Saint léry en

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Social housing without any
heating bills!
Key dates :
Conception : 2009.
Sales completion : April
2010.
Work : April 2010 to May
2011.
A unique developer joined forces with a community housing office to
create a group of four council dwellings in the rural village of Sant-Léry.
The building, insulated with recycled newspapers and wood wool does
not use any heating for the benefit of its residents.
Introduction
Saint Brieuc
Quimper
Vannes
Rennes
St Léry
Saint-Léry
Façade Sud - Photo © Fabienne Briero - Habiozone

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‘To develop eco-friendly housing for
all’ is the motto of Habiozone , the
project developer. When they first
contacted the community housing
office in 2007 to build passive council
houses, the project seemed foolish.
However, people on low income are
the ones who would benefit most
from low energy bills.
To see this project through, it was
necessary to meet the restricted
councilbudgetandtoworkinharmony
with all parties involved, from the
design phase onward. The contractual
commitment to low-consumption
building and passivhaus certifications
Context
has driven the involvement of all
parties. In accordance with passive
construction standards, the chosen
architect designed a compact
building of 282 sq m – 70.5 sq m
per accommodation (with excellent
thermal insulation). The heavily
glazed areas are south-facing, to
take advantage of solar heat. The
insulation is made from eco-friendly
building materials and the building
meets accessibility standards. The
1100 sq m site is sheltered from the
wind and shade.
Plan © Le Garzic Achitecte

3. French-British collective Libnam3
The building was built using light, dry
materials. The floor is entirely made
of wood, on top of a crawlspace.
It has been insulated with a 40 cm
of German-made cellulose fibre
insulation. The finish is made of
marmoleum sitting on 20 mm thick
gypsum board (Fermacell).
The wall structure is made of frames
(Class 2 treated spruce) with 45 x 225
cm posts. It is braced with 16 mm
plywood boards. 22.5 cm of fibre was
blown into the cavity, then covered
with a 60mm wood fibre rain-barrier
(Pavatherm) and Douglas fir cladding
including an air gap.
Building overview
The roof is made of a steel deck on
which 40 mm of polyurethane and
36 cm cellulose fibre are fixed with a
vapour barrier.
The internal walls are covered with
plasterboard or gypsum (Fermacell).
The wooden front doors and the
wood and aluminium triple-glazed
windows come from Alsace (Bieber).
The bay windows are not sliding but
inward opening. Sun shields support
solar panels which power a hot water
storage tank, with electric back up.
The heat exchanger unit made in
Germany (Paul) enables optimal heat
recovery.
Finally, two 5 m³ rain water tanks are
used for the garden and toilets.
Panneaux solaires thermiques- Photo © Fabienne Briero - Habiozone

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Technical focus :
Wooden floor
In order to test the construction
of four dwellings using light/dry
material, the floor is made only of
wood, without a concrete slab or
concrete blocks. 70 linear metres
of glued laminated timber, locally
manufactured by a specialist, have
been laid on 15 foundation pads.
The top of the pads had to be level
to reduce future wedging with
hardwood. As the beams supporting
the floorboards were in contact with
the ventilated crawlspace underneath,
they have been thoroughly treated.
They measure 500 x 200 mm.
Above the suspended beam,
I-shaped joists (320 mm) have been
fixed, braced by OSB boards. This
second layer houses the cellulose
fibre insulation.
Coupe © Le Garzic Achitecte
Barriers and solutions
Theheadoftherealestatefirmwanted
to anticipate the difficulties as much
as possible by fostering collaboration
between the various partners from the

5. French-British collective Libnam5
is unnecessary in a passive house,
the surveyor agreed to restrict the
electrical equipment to cabling and
connection to the switchboard and no
electric storage heating was installed.
On site, the cooperation between
trades was facilitated by creating a
cooperative (Eco-artisans de l’Yvel).
This created a spirit of working
together and feeling responsible for
each other.
As for the residents, they have praised
their houses once they moved in. The
lack of need for heating was not a
fantasy except for the occasional top
up during a cold spell. Nevertheless,
users of a passive building must be
prepared, more than others, to look
Extérieur - Photo © Servane Guihaire - Constructys Bretagne
start. The economic constraints were
overcome by adapting the budget
from the council. The pantry, carport
and solar protection on windows had
to be removed as a consequence.
It was necessary to convince the
insurance company to cover for
building defects. As the housing
councilwasalreadyaclientandowned
a building maintenance service,
the cover was easier to get. The
surveyor also agreed to be involved
in meetings. He was able to help
companies come up with technical
expertise, especially for the building
crawlspace. Regulation makes electric
storage heating compulsory. As it

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after the building. For this reason, a
guide book was given to the tenants.
For example, appliances need to be
of good quality. If the fridge is not
sealed properly in a passive room
which barely cools down, it will over-
consume energy. A cooler room,
separated from the passive part of
the house, would then be beneficial.
Also, it is necessary to ventilate the
room when a large number of people
are in as body heat will act as heating!
Finally, sunshades contribute to
reducing overheating.
Focus : Where are we
going from there ?
The whole experience of building
the council houses at Saint-Léry did
Intérieur - Photo © Fabienne Briero - Habiozone
not meet many obstacles. Media
coverage promoted the outcome.
Tenants are happy. But despite all
this, these experiments have not
developed. Why is that?
Even if the developer believes that eco
construction has grown in the last few
years, he notices that construction
methodshavenotbeenfundamentally
challenged. Many towns and councils
want to put a building or an eco-
neighbourhood in the spotlight, but
few aim for normalization of passive
or eco-friendly housing. Furthermore,
councils are reluctant to identically
reproduce a successful building even
if it is customisable.
Finally, public project management
puts most of the emphasis on time,

7. French-British collective Libnam7
speed, volume and cost, even if
running costs are going to prove more
expensive than in passive buildings.
Focus :
Purchase on future
completion
The real estate programme of the
Courtieux area has been sold on
future completion to the community
housing office. In this type of sales
contract, the purchaser (the housing
office in this case) becomes the
owner of the building only after its
completion. The developer therefore
keeps full control as main contractor
until the end of the build. This has
enabled Habiozone to be relatively
in control of technical decisions and
able to select the trades. In this type
of sale on completion, the developer
is required to provide a financial
guarantee of completion, which
protects the purchaser.
The Domaine des Courtieux obtained
the French certificate of (BBC) (low
consumption building and the label
Passivhaus). It was the first communal
dwelling to be certified passive in
Western France. It also received an
award at the Pyramides d’argent
2012.
A thermography study has been
Performance
Maison passive - Photo © Servane Guihaire - Constructys Bretagne

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Stakeholders
Developer : Habiozone éco-promoteur
(Mauron)
Public housing office : Bretagne Sud Habitat
(Vannes)
Project manager : Le Garzic Architecte
(Rennes)
Contractors cooperative : Les éco-artisans de
l’Yvel (Mauron)
Groundworks : Bergamasco (Ploërmel)
Timber construction : Eurl Briero (Mauron)
Internal walls : Rialet (Mauron)
Plumbing, electricity, ventilation : Thamin
(Mauron)
Decorating, Flooring : Sarl Derval (Taupont)
Bathroom/sinks : Cochet (Mauron)
Link
www.habiozone.fr/Logements-Passivhaus.
html
Costs
Groundwork : £13,935 before tax
Timber structure : £67,480 before tax
Frame : £11,571 before tax
Insulation : £29,099 before tax
Roofing : £10,772 before tax
Joinery : £59,298 before tax
Rendering-Plastering : £21,586 before tax
Electricity : £11,108 before tax
Plumbing : £31,966 before tax
Flooring : £11,589 before tax
Ventilation : £14,813 before tax
Decorating : £13,268 before tax
Cladding : £22,783 before tax
Decking : £8,307 before tax
Total construction cost : £327,575 before tax
equivalent to £1,149 /sq m before tax
Metrology : £15,215 before tax (including
subvention of £11,587 )
Double certification : £2,500 before tax
Airtightness test : £743 before tax
conducted on the building by the CETE (Building technics study centre), which
did not detect any thermal bridging. The ADEME (Agency for the Environment
and Energy) has financially supported the fitting of sensors in the building to
analyse and evaluate its performance in real time. While waiting for the results,
the first reports already show that appliances are the greatest consumer of
electricity. Except during cold spells, the building does not require heating.
Façade Nord - Photo © Servane Guihaire - Constructys Bretagne
Contact
Constructys Bretagne
www.constructys-bretagne.fr