Primrose CI.pdf - Viking House

Photo: Paul Tierney
GIMME
SHELTER
NEW ST VINCENT DE PAUL ECO
HOUSING THRIVES IN TIGHT SPACE
Designing a low energy building when you've got unlimited space is one
thing – but what if you need to make your walls thin to maximise space
on a small site in an architectural conservation area? Lenny Antonelli
visited a new St Vincent De Paul sheltered housing project that fit a lot
of sustainable features on to a small plot in Dublin's north inner city.

Architect John-Barry
Lowe's goal wasn't
exactly simple: design
a low energy
building on a tight
plot in a dense urban
area, but make it
spacious enough
for four people to
live comfortably in
four separate apartments. It was never going
to be an easy task – each apartment was to
have just over 20 square metres of floor space.
Lowe designed the building – on Primrose
St on the northside of Dublin city – for
the St Vincent De Paul Society. The society
manages six such houses around Dublin's
inner city – all are transitional homes for
those making their way from life in homeless
hostels, or on the street, to more permanent
accommodation. In the past these
houses typically had shared bathroom and
kitchen facilities, but the society has started
the process of converting them into separate
self-contained apartments to offer
residents more independence and privacy.
The house that previously occupied the
Primose St site had shared facilities, and
the society was keen to convert it.
Lowe was charged with this task. He decided
to knock the existing building on
the site, a house clad with what he describes
as a "horrible brown tile." "It was
brutal," he says. Low energy building
specialists Viking House set about constructing
a new building from scratch,
starting with new foundations. Viking
House's foundation system is certified by
the Passivhaus Institut, and features 300mm
of expanded polystyrene (EPS) insulation
and precise detailing to prevent cold bridging
between the foundation and the wall. It
boasts a formidable U-value of 0.1 W/m 2 K.
Inside, the house is divided into four separate
units – two up and two down, each designed
for one resident. All are at least dual aspect
– three are triple aspect – and all are
designed to make the most efficient use
of space possible. Though each has a floor
area of just 20 square metres, the apartments
feel much larger, and are easily comfortable
enough for one person to live in.
Unable to use a thicker build because of
the site's constraints, Viking House specified
a timber frame system – manufactured
in Thurles by TMB Timber Frame and
completed by MBC Timber Frame when
TMB sadly fell victim to the downturn –
of about 200mm. From the inside out the
build-up includes plasterboard, 37mm of
cross battening with Rockwool insulation,
taped USB board, a 140mm stud with
Rockwool insulation, 9mm of Panelvent,
a Tyvek membrane, and then a 50mm
cavity. Lowe specified a brick finish for
the front and sides of the build, with
concrete block to the rear. The build-up
has a U-value of 0.23 W/m 2 K. While this
isn't ground-breaking – the building regulations
demand a U-value of 0.27 W/m 2 K
at worst – it’s quite impressive considering
the slender build.
The brick finish is one of the building's
crowning achievements, allowing it to fit
snugly in the surroundings of Dublin's
city centre. The brick works so well that
from outside you'd be forgiven for thinking
the building is much older than it is –
exactly the effect Lowe was going for.
He'd like to have salvaged bricks from the
original building, but removing the brown
tiles would have damaged the brick beneath.
The roof boasts a U-value of 0.97 W/m 2 K
and features 400mm of blown cellulose
insulation, installed by contractor John
Egan of Cellulose Insulation Ltd. Cellulose
typically contains 80 to 85 per cent recycled
newspaper content, and is particularly
effective at maintaining its thermal
performance in high humidity. Because
the building is in an architectural conservation
area, sash windows were essential
to recreate a period look. This meant it
wasn't possible to reach the highest levels
of thermal performance – the double
glazed units have a U-value of 1.7 W/m 2 K
Viking House sealed the house using airtight
tapes from Siga, taping up all junctions
carefully. Taped OSB board in the
walls and roof are the principle element
of the air-tight layer, which stretches across
the ceiling of the ground floor as well as
the first. During blower door tests all of
the units scored between two and three
air changes per hour. As Construct Ireland
went to print a second blower door test
was planned following further sealing work.
The apartments are heated by individual
condensing gas combi boilers, installed
by heating efficiency experts Ecosave.
The Alpha Heating CDC-25C boilers have
a certified efficiency of 90 per cent and
an A rating on the Sedbuk (Seasonal efficiency
of domestic boilers in the UK) database.
The boilers feature a built-in 'seasonality
valve' that automatically adjusts the flow
of domestic hot water based on the temperature
of the incoming main. They feature
temperature and hot water controls
too, while each apartment also has a thermostat
for simple temperature control. Heat
is distributed by radiators upstairs and
an underfloor heating system downstairs.
Each apartment has its own heat recovery
ventilation unit too – an MTD ERV140.
The unit is registered on Sap Appendix Q
and provides a heat recovery efficiency
(below) The new timber-frame building boasts impressive thermal performance despite thin walls being required on the tight plot. The
brick finish is one of the building’s crowning achievements, fitting comfortably in the surroundings of Dublin's north inner city
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The house is divided into four 20 sq. m self-contained apartments, each featuring a bathroom, bedroom (above) and kitchen-cumliving
room (below). Designing the building so four people could live comfortably in four separate apartments was one of the key challenges
for architect John-Barry Lowe; (opposite) a doorway leads from the street to the meeting room at the building's rear
of up to 92 per cent. Lowe designed the
building so most services would run in
the ceiling space above each apartment,
adding to the vertical height of the building
but not the floor area. He considered
using a passive heat ventilation system,
but ruled it out for two reasons: the relative
infancy of the technology, and because
it would have required vertical ducting
that would take up floor space. Installing
community ventilation and heating systems
for the whole building was also
considered, but practical concerns meant
it wasn't feasible – some residents may
potentially be eligible for free electricity
and gas, while others may not, so individual
billing was more convenient. St
Vincent de Paul were also keen for each
resident to have full control over his
own heating system too.

 Building Energy
Rating assessments were carried out on
each of the four apartments – the results
ranged from 155 kWh/m 2 /yr to 173
kWh/m 2 /yr, C1 ratings. This seems disappointing
for a well insulated building,
but there's a simple explanation: because
the stairway and halls outside the apartments
are unheated, they're regarded as
a "cold space" when the BER is calculated.
This means the heating demand is considered
by Deap – the software used to
calculate BERs – to be higher than it actually
is. The internal walls of the apartments
are actually insulated fairly well, with a
U-value of 0.28W/m 2 K and about 100mm
of Rockwool insulation. Having individual
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heating systems in each apartment also
adversely effects the BER. Lowe reckons
that if the building was treated as a single
house and solar thermal panels were
installed, the BER would be a B1 at worst.
Carbon dioxide emissions for the apartments,
as calculated in Deap, are between
30 and 35 kgCO 2 /m 2 /yr. Viking House also
calculated the performance of the building
using the Passive House Planning Package,
the software used to design and test to the
passive standard. The calculation produced
a figure for specific space heating demand
of 56 kWh/m 2 /yr. The windows and exterior
walls were found to be the main sources
of heat loss from the building.
To the house's rear, Viking House built a
15 square metre meeting room with the
same wall construction as the main building.
The room's main feature is a huge glazed
sliding door that runs most of its length.
"That was about natural light and making
the room feel wider," says Lowe. "By having
light at the side of the room and dark
at the ends, it creates the illusion of a larger
space." The room could also potentially
house 20 to 25 people for meetings, so a
big door makes sense for practical reasons
too. The meeting room includes the
same boiler as the main building, but a
different HRV unit – a Vent Axia HR300,
supplied by Lindab. This HRV unit features
a motion sensor, so it only comes
on when the room is occupied.
(below) The stairs and hallways are unheated and thus regarded as a "cold space" when
the BER is calculated - this means the apartments are considered to have a higher heating
demand than they do; (above) a sedum green roof was installed on top of the meeting
room; (p43, top) the meeting room has a large glazed sliding door, designed to
increase natural light and make the room feel wider; (p43, bottom) for conservation reasons,
sash windows were used to recreate the period look
Keeping the meeting building low and
leaving a gap behind the main building
creates a light well that helps to naturally
illuminate the interior of the main
building. The meeting room is also topped
with a sedum green roof, supplied by Moy
Materials and installed by KD Roofing. The
roof features a sedum mat of about 60mm
over 50mm of specially formulated soil.
The motivation for the green roof was
primarily aesthetic - it'll be much more
pleasant for first floor residents in the
main building to look down onto greenery
than a dull grey roof.
Green roofs are becoming increasingly
popular as architects and builders realise
they can satisfy some crucial demands:
they can soak up rainwater in cities with
stressed sewage systems, extend the
lifespan of roof components by protecting
them from sunlight and rainfall, and provide
thermal and acoustic insulation too.
Sedum mats are an example of an extensive
green roof – the shallow variety typically
designed with biodiversity and
aesthetics in mind. Sedum is a type of
herbaceous plant that is tolerant of
drought and requires little maintenance
– generally two visits a year to remove weeds
and apply fertiliser. There are about ten
different species of sedum planted in a
typical mat, and they usually grow to about
six to eight inches in height. Lowe says
he's interested in using intensive green
roofs in future too – these can be up to
300mm deep and provide a medium for
growing food.
The finished Primrose Street building is
both compact and comfortable, and manages
to achieve impressive energy performance
and an authentic period look
in a tight urban space. "I'm very satisfied
with the way it turned out," says Lowe, who
believes the building's efficient use
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of space is one of its triumphs.
"There is an incredible economy in the way
the small building footprint has been designed
in such a compact and efficient
way that the quality of the spaces is actually
improved through excellent daylight
and refined layout of overlapping
functions," he wrote in an email to Construct
Ireland ."This is a much more ecological
and sustainable approach than
designing oversized spaces which can
often be of a poorer quality in terms of
layout, daylight and build standard, while
at the same time commanding more resources
both during their construction
and their operation once occupied. In
many ways bigger is not always better."
Lowe set up his firm, Eden Architects,
five years ago. "I'm definitely as interested
in well functioning buildings as I
am beautiful buildings," he says. "The
buildings that get celebrated look great
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(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 Passivhaus
Institute and eliminates cold bridges between the slab and wall
but people don't care if they work". Lowe
says his designs are based on appropriateness
to site, as well as climate, maintenance
and how the building will be used,
and that Eden's aim is to create spaces
that are warm, well-ventilated, draughtfree
and full of natural light. He's always
had an interest in sustainability. "Before
I ever did architecture, I was doing projects
on solar energy in school."
But the Primrose St building was ultimately
built for St Vincent De Paul – so what do
they think of it? "From our perspective
it's brilliant, there's not an inch of space
wasted," says the society's Eamon Murray.
Indeed, efficient use of space is an
aspect of sustainable building that is
often overlooked. By making better use
of smaller spaces, and utilising clever
design so tight spaces seem bigger than
they actually are, more can be achieved
with less – this means less resources
consumed, and less energy used.
All four apartments at Primrose Street had
just been occupied as Construct Ireland
went to print, so it was still too early to
gauge the new residents' thoughts. But
Murray explains the difference sheltered
housing like this can make to someone
who has been living on the streets: "We
moved one lad into another one of our
houses, I dropped in to talk to him and it
was lashing rain when I met him. I asked
him what he had done for the day and he
said he went from coffee shop to coffee
shop just to stay out of the rain. Then he
suddenly realised – he had his own apartment,
he didn't need to do that any more."
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
SELECTED PROJECT DETAILS
Client: St Vincent De Paul Society
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