The project involved renovating an old rectory into an elementary school, maintaining the original architectural identity. The architect designed an extension within the limits of the existing courtyard and garden. Local materials like stone, wood, lime-hemp blocks and renders were used to give a contemporary feel while respecting the heritage of the area. The renovated building achieved an air permeability rate of 7.67 vol/h, higher than targeted due to openings needed for accessibility, and is expected to reduce CO2 emissions significantly compared to the previous heating system.

1. 28
The restoration of an old rectory
into a public elementary school.
Key dates
Original Construction :
before 1948
Design : 2012 (01/2012 –
01/2013)
Renovation, extension :
01/2013 – 02/2014
The project owner wished to renovate the ancient rectory whilst keeping
its architectural identity. The architect was given the objective of designing
an efficient project using breathable materials for the renovation.
Introduction
Saint Brieuc
Quimper
Vannes
Rennes
Saint Marc
le Blanc
«Le Picaou»
Overview - Photo © Pays de Fougères

2. www.libnam.eu 2
Context
From the architectural point of view :
a courtyard with its own garden
surrounded the old rectory. The
architect chose to stay within these
limits when designing the extension
to the rectory. Granite was chosen
for the façade to maintain the
character of the place. The wooden
cladding and the glass roof give a
contemporary touch to the building
as a whole.
According to the project owner, ‘the
buildings within the town-centre
have a harmonious architectural
style, which also applies to the
rectory’. The heritage development,
together with an architectural
extension consistent with the history
of the area ensures the link to the
town-centre. In addition, pedestrian
paths allowed all municipal services
to be linked. This project allows the
regrouping of the school, school
restaurant, library, and sports hall.
It was given the label of Eco-FAUR*
* Eco-FAUR is recognition and funding
from the Regional Council of Brittany
for boroughs who opt for sustainable
development objectives in their projects.
Plan © Pays de Fougères
N

3. French-British collective Libnam3
Building overview
The project can be split into two
parts: firstly, the renovation of the
stone masonry and earth section of
the original building, and secondly
the new construction using less
eco materials - concrete blocks and
stone. We will focus mainly on the
renovation.
The project owner wanted a high
performance, low environmental
impact project. The architectural
project maximised the use of local
materials (stone and wood), eco-
sourced materials (lime-hemp
blocks, lime-hemp render, earth,
lime and sand), as well as recycled
material; using the granite stones of
the demolished surrounding wall,
and reusing wood from the old
wooden frame.
A workshop was created for the
building using lime-hemp blocks,
and the interior wall was finished
using lime, sand and earth render.
This also involved the repairs of
exterior joints using a lime mortar
made by Weber. This project was
supervised by Etudes ET Chantiers.
The heating system chosen was
a 36 kW vertical ground to water
geothermal heat pump.
A twin / dual network for ventilation
was put in place with a single flow
controlled mechanical ventilation
system managed by a CO2 sensor
and a movement sensor in the
toilets, and a dual flow controlled
mechanical ventilation system for
the rest of the areas. Particular
attention was given to the quality
of the finishing materials to ensure
good air quality (“Ecolabel” paint,
earth render).
Structure - Photo © Pays de Fougères
Earth plaster - Photo © études ET chantiers

4. www.libnam.eu 4
Technical Focus :
« chanvribloc »
For this project, the owner opted to
use hemp blocks from the supplier
CHANVRIBLOC. It is an eco-sourced
material made of hemp «straw»
and hydraulic lime. The blocks are
made in Isère (La Mure region)
and sourced in the Haute-Saône
and l’Aube regions. This focus will
concentrate on two elements: firstly,
the building constraints related to
seismic regulations, and secondly
the different renders (earth, lime-
sand, and lime-hemp).
Two types of blocks were used on
site : 10 cm blocks for the south wall
and 20 cm blocks for the north wall.
The supervising officer, a Chartered
building surveyor, imposed an open
void of at least 5 cm between the
wall of the original stone and the
concrete structure built inside the
building, concrete slab included
(see picture). The insulation of loose
hemp, originally specified, could
not be used because of the seismic
regulations mentioned earlier.
However, the thermal performance
is not affected by this change
in materials. The project owner
opted to screw the blocks onto a
smooth wooden base, following the
manufacturers’ recommendations.
In an effort to maximise the
characteristics of the hemp blocks,
natural renders were used : earth,
lime-sand, and lime-hemp. These
were an industrially produced
render with an earth finish (Argilus),
handcrafted lime-sand and lime-
hemp renders. In fact the sub-soil
of the region of Saint Marc le Blanc
does not have earth easily usable
for producing handcrafted earth
renders.
Lime/hemp block - Photo © Chanvribloc
Interior plaster - Photo © Servane Guihaire - Constructys Bretagne

5. French-British collective Libnam5
Barriers and solutions
As for the organizational and
relational side of things the site
ran rather smoothly, thanks to the
omnipresence of the project owner.
He was able to be very reactive and
make himself available whenever
needed.
The establishment of the insertion
workshop / integration project, of
Etudes ET Chantiers, allowed the
world of integration to confront the
world of business, both working
under different regulations. This
required the project owner, the
companies present, and the
«integration teams» to deal with
the constraints of each person and
organization.
The supervising officer
(Chartered building surveyor) was
uncompromising on the application
of seismic regulations, which made
the building of the hemp blocks and
work on air tightness much more
complex.
The Pays de Fougères offered work
support to ensure the smooth
running of the site, notably
concerning the air tightness work.
This collective involvement was very
positive and allowed the site to run
fluidly.
The application of the lime-hemp
and renders was entrusted to
Etudes ET Chantiers (integration
project management and vocational
training agency). Two groups of
between eight and ten people
were trained via work experience
and their instructor and given
theoretical and practical training by
the use of modules on «insulating
and finishing with render» (earth,
lime-sand, lime-hemp).
Yard - Photo © Pays de Fougères

6. www.libnam.eu 6
Performance
The building opened its doors
for the start of the school term in
April 2014. Therefore, there is no
feedback on the actual performance
of the building at this time.
The final blower door test indicated
a renewal rate of air of 7.67 vol/h.
(index n50) or 1.86 m3/h.m² (index
Q 4Pasurf).
The air tightness obtained did not
correspond to the objective of
1.7 m3/h.m² at 4Pa (obtained from
the thermal study) for this type of
building. During the intermediate
test the building was within this
threshold, but the need to respect
the law concerning access for
persons with reduced mobility
necessitated the installation of a lift:
this was placed in the heated area of
thebuilding(probablythroughalack
of familiarity associated with these
new constraints and / or difficulty
in meeting the architectural style
with the lift positioned outdoors).
Openings were made in the shell
of the building, the breathable
waterproof membrane was
therefore pierced to allow the lift to
go up and down without suffering
from a vacuum and suction effect.
This in turn allowed a significant
amount of air into the building.
The initial state of the building
showed a theoretical consumption
of 509 kWhEP/m² per year. The
thermal study gave 426 kWhEP/m²
(this drop is almost certainly due to
the higher than expected amount of
air entering the building).
As for CO2 emissions they dropped
from 140 kg eq.CO2/m².an with the
old method of heating to just 3 with
the use of the vertical geothermal
solution.
Entrance- Photo © Servane Guihaire - Constructys Bretagne

7. French-British collective Libnam7
Stakeholders
Project owner : Borough of Saint Marc le
Blanc
Project supervisor : Laurent et associés
(Fougères)
Thermal consulting firm : ECIE (Fougères)
Supervising office (Chartered building
surveyor) : Veritas (Rennes)
Structural work : CF Constructions (St Aubin
du Cormier)
Suspended ceilings : MORAND-BERREE (St
Jacques de la Lande)
Aluminium joinery : RETE Serge (Louvigné
du Désert)
Paint : FC Peinture (La Chapelle Janson)
Plumbing : GOUPIL Alain (Bazouges la
Pérouse)
Electricity : KALEO (St Germain en Coglès)
Wood joinery : HUMBERT Pascal (St Marc le
Blanc)
Tiling / screed : Sarl HUARD Jacky (Romagne)
Roofing : Sarl GOBE Didier (St Marc le Blanc)
Timber frame : ROBIDEL Sarl (Le Ferre)
Heating / ventilation : DELALONDE
Sébastien (Pontmain)
Dry walling / insulation : Sarl BARON-MILLE
(St Martin des Champs)
Hemp blocs / interior render / exterior
pointing (old building) : Etudes ET chantiers
(Rennes)
Lift : ABH
3D projection of the completed building - Photo © Pays de Fougères
Contact
Pays de Fougères
www.pays-fougeres.org

8. 8
Costs
Supervising office: £4,075
Project supervisor: £48,687
Structural work: £283,897
Suspended ceilings: £26,181
Aluminium joinery: £69,929
Paint: £28,450
Plumbing: £9,117
Electricity: £25,931
Wood joinery: £28,836
Lift: £14,827
Tiling / screed: £19,576
Dry walling / insulation: £29,790
Roofing: £40,503
Timber frame: £47,602
Heating: £52,354
Ventilation: £22,725
Hemp blocs / interior render: £35,145
Surface area Total: 776.45 sq m
Surface area Existing: 508.45 sq m
Surface area Extension: 268 sq m
Total (land excluded): £787,634 (£938,131
charges included)
Total existing: £490,197 (£583,667 charges
included)
Total extension: £297,436 (£354,464 charges
included)
Existing: £964 /sq m (£1,147 charges
included)
Extension: £1,110 /sq m (£1,322 charges
included)
Global: £971 /sq m (£1208 charges included)
The calculation of price per sq m was done
as a ratio proportional to the surface (65/35)
except for specific costs that were easily
identifiable by their function or directly
noted on the estimate.
The insertion workshop / integration project
is not subject to VAT.
Grants obtained : Eco-FAUR – £78,450 (case-
file developed with the help of Fréderic
MARCHAND of the Pays de Fougères).
Courtyard - Photo © Servane Guihaire - Constructys Bretagne