GIMMESHELTER

NEW ST VINCENT DE PAUL ECOHOUSING THRIVES IN TIGHT SPACEDesigning a low energy building when you've got unlimited space is onething – but what if you need to make your walls thin to maximise spaceon a small site in an architectural conservation area? Lenny Antonellivisited a new St Vincent De Paul sheltered housing project that fit a lotof sustainable features on to a small plot in Dublin's north inner city.

Photo

: Pa

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Architect John-BarryLowe's goal wasn'texactly simple: de-sign a low energybuilding on a tightplot in a dense urbanarea, but make itspacious enoughfor four people tolive comfortably in

four separate apartments. It was never goingto be an easy task – each apartment was tohave just over 20 square metres of floor space.

Lowe designed the building – on PrimroseSt on the northside of Dublin city – forthe St Vincent De Paul Society. The soci-ety manages six such houses around Dublin'sinner city – all are transitional homes forthose making their way from life in homelesshostels, or on the street, to more perma-nent accommodation. In the past thesehouses typically had shared bathroom andkitchen facilities, but the society has startedthe process of converting them into sep-arate self-contained apartments to offerresidents more independence and privacy.The house that previously occupied thePrimose St site had shared facilities, andthe society was keen to convert it.

Lowe was charged with this task. He de-cided to knock the existing building onthe site, a house clad with what he de-scribes as a "horrible brown tile." "It wasbrutal," he says. Low energy buildingspecialists Viking House set about con-structing a new building from scratch,starting with new foundations. VikingHouse's foundation system is certified bythe Passivhaus Institut, and features 300mmof expanded polystyrene (EPS) insulationand precise detailing to prevent cold bridgingbetween the foundation and the wall. Itboasts a formidable U-value of 0.1 W/m2K.

Inside, the house is divided into four separateunits – two up and two down, each designedfor one resident. All are at least dual as-pect – three are triple aspect – and all aredesigned to make the most efficient useof space possible. Though each has a floorarea of just 20 square metres, the apartmentsfeel much larger, and are easily comfortableenough for one person to live in.

Unable to use a thicker build because ofthe site's constraints, Viking House spec-ified a timber frame system – manufac-tured in Thurles by TMB Timber Frame andcompleted by MBC Timber Frame whenTMB sadly fell victim to the downturn –of about 200mm. From the inside out thebuild-up includes plasterboard, 37mm ofcross battening with Rockwool insulation,taped USB board, a 140mm stud withRockwool insulation, 9mm of Panelvent,a Tyvek membrane, and then a 50mmcavity. Lowe specified a brick finish forthe front and sides of the build, withconcrete block to the rear. The build-uphas a U-value of 0.23 W/m2K. While thisisn't ground-breaking – the building reg-ulations demand a U-value of 0.27 W/m2Kat worst – it’s quite impressive consider-ing the slender build.

The brick finish is one of the building'scrowning achievements, allowing it to fitsnugly in the surroundings of Dublin'scity centre. The brick works so well thatfrom outside you'd be forgiven for think-ing the building is much older than it is –exactly the effect Lowe was going for.He'd like to have salvaged bricks from theoriginal building, but removing the browntiles would have damaged the brick beneath.

The roof boasts a U-value of 0.97 W/m2Kand features 400mm of blown celluloseinsulation, installed by contractor John

Egan of Cellulose Insulation Ltd. Cellulosetypically contains 80 to 85 per cent recy-cled newspaper content, and is particu-larly effective at maintaining its thermalperformance in high humidity. Becausethe building is in an architectural conser-vation area, sash windows were essentialto recreate a period look. This meant itwasn't possible to reach the highest lev-els of thermal performance – the doubleglazed units have a U-value of 1.7 W/m2K

Viking House sealed the house using air-tight tapes from Siga, taping up all junc-tions carefully. Taped OSB board in thewalls and roof are the principle elementof the air-tight layer, which stretches acrossthe ceiling of the ground floor as well asthe first. During blower door tests all ofthe units scored between two and threeair changes per hour. As Construct Irelandwent to print a second blower door testwas planned following further sealing work.

The apartments are heated by individualcondensing gas combi boilers, installedby heating efficiency experts Ecosave.The Alpha Heating CDC-25C boilers havea certified efficiency of 90 per cent andan A rating on the Sedbuk (Seasonal effi-ciency of domestic boilers in the UK) database.The boilers feature a built-in 'seasonalityvalve' that automatically adjusts the flowof domestic hot water based on the tem-perature of the incoming main. They fea-ture temperature and hot water controlstoo, while each apartment also has a thermo-stat for simple temperature control. Heatis distributed by radiators upstairs andan underfloor heating system downstairs.

Each apartment has its own heat recoveryventilation unit too – an MTD ERV140.The unit is registered on Sap Appendix Qand provides a heat recovery efficiency

(below) The new timber-frame building boasts impressive thermal performance despite thin walls being required on the tight plot. Thebrick finish is one of the building’s crowning achievements, fitting comfortably in the surroundings of Dublin's north inner city

The house is divided into four 20 sq. m self-contained apartments, each featuring a bathroom, bedroom (above) and kitchen-cum-living room (below). Designing the building so four people could live comfortably in four separate apartments was one of the key chal-lenges for architect John-Barry Lowe; (opposite) a doorway leads from the street to the meeting room at the building's rear

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of up to 92 per cent. Lowe designed thebuilding so most services would run inthe ceiling space above each apartment,adding to the vertical height of the build-ing but not the floor area. He consideredusing a passive heat ventilation system,but ruled it out for two reasons: the rela-tive infancy of the technology, and becauseit would have required vertical ductingthat would take up floor space. Installingcommunity ventilation and heating sys-tems for the whole building was also

considered, but practical concerns meantit wasn't feasible – some residents maypotentially be eligible for free electricityand gas, while others may not, so indi-vidual billing was more convenient. StVincent de Paul were also keen for eachresident to have full control over hisown heating system too. Building EnergyRating assessments were carried out oneach of the four apartments – the resultsranged from 155 kWh/m2/yr to 173kWh/m2/yr, C1 ratings. This seems dis-

appointing for a well insulated building,but there's a simple explanation: becausethe stairway and halls outside the apart-ments are unheated, they're regarded asa "cold space" when the BER is calculated.This means the heating demand is con-sidered by Deap – the software used tocalculate BERs – to be higher than it actuallyis. The internal walls of the apartmentsare actually insulated fairly well, with aU-value of 0.28W/m2K and about 100mmof Rockwool insulation. Having individual

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heating systems in each apartment alsoadversely effects the BER. Lowe reckonsthat if the building was treated as a sin-gle house and solar thermal panels wereinstalled, the BER would be a B1 at worst.

Carbon dioxide emissions for the apart-ments, as calculated in Deap, are between30 and 35 kgCO2/m2/yr. Viking House alsocalculated the performance of the build-ing using the Passive House Planning Package,the software used to design and test to thepassive standard. The calculation produceda figure for specific space heating demandof 56 kWh/m2/yr. The windows and exte-rior walls were found to be the main sourcesof heat loss from the building.

To the house's rear, Viking House built a15 square metre meeting room with thesame wall construction as the main building.The room's main feature is a huge glazedsliding door that runs most of its length."That was about natural light and makingthe room feel wider," says Lowe. "By hav-ing light at the side of the room and darkat the ends, it creates the illusion of a largerspace." The room could also potentiallyhouse 20 to 25 people for meetings, so abig door makes sense for practical rea-sons too. The meeting room includes thesame boiler as the main building, but adifferent HRV unit – a Vent Axia HR300,supplied by Lindab. This HRV unit fea-tures a motion sensor, so it only comeson when the room is occupied.

Keeping the meeting building low andleaving a gap behind the main buildingcreates a light well that helps to natu-rally illuminate the interior of the mainbuilding. The meeting room is also toppedwith a sedum green roof, supplied by MoyMaterials and installed by KD Roofing. Theroof features a sedum mat of about 60mmover 50mm of specially formulated soil.

The motivation for the green roof wasprimarily aesthetic - it'll be much morepleasant for first floor residents in themain building to look down onto green-ery than a dull grey roof.

Green roofs are becoming increasinglypopular as architects and builders realisethey can satisfy some crucial demands:they can soak up rainwater in cities withstressed sewage systems, extend thelifespan of roof components by protectingthem from sunlight and rainfall, and pro-vide thermal and acoustic insulation too.

Sedum mats are an example of an exten-sive green roof – the shallow variety typ-ically designed with biodiversity andaesthetics in mind. Sedum is a type ofherbaceous plant that is tolerant ofdrought and requires little maintenance– generally two visits a year to remove weedsand apply fertiliser. There are about tendifferent species of sedum planted in atypical mat, and they usually grow to aboutsix to eight inches in height. Lowe sayshe's interested in using intensive greenroofs in future too – these can be up to300mm deep and provide a medium forgrowing food.

The finished Primrose Street building isboth compact and comfortable, and man-ages to achieve impressive energy per-formance and an authentic period lookin a tight urban space. "I'm very satisfiedwith the way it turned out," says Lowe, whobelieves the building's efficient use

(below) The stairs and hallways are unheated and thus regarded as a "cold space" whenthe BER is calculated - this means the apartments are considered to have a higher heat-ing demand than they do; (above) a sedum green roof was installed on top of the meet-ing room; (p43, top) the meeting room has a large glazed sliding door, designed toincrease natural light and make the room feel wider; (p43, bottom) for conservation rea-sons, sash windows were used to recreate the period look

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of space is one of its triumphs.

"There is an incredible economy in the waythe small building footprint has been de-signed in such a compact and efficientway that the quality of the spaces is ac-tually improved through excellent day-light and refined layout of overlappingfunctions," he wrote in an email to Con-struct Ireland ."This is a much more eco-logical and sustainable approach thandesigning oversized spaces which canoften be of a poorer quality in terms oflayout, daylight and build standard, whileat the same time commanding more re-sources both during their constructionand their operation once occupied. Inmany ways bigger is not always better."

Lowe set up his firm, Eden Architects,five years ago. "I'm definitely as inter-ested in well functioning buildings as Iam beautiful buildings," he says. "Thebuildings that get celebrated look great

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but people don't care if they work". Lowesays his designs are based on appropri-ateness to site, as well as climate, main-tenance and how the building will be used,and that Eden's aim is to create spacesthat are warm, well-ventilated, draught-free and full of natural light. He's alwayshad an interest in sustainability. "BeforeI ever did architecture, I was doing proj-ects on solar energy in school."

But the Primrose St building was ultimatelybuilt for St Vincent De Paul – so what dothey think of it? "From our perspectiveit's brilliant, there's not an inch of spacewasted," says the society's Eamon Mur-ray. Indeed, efficient use of space is anaspect of sustainable building that isoften overlooked. By making better useof smaller spaces, and utilising cleverdesign so tight spaces seem bigger thanthey actually are, more can be achievedwith less – this means less resourcesconsumed, and less energy used.

All four apartments at Primrose Street hadjust been occupied as Construct Irelandwent to print, so it was still too early togauge the new residents' thoughts. ButMurray explains the difference shelteredhousing like this can make to someonewho has been living on the streets: "Wemoved one lad into another one of ourhouses, I dropped in to talk to him and itwas lashing rain when I met him. I askedhim what he had done for the day and hesaid he went from coffee shop to coffeeshop just to stay out of the rain. Then hesuddenly realised – he had his own apartment,he didn't need to do that any more."

SELECTED PROJECT DETAILS

Client: St Vincent De Paul Society

Architects: Eden Architects

Main contractor: Viking House

Mechanical contractor: Ecosave

Timber frame: MBC Timber Frame

Sheathing board: Ecological Building Systems

Wall insulation: Rockwool

Roof insulation: Cellulose Insulation

Air-tightness tapes: Siga

Windows & doors: Vrogum

Combi boilers: Euro Heating & Plumbing Supplies

Apartment HRV systems: MTD

Meeting room HRV systems: Lindab

Bricks: Ibstock

Green roof: KD Roofing/Moy Materials

Apartment flooring: Trunk Flooring

Meeting room flooring: Terrazzo Flooring

(above) The existing building, clad in unsightly brown tiles, before it was demolished. "It was brutal," architect John-Barry Lowe says;(below) Viking House installed a new foundation system with 300mm of polystyrene insulation. The system is certified by the Pas-sivhaus Institute and eliminates cold bridges between the slab and wall