The walls and roof are both in-sulated with Warmcel cellulose insulation. Mikesays: I have used Warmcel for very many years,we have had our own blowing machine for a longtime and have never had problems. After it hasbeen pumped in it packs really densely, almostlike cork. It is hard to imagine it settling, for instance.

One of the early design decisions was thesize and shape of the house, which is a kindof fat L shape, with a porch. Ruth recalls: Wewere also considering a smaller house, butopted for this shape and size [around 130 squaremetres] so we could have an extra bedroomand bathroom, and so get an income fromhaving lodgers.

As Mike Whitfield points out, this shape ismuch more involved to build than a simplerectangle: there had to be extra drainage andmore junctions, and inevitably it added to thecost. As architect, Janet Cotterell was alsokeen to keep the form as simple as possible:Before she settled on passive house, Ruthwas considering a more complicated shape for my part though I would have been happyto make this even simpler. I think a plain rec-tangle would have looked fine!

Despite the more complicated form, however,Ruth observes that making the house biggerdid make it easier to meet the passive housestandard. She adds: I was very clear I wanted lotsof daylight, and light from two sides in everyroom, which means not all the windows leadto net heat gain. We also have the upstairs ceil-ings going up into the roof, which does add tothe heated volume and heat loss area. So toensure the passive house standard was met,we have 400mm of insulation in the walls andthe building also had to be extremely airtight.

The original plan was for the OSB to form theairtight layer in the walls, but a preliminaryblower door test revealed the board was notquite as airtight as hoped. So I decided weshould go for belt and braces with an additionalmembrane over the walls, Ruth says. By thatstage the internal walls were already up, andadding a membrane to the roof would havebeen been tricky, so the OSB still forms theair barrier here.

Ruth says: I don't know if we really neededthis additional membrane [in the walls] but Ididn't want to risk not getting it certified. In theend our result was 0.24 so perhaps it paid off.Mike reckons we could easily have got 0.2 ifwe'd remembered to seal the shower trap whendoing the final test!

Planning rules meant the house had to face

the same way as others on the street, so itdoes not have a direct south-facing facade.The off-due-south angle means all glazinghas east or west elements, which makes it abit harder to control overheating.

Looking back Ruth wonders if perhaps smallerwindows would have made the design easier.I think I would still have had ample daylight,but it would have been cheaper, and with lessheat loss in winter and less unwanted gain insummer. Though vast windows seem to bede rigeur in some higher-end self-builds, Ruthdoes not feel they are necessary. You dontwant to live in a goldfish bowl, do you?

Like pretty much all passive buildings thehouse is beautifully quiet you completelyforget about the busy road outside, which issomething Ruth really values. Its so peace-ful in here, she says. Ruth named the houseWahroonga after a suburb in Sydney where sheonce lived. We liked the sound of the name,but we were certain it was perfect when welooked up the meaning of the aboriginal word it means 'home.

Ledbury is quiet at night, but the traffic doesbecome noticeable in the morning in hotweather when windows are opened for nightcooling. Ruth would like to fit some summershading (omitted at the time of building forcost reasons), or perhaps install a skylight atthe back for faster purge ventilation, partly soshe can keep the windows closed more of thetime, and enjoy the tranquillity.

She adds: A low but acceptable risk of over-heating was predicted by PHPP [at 2.5% ofthe time, well within the limits set in the stan-dard], so I took a calculated risk in not dealingwith this at build time. But actually, if, like me,you find 25C uncomfortably warm, I recommendyou take any overheating risk seriously fromthe outset, and mitigate against it.

The house is hitting its energy targets, accordingto Ruths careful records, with measured primaryenergy consumption at 74 KWh/m2/yr (thepassive house design target is 120). This is asyou would expect in a house with relatively lowoccupancy and with mains gas and solarhot water. Energy bills are correspondingly low.

When you ask Mike Whitfield what aspect ofthis job that he felt was most successful, hisimmediate response is the lovely client. Thoughthis might sound flip, it goes to the heart of whatMike has learned over 30 years in construction.In the end, its only about the people, he says.

You just want to be able to enjoy the job.

Sometimes the anxiety level of the client isjust so high that no matter how good a job youdo, there is grief. Ruth agrees: I couldntimagine working with any other builder. It wasstressful of course, but I loved doing it andwould do it again.

Both counsel against trying to work with ateam who are not all committed to the sameoutcome. Mike warns: If you are intent ondoing passive house its important to find abuilder who is up for it properly, plus all theconsultants, the architect, everyone. If youare trying to drag anyone along you shouldntbother. Sometimes Ill get approached by anarchitect who is not really committed, but theythink that if they get me to build it, it can be apassive house.

Ruth has experienced this too, now that sheis putting her passive house training to workfor others as a consultant: People come tome with a design, and say can you make thisa passive house? But they dont want tochange it of course, so it doesnt work.

Ruth says her favourite aspect of the houseisnt any one thing, but the whole atmosphere:Its just lovely to be in, has such a lovely feel,its light and spacious. Its comfortable, aboveall else. Warm, dry, peaceful, draught free evenwith a door wide open in mid-winter. Whatsnot to like?

There is a particular pleasure for passive houseowners when the weather is nasty outside. Ilove being here in winter, I can sit anywhere,and its always cosy. When I visit friends andfamily their homes always seem dark, coldand damp, and I have to bring slippers andthick sweaters! Even though Ruth opted forthe simplicity (and exposed thermal mass) ofa concrete floor, its never cold, she says.

Everyone who visits likes the style, with thehand-crafted details. Ruth feels that the bespokework that went in to creating her door latches,banister rails and the like has given her some-thing she wouldnt have had with a more hard-edged, interiors magazine style.

Yet, as Mike points out, the sharp and high-tech look isnt easy to pull off. Architects tendto like the crisp modern contemporary look,and we can do it, but the contemporary thingrequires a lot of planning, with tiles cut just so,glass stairs and so on.

Id argue that with a more organic approachlike ours, you actually get a lot of nice effectfor more modest cost. And we find actually peopletend to respond well to a bit of natural stuff,

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so we prefer the handcrafted finish peoplecomment most of all on things like the wobblybalustrading, and wooden door handles.

Being able to finish a building like this is par-ticularly satisfying for Mike: On one hand youcould say that is superficial, but the finish isan important part of the house. I think it givesthe house soul.

SELECTED PROJECT DETAILSClient: Ruth Busbridge Architect: CTT Sustainable ArchitectContractor: Mike Whitfield ConstructionM&E Engineer: Alan Clarke Energy consultant: Elemental SolutionsAirtightness tester: Paul Jennings Cellulose insulation: Warmcel, via PYC InsulationSheep wool insulation: Black Mountain NaturalInsulation Windows & doors: Optiwin, via Green Building Store

Gas boiler: RemehaMVHR: Paul, via Green Building StoreSolar thermal: Llani Solar Hot water cylinders: McDonald EngineersLamps: LocklampLight fittings: Colin Chetwood Low water fixtures: Green Building StoreGreen roofing: Green Roof OptionsSilica paint: Keim Mineral PaintsI-beams: JJI Joists Insurance: Insure GreenFinance: Ecology Building Society

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new build

PROJECT OVERVIEW:

Building type: 129 square metre (TFA) de-tached two-storey timber frame house

Location:Ledbury, Herefordshire

Completion date: June 2012

Budget: 240K

Passive house certification: certified

Space heating demand (PHPP): 14kWh/m2/yr

Heat load (PHPP): 9 W/m2

Primary energy demand (PHPP): 79kWh/m2/yr

Environmental assessment method: none

Airtightness (at 50 Pascals): 0.24ach

Measured energy consumption:74 kWh/m2/yrapprox (August 2012 to August 2013. Conversionfactors: 11kWh/m3 for 385m3 gas and 2.7kWh/kWh for 1989kWh electricity)

Ground floor: 200mm reinforced concreteslab (raft foundation) insulated with 300mmEPS insulation. U-value: 0.113

Timber clad walls: douglas fir horizontalcladding externally, followed inside by 25 x50mm treated battens, Permaforte membrane,22mm wood fibre board, 45x45 outer timberframe with Warmcel, 280mm Warmcel cavitywith Larsen truss ply gusset, 45 x 95 structuraltimber frame with Warmcel, 18mm OSB,Pro Clima DB+ vapour check and airtightmembrane, 45mm service cavity insulatedwith Black Mountain Natuwool (sheep wool)insulation, 28mm double plasterboard andskim. U-value: 0.096

Render clad walls: lime-based render, 40mmSteico board, 45x45 non-structural timberframe with Warmcel, 300mm Warmcel cavitywith Larsen truss ply gusset, 45 x 95 structuraltimber frame with Warmcel, 18mm OSB,Pro Clima DB+ vapour check and airtightmembrane, 45mm service cavity insulatedwith Black Mountain Natuwool (sheep wool)insulation, 28mm double plasterboard andskim. U-value: 0.089

Roof: reclaimed Welsh roof slates externallyfollowed underneath by battening, 22mmSteico board, 45/316/45 timber I-beams withWarmcel, 75mm timber batten with Warmcel,18mm OSB U-value: 0.085

Windows: Optiwin Alphawin alu-clad timbertriple-glazed window. Passive House Insti-tute certified installed window U-value: 0.85

Heating system: Remeha Avanta gas boiler18kW with Stelrad radiators. Five squaremetre Velux solar thermal panels with cylinder:250L Indirect Powerflow 2000 unvented mainspressure system (split 100L Solar, and 150LBoiler). Microbore hot water pipes throughout.

Ventilation: Paul Novus heat recovery ven-tilation system. Passive House Institute cer-tified to have heat recovery rate of 94.4/93%effective heat recovery rate.

Green materials: green roofs on two single-storey extensions. Reclaimed Welsh slates.Cellulose and sheep wool insulation. Keimsilica paint, UK grown timber English oakfloorboards, untreated douglas fir cladding,softwood frame. I-beams from JJI Joists (Scot-land). Locally made doors and door latches.Locally made light fittings. Low energy light-ing throughout (T5 tubes, LEDs, compactfluorescent lights).

(below) metal web floor joists enable the HRV ducting to be run discretely through the house, along withpipes and wires; (bottom) the timber frame walls are insulated with Warmcel cellulose insulation but withNatuwool sheep wool insulation at service voids and window reveals and finished with plywood boxes;(above) building contractor Mike Whitfield outside the house as it nears completion

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For me there was a strong wish with this houseto produce a design that would demonstratethat achieving the passive house standardwas not an impediment to good architecture.Two years ago, at the Better Building conferencein Dublin, one of Irelands leading educatorsof young architects argued that great architectureshould be exempt from energy efficiency reg-ulations, because having to comply would ex-cessively interfere with the expression of hisarchitecture. It is tragic to think that a great ar-chitect believes he cannot accommodate robustdetailing within his artistic objective.

We can only counteract this attitude by proving itwrong. I think it is incumbent on clients anddesigners of passive houses to ensure thatonly the highest standard of design is achievedin passive buildings. A passive house certificateis not a substitute for good a

Passive house plus issue 9 (UK edition)

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