Construct Ireland article - Viking House

Photos: Amy ColleyEnd resultGREEN REFURB & EXTENSION REVIVES END-OF-TERRACE HOUSEIn light of the current economic conditions, an increasing number of Irish people are turningaway from buying new homes, instead deciding to make the most of what they’ve got by extendingand refurbishing. Lenny Antonelli visited one such house nearing completion in Glasnevinthat uses a combination of materials and techniques to aim for highly sustainable results.Gerard and EllenMenezes had littlechoice but to renovatethe end-of-terraceGlasnevinhome they boughtin 2003. “For ourfirst winter here wehad all single-glazedaluminium windowsand there was no insulation at all,” EllenMenezes says. “You could see your breathit was so cold. We’d have the heatinggoing full belt, and our bills were huge.”Space was also an issue for the Menezes’sand their two young children. “Thehouse came with planning permission toextend and we wouldn’t have bought itotherwise. It’s not that big, it was only78 square metres.”The couple are nearing completion of arefurb and extension that has boostedthe building energy rating (BER) of thehouse from a D2 to B1. They receivedthree offers for the upgrade, with themid-priced and winning tender comingfrom green builders Viking House, whoinsulated the house externally and addeda 65 square metre closed-panel timberframe extension. Viking House’s SeamusO’Loughlin is keen to stress that greenextensions needn’t be prohibitively expensive.“For the price of a normal extension,you can get a factory-built passiveextension, lifted over with a crane, thatcan be finished in a few weeks,” he says.Other bidders offered more conventionalupgrades, but for Ellen Menezes the intentionwas always to go green. “That wasalways the plan,” she says. “It’s just what’s

important to us. My sister is a sustainablearchitect, (my interest) probably comesfrom as far back as when my father didbuilding, and we got to see some of thebuilding materials and how they perform.”Having previously dry-lined parts of theirsitting room and kitchen, the Menezes’shad witnessed builders struggle withgreen building materials. “When we gotthe Homatherm (a wood-fibre insulationproduct from Ecological Building Systems)before, our previous builder lookedat us and presumed it must have beenfor the attic. But we said no, it’s for thewalls. He hadn’t worked with the materials.So this time we said we wanted towork with somebody who knew how touse them.”Limerick-based insulation specialists Aerobordsupplied the 100mm of expandedpolystyrene (EPS) insulation added externallyto the front and back of the house,originally built from pre-cast concrete.“We used polystyrene because the wallsweren’t breathable anyway,” O’Loughlinsays. Ellen Menezes admits she wasn’taware of external insulation beforeViking House recommended it. “WhenSeamus mentioned that we could clad onthe outside, it seemed like a brilliant optionbecause the house is so small.”Externally, the EPS 100 was finished witha fibreglass-reinforced cementitious plasterfrom Weber. The refurbished walls werebrought up to a U-value of 0.22 W/m 2 K.An air gap between the polystyrene insulationand original wall allows moistureto dry out. “It allows any moisture that'sbuilt up to be redistributed to areaswhich are drier. If there's a damp patchit'll spread it over a big surface area,”O'Loughlin says. The old attic was insulatedwith cellulose to an average depthof about 400mm, boosting the U-valuefrom 0.35W/m 2 K to 0.2W/m 2 K.Viking House installed a new boiler too –a 90 per cent efficient Ravenheat modulatingcondensing gas combination boiler.Unlike conventional boilers, combinationboilers heat water on demand, so theydon’t need storage tanks and consumeless energy, though they sometimes havea lower flow rate. Underfloor heating isinstalled downstairs in the new extensionand in the new ensuite upstairs,while radiators heat the original house.In partnership with Viking House, MBCTimberframe manufacture the closedpaneltimber frame system used for theMenezes extension in Cahir, County Tipperary.From the inside out, the wallbuildup includes 13mm of Fermacell, a70mm service cavity insulated withblown cellulose, OSB board (taped forair-tightness), 150mm timber studdingwith more cellulose insulation, 80mm ofwood-fibre board, and a breathable mineralplaster supported by fibreglassmesh. It boasts a U-value of 0.13W/m 2 K.Electrical conduits, windows and doorsare all fitted in the factory, and thehouse arrives ready for painting.The roof of the extension has a similarbuildup: 100mm of wood-fibre board onthe outside, OSB on the inside and 250mmof cellulose in between, resulting in a U-value of 0.12W/m 2 K.O'Loughlin stresses that various factorseffect the performance of insulation.“Heat is lost through insulation in threeways – through conductivity, which ismeasured by the lambda value of the insulation,through the insulation density,which is the amount of heat stored withinthe insulation to be given back to the houselater, and through decrement delay, orphase delay, which is the ability of denseinsulation to slow down heat loss and gain.”O'Loughlin says Viking House's combinationof wood-fibre board and cellulose offersa decrement delay of more than twelvehours. “This allows midday heat backinto the building twelve or more hourslater, and dramatically slows down heatloss. The dense insulation also acts as abuffer to balance out heat fluctuation,”he says.O'Loughlin refers to study from DelftUniversity of Technology in the Netherlandsthat examined two similar houses,each with a roof U-value of 0.21W/m 2 K –one insulated with lightweight fibreglassand the other with denser cellulose. Bothwere oriented to the south and remainedunheated during the study period, throughoutwhich outdoor temperatures fluctuatedby 25 o C. While the temperature inthe fibreglass-insulated house varied by13 o C, it fluctuated by just 3 o C in the cellulose-insulatedhouse. When the temperatureoutside dropped to 10 o C, theinside of the fiberglass-insulated housemeasured 14 o C, yet it was 18 o C insidethe cellulose-insulated house.“So the dense insulation kept the housefour degrees warmer than the lightweightinsulation with a similar U-value,”O'Loughlin says. “If you wanted to getthe temperature fluctuation similar inboth houses then all you would have todo is put a 50mm layer of wood-fibreboard on top of the 200mm of fibreglass.Every 10mm of wood-fibre board givesyou an hour extra of decrement delay.”O'Loughlin offers an anecdote to illustratethe importance of dense insulation materials.“My friend stays in his log cabin inSweden for a few weeks every winter. Heheats the house with a log stove that tendsto go out at about 2am. Often it gets ascold as minus 20-25 o C at night, but thelog cabin loses heat relatively slowly andit's typically 10-12 o C inside the cabin inthe morning, 15-20 o C warmer than outside.First thing in the morning, he lightsthe stove again.”O’Loughlin continues: “While he wastelling me this story, I was thinking of (below) 100mm of expanded polystyrene (EPS) insulation was installed externally on the front and back of the end-of-terrace house, giving therefurbished walls a U-value of 0.22 W/m 2 K. The EPS was finished externally with a fibreglass-reinforced cementitious render from WeberCI 43

(above) Construct Ireland journalist Lenny Antonelli (left) speaks to Viking House’s Seamus O’Loughlin (right) on site in Glasnevinthe winter nights I spent in a caravan inIreland with a gas heater. The temperatureinside the caravan would reach theexternal temperature of maybe 8-10 o C inunder an hour after the stove was putout, even though when you calculate it,the caravan has a better U-value.” Heconcludes: “In order to buffer temperaturefluctuation, materials need to beheavy and have a good U-value. Woodfibre,poroton, aerated concrete blocksand timber are all good products forthis.” O’Loughlin is keen to stress anotheradvantage materials like timberand poroton have over concrete. “Becausethey have a good U-value, the heatdoesn't transmit through the material, sothe outer layer stays warm. If your wall is15 o C you'll need to heat the room to 25 o Cto feel comfortable, but if the wall surfaceis 19 o C, you'll only need to heat theroom to 20 o C.”The extension at Glasnevin also featuresViking House’s patented foundation system,which includes three layers of EPS100 insulation (300 mm altogether).O’Loughlin says the foundation needsless than a third of the concrete of conventionalbuild, and requires just onepour. “The foundation system eliminatesthe cold bridge between the wall and thefloor,” he says, referring to the cold bridgein most foundations where the walls cutthrough the floor insulation and meet thefoundation.The foundation system boasts a U-valueof 0.107 W/m 2 K, and Viking House claimit reduces to 16 per cent the amount ofheat lost to the ground from an underfloorheating system, as opposed to afigure of 65 per cent which Viking Houseclaim is typical for conventional Irish build.Rationel supplied the extension’s double-glazedwindows – the same units installedin the original house prior toViking House coming on site. O’Loughlinwould have preferred triple glazing inthe extension, but the Menezes’s werekeen for it to retain the same look as therest of the house.A blower door test in the extension produceda result of 0.75 air changes perhour (ACH) – slightly short of the 0.6ACHpassive house standard. “We just built itthe way we always do, and we were expectinga good result,” O’Loughlin says.“We put the OSB board on the inside andtaped all the joints with Siga tapes, andtaped up the inside of the roof. Whenyou do that, it’s easy to get close to passiveair-tightness levels.”The original blower door test produced aresult of 0.9ACH. “There was some tapingdone at the floor junction and someservices were taped up after that,” saysArchie O’Donnell of Integrated Energy,who tested the house. Integrated Energyoffer a range of low energy and passiveplanning & design services. “We want toget down to 0.6 and we’re confident wecan do that.” The older part of the buildingscored 1.8ACH, and further sealingwork is planned there.O’Donnell also tested the house usingthe Passive House Planning Package(PHPP) software. Even when not buildingto passive standards, O’Donnell seesPHPP as a useful design tool. “It’s an excellentpackage to use as a designer. Itdoesn’t cost you a penny extra to turnyour house towards the sun, and to openup the southern windows,” he says. “Itcan be more useful as a design tool becauseof how it deals with issues likeshading from trees and neighbouringbuildings. And it’s much more detailedin terms of windows and window frames.If you’re looking for a low energy buildingit’s the tool to use.”O’Donnell says he gets regular enquiriesfrom self-builders with planning permissionwho are keen to go passive, but stressesthat it’s more expensive to reach the passivestandard if it wasn’t planned in theoriginal design. “It’s very expensive anddifficult to bolt on solutions.”O’Donnell wonders if a separate passivestandard should be introduced for theupgrade of existing buildings. “It reallyseems that to get an existing building downto passive house levels, you’d almost beas well to take it down and build again.There are some areas where you just won’tbe able to get rid of the cold bridges.”O’Donnell calculated the BER for the CI 45

(above) The closed-panel timber frame extension houses a new en suite bedroom upstairs; (below) to maintain a similar appearence,the same double-glazed windows were installed in the two-storey extension, seen here at right, as were previously fitted in the originalhouse; (p49, top) cellulose insulation was installed in the original attic to an average depth of 400mm, while (bottom) a 90 percent efficient Ravenheat modulating condensing gas combi boiler was also installedupgraded house as a B1 – 95 kWh/m 2 /yrspecifically, and a vast improvement onthe D2 (290 kWh/m 2 /yr) he estimates theoriginal house as having. He stresses,however, that a difficulty in finding relevantinformation meant various assumptionshad to be made about the house priorto upgrade.While the results are clearly impressive,further work is planned that should getthe house up to an A3. As Construct Irelandwent to press, Viking House was setto install 15 square metres of solar panelson the south-facing roof of the extensionwith an accompanying 6,000 litrebuffer tank in the garden. Why such amassive system? To satisfy most of thehouse’s hot water and space heating demand.O’Loughlin reckons that by combiningan oversized array of evacuatedtubes with a new low-temperature underfloorheating system in the old part ofthe house, he can significantly reduce theMenezes’ reliance on gas.O’Loughlin will also install breathingwindows – a type of local heat recoveryventilation (HRV) unit – in the kitchenand bathroom. The breathing windowneeds no air ducts, and features two fansthat draw fresh air into the house whileexpelling stale air. The separated airstreams are then guided through a heatexchanger and discharged (the stale airto the outside, the fresh air to the inside).The unit automatically switches on whenCO 2 or water vapour reach more than 500parts per million. “It can even be CI 47

washed in a dishwasher,” O’Loughlin says.The internal kitchen wall that adjoins theneighbouring house – a major point of coldbridging – will be dry-lined with 80mmof wood-fibre board, and the original doorswill also be replaced with passive-standardGerman doors. “It would be silly not todo it (get new doors) because we’ve got awell insulated house and then this corridorof wind coming through the door,” EllenMenezes says. 300mm of polystyrene insulationwill also be added under the floorof the old house.Seamus O’Loughlin expects the plannedimprovements to get the house comfortablyinto the A3 bracket, but Ellen Menezesis nonetheless happy as things stand.“The house is never chilly any more,” shesays. “It’s comfortable all the time. Mymum used to hate coming up here becauseit’s such a cold house. But after she sawthe renovation she went back home andstraight away found out about gettingcavity wall insulation. She got the pearlbeads done right away, and it’s made adifference in her house too.”SELECTED PROJECT DETAILSClients: Gerard and Ellen MenezesMain contractor: Viking HouseTimber frame: MBCEnergy consultancy: Integrated EnergyExternal insulation: AerobordExternal render: WeberWindows: RationelAir-tightness products: SigaCombi boiler: RavenheatCI 49