Une maison passive en bois de pays pour un couple d’anciens agriculteurs.

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A passive house made of local
wood for a retired farming
couple.
Key dates
Project planning : since
2004.
Design phase : 2010/2011.
Build : February 2012 to 1st
half of 2014.
Once they had retired, Bernard and Viviane wanted a new house. They
wanted it to be comfortable but also self-sufficient in energy (without
the need for heating) to avoid dependency on fossil fuels, as they were
convinced that prices would go up.
They therefore used trees from their garden for the build and insulated
it with recycled newspapers (cellulose fibre insulation). The whole build
was contracted to local craftsmen.
Introduction
Saint Brieuc
Quimper
Vannes
Rennes
Rostrenen
Coatleven
South facade - Photo © Servane Guihaire - Constructys Bretagne

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Context
As well as living in a « no heating »
home, the owners were determined
to use wood from the site for the
frame and to use the skills of local
tradesmen. They also wanted their
house to be future-proof, in case
of reduced mobility in their older
years.
Architect Christophe Gauffeny,
supported by the Thermal Office,
imagined a modular building with
a passive core of 120 sq m (for 211
sq m of total area) South / South
West facing. This is surrounded
by annexes : with either low
consumption or non-insulated
rooms in buffer zones (utility room,
garage, indoor garden etc.).
In the passive part of the building,
no heating system was installed
apart from the heat exchanger.
Wood from the farm was used in
the bungalow structure, on a 2000
sq m plot on the outskirts of a town
of 3400 inhabitants.
Building overview
The timber frame rests on concrete
blocks and a concrete foundation,
on a 60 cm crawlspace with an anti-
radon membrane.
The I-beams (German brand Steico),
thanks to a potential length of 13 m,
enable continuity between the attic
and the crawlspace, thus eliminating
Plan © Christophe Gauffeny
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3. French-British collective Libnam3
thermal bridges between the walls
and the floor.
The outer shell is insulated with
blown cellulose fibre by Isocell (22
cm in the walls, 32 cm in the floor
and 36 cm in the roof) and wool
insulation (for partition walls) and is
clad with fibre boards permeable to
water vapour (35 mm Pavatex).
Many timber posts have been
made from local timber. The outer
windows (made by Menuiserie
André), certified by the Passive
House Institute in Darmstadt, are
triple glazed. Jambs and frames
are kept to a minimum to reduce
thermal loss (only the glazing is
visible from the outside).
Heating is provided naturally, by
the sun and human activity. A heat
exchanger (by Danish company
Nilan) optimises the recycling of the
exiting air (80% return) in order to
heat the air inside as well as heating
the hot water. Its position on the
first floor enables an optimal layout
of cables from the underfloor to the
roof.
Floor structure : concrete blocks
and slab – protection membrane
– I-beams with cellulose fibre – 16
mm bracing – vapour barrier – joists
Timber frame - Photo © Christophe de Quelen - Menuiserie de Quelen

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Technical focus :
Farm wood
In this building, the use of wood is
predominant as it covers 20 to 25
m3 of the space. The use of metal
was reduced as much as possible,
even the partition wall structure is
made of wood.
– local oak floorboard.
Outside wall structure : Douglas fir
cladding or plaster board (BA13) –
5cm gap (for ducts) – bracing panels
– 35 mm Pavatex (glued wood fibre
boards) – 27 mm battens – Douglas
fir cladding.
Roof structure : BA13 plasterboards
– battens – 5 cm gap – vapour
Barrier – 8 mm bracing – I beams
and cellulose fibre – 12 mm OSB
boards – rain barrier – 6x4 rafters –
poplar battens – hessian – zinc.
The wood from the contractors’
farm, comes from oak, cypress and
Sitka spruce. The timber was cut
to be used for beams, panelling,
bracing, battens and floorboards.
The wood was cut on site using a
mobile sawmill. It was then dried
in a warehouse and stored onsite
before being engineered in the
Menuiserie de Quelen workshop.
The owner followed the work on his
wood in the workshop to observe
the different steps of fabrication.
The finish is immaculate as the
timber was knotty – therefore no
two floorboards are identical.
In West central Brittany, a short
chain of construction timber supply
is currently developing in order to
optimise the use of local wood.
Buying-in-bulk schemes are being
set up.
Wood sawing - Photo © Christophe de Quelen - Menuiserie de Quelen

5. French-British collective Libnam5
Barriers and solutions
Planning regulations required the
building to face the road rather
than south. It was necessary to raise
the energy performance objective
with the planning department to
overcome this obstacle.
During groundwork, workers were
faced with the problem of bedrock
close to the surface. The crawlspace
was therefore limited to a 60 cm
gap and the idea of a well had to be
abandoned.
During the building phase, the frame
manager facilitated communication
between trades thanks to his
experience and his position as
Chairman of the ECOB association,
which coordinates 25 members
interested in Eco construction, 15
of whom are craftsmen. Several
companies involved in the building
process were also members.
The building process benefited from
the input of Conseil d’Architecture,
d’Urbanisme et de l’Environnement
des Côtes d’Armor, a local
architecture advising bureau (CAUE
22 - www.caue22.fr). Also, a huge
temporary “Eco-Dome”, a sort of
hot air balloon tunnel, inflated with
huge fans, was installed on site.
This enabled builders to continue
working regardless of the bad
weather (http://domedebretagne.
com/ ).
On the technical side, passive joinery
was a particular focus. Because
of really thin jambs and window
frames, it was preferable to fit the
windows from the outside.
At the time, it proved difficult
Wooden floor - Photo © Servane Guihaire - Constructys Bretagne

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to source passive doors without
doorsteps which constrain the
mobility of wheelchair users.
Nilan was the obvious choice for
heat exchangers as it is the only
4 in 1 device (heat exchanger, air
and water heating and cooling
system all in 1), endorsed in France
(Certification number V RT2012)
and by the PassivHaus Institute.
From a financial point of view,
focusing on the “passive” side of the
core of the house, whilst providing
continuity for the roof between
the passive side and the annexes
proved to be good value for money.
The architectural design is therefore
simplified, while the annexes soften
the «cuboid shape» impression.
The use of local timber, crafted in a
traditional manner, didn’t add to the
final cost.
From a regulation point of view, it
is compulsory to install a heating
source, even in a passive house,
despite the lack of use.
Also, regulations do not
systematically take into account
the imperative of enabling water
vapour movement along the
walls. For example, OSB boards
are compulsory in the outer shell
whilst their water vapour resistance
is relatively high (bringing a risk of
condensation).
The insurer agreed to provide
insurance cover to the carpenter-
joiner if he provided order receipts
Installation of windows - Photo © Christophe de Quelen - Menuiserie de Quelen

7. French-British collective Libnam7
and a building material list during
their annual meeting.
This build was however his first
passive house. He had to undertake
several training courses, joinery
by the menuiserie André, training
at the Energy-Saving building
methods Institute (Formations
aux Economies d’Energies dans
le BATiment FEE BAT), resistance
material, air tightness (www.
averti-expertises.com), cellulose
fibre insulation (Cellaouate - www.
cellaouate.com and Soprema) and
bioclimatic design.
It proved difficult to identify a
competent installer for the heat
exchanger for this build.
The passive core of the house relies
essentially on the heat from the sun
and human activity to keep it warm.
Eventually, in the middle of winter,
depending on the occupation of the
house, a slight heating of the habitat
can be proved useful (a towel drier
would be enough).
Thanks to the heat exchanger, the
heating consumption does not
exceed 14 kWh/year/sq m
The main contractors were not
aiming for an official certification,
but the PHPP (Passive House
Planning Package), awarded in
France by «La Maison Passive
Service», provided guidance on the
design throughout the build.
Performance
Eco-dôme - Photo © Christophe de Quelen - Dôme de Bretagne

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Stakeholders
Main contractors : Bernard and Viviane
Coatleven
Project manager : Christophe Gauffeny
(Design, planning, planning permit
application)
Thermal survey : Passiflore Conseil
(Lannion)
Masonry : CKB (Rostrenen)
Carpentry, joinery, insulation : Menuiserie
de Quelen (Locarn)
Roofing : Ets Glou (Rostrenen)
Plumbing - electricity : Entreprise Goaziou
(Rostrenen)
Heat exchanger : ATS (La Méaugon)
Finishing touches : done by the owners
with traders’ help
Mobile sawmill : Letur (Sizun)
Advise bureau : CAUE 22 (Saint-Brieuc)
Eco-dome : Dôme de Bretagne (Locarn)
Costs
Plot : £30,595
Project managing : £10,786
Thermal survey : £742
Ground survey : £235
Groundwork : £3,133
Masonry : £12,504
Carpentry, joinery, insulation : £134,089
Plumbing - electricity : £10,191
Heat exchanger : £18,000
Wood cutting and drying : £4,119
Plastering : £1,275
Roofing : £13,499
Miscellaneous : £5,534
Total build cost : £214,107 after tax
Total per sq m : £1,014
Integration © Christophe Gauffeny
Contact
Constructys Bretagne
www.constructys-bretagne.fr