1. 52
This timber framed building took
an innovative approach to straw
bale insulation.
The Governors of the Bishop Cornish School had a vision of the inspiring
space they wanted for their children. Completely undeterred by a lack of
funding, they pursued their vision for six years to make the building a
reality. The Education Centre has transformed the services they are able
to offer – and was built with a huge amount of support and goodwill from
the community. The building itself is a highly insulated timber-framed
structure featuring straw bales, solar panels and a green roof. An important
innovation is that the bales are stacked vertically inside the timber frames.
Introduction
Truro
Exeter
Saltash
Bishop Cornish School
Key dates
2004 : the Governors of Bishop
Cornish Church of England
Primary School set up and
incorporated a Charity -
the Bishop Cornish Education
Centre
2004-09 : fundraising by the
school and community
2009 : construction
March 2010 : official opening
by the Countess of Wessex
Outside - Photo © Bishop Cornish School

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Context
In 2004, the Governors of the Bishop
Cornish School set up a charity with
the aim of building an Education
Centre to extend the range of
services they could offer to the
community. The charity’s trustees
wanted a building to accommodate
before and after-school care, pre-
school, music and environmental
education. They were due to start
looking at estimates for a standard
prefabricated building, when they
heard about a pre-school building
at Lanlivery in mid-Cornwall,
which had won a prestigious RICS
International Sustainability Award.
After talking to the architect, Martin
Penk from Arco2 Ltd, they visited
Lanlivery and realised this was
exactly the type of building they
really wanted.
The decision to commission a fully
bespoke sustainable building set the
trustees on a path that would take
years of planning and fundraising,
but which led to an inspiring story
of community support and resulted
in a unique building.
The building ethos as defined by
the trustees was:
“To design, construct and use an
Education Centre that will serve
as an educational tool through
being an exemplar of innovative
and sustainable development.
In particular : maximise the use
of natural sunlight, apply the
principles of passive solar design
Plan © Arco2 Architecture
N

3. French-British collective Libnam3
and effortlessly accommodate the
sloping site.
All materials assessed to ensure that
only those with a low embodied
CO2 content (through sourcing,
processing and transportation) are
used.
The life cycle of materials considered
to minimise wastes arising at all
stages. Recycled materials used
where available.”
The architect worked closely with
the school to achieve these aims
and the resulting building comprises
280 m² of interior space including; a
main carpeted play area, spaces for
soft and for messy play, a quiet area
and semi-circular music room.
Building overview
The focus for material selection
was to use natural materials with
low embodied CO2, sourced from
Cornwall where possible. Where
high embodied energy materials
were required, the design ensured
they were kept to a minimum. With
this in mind, the foundations are
restricted to cement concrete pads
each measuring 750 mm x 750 mm.
This method enabled the architect
to easily accommodate the sloping
site.
The pad foundations support posts
holding a frame of natural timber
and glulam beams (engineered
timber made from low grade
wood laminated together to
form extremely strong structural
elements). The external walls are
formed from untreated Douglas fir
cladding, bitumen board panels and
straw bale insulation. Bargeboards,
fascias and soffits are all in
untreated Douglas fir and cedar. The
timber window and door frames
are pre-treated with water-based
preservative coatings. The floors are
insulated with natural sheep’s wool
beneath 18 mm chipboard and are
finished in a variety of materials
including engineered oak and
natural linoleum.
Part of the building is roofed in
Elevation © Arco2 Architecture
Elevation plane © Arco2 Architecture

4. 55www.libnam.eu 4
Technical focus :
Straw bales
Straw bales insulate all the external
walls and are sandwiched between
two timber frames.
The key design innovation in the
Bishop Cornish building is that the
bales are stacked vertically inside
the timber frames. Most straw bale
buildings use the bales horizontally
recycled rubber tiles and part has
a green roof composed of sedum
planted in 50 mm substrate over
a waterproof membrane, marine
grade ply wood and sheep’s
wool insulation. The building has
underfloor heating which was
originally served by a high efficiency
condensing gas boiler, and has
since been replaced by a biomass
boiler. The school has also installed
a 9.6 kW solar photovoltaic array.
– stacking them in a pattern similar
to brickwork. Vertical stacking
means that the 380 mm-390 mm
wide bales can be fitted in between
vertical studs spaced at 400 mm
along the length of the walls. This
in turn means that standard width
(e.g.1200 or 2400 mm) sheet
materials can be used throughout
– making the build faster, more
efficient and less wasteful. This
method has proved very effective
and has since been adopted in a
pre-fabricated straw bale system,
«Ecofab», developed by Arco2
Architects – Bishop Cornish has thus
been an important innovator for
straw bale construction in Cornwall.
The exterior timber frame is
sheathed in 22 m Steico sarking
board and the interior frame with
two layers of plasterboard. A
Timber frame - Photo © Bishop Cornish School

5. French-British collective Libnam5
25 mm service void sits between
the two layers of plasterboard; the
double layering also acting as a fire
retardant feature. The depth of the
bales gives 500 mm of insulation
between the two timber frames.
The internal and external frames
are tied together by 200x500 mm
plates of OSB board fixed between
the corresponding studs on each
frame at a height of 800 mm and
1600 mm.
During construction, the outer
skin of sarking board and the OSB
plates were installed first, and the
straw bales packed against these.
The 400mm spacing between the
studs meant that the bales had to
be squeezed in tightly and it was
sometimes difficult to make them
fit. Around windows and in other
irregular spaces, sheep’s wool was
packed in as an alternative to the
straw.
The bales are placed so that the
string which binds them is protected
between the bales and the cut ends
of the straw are pressed against
the interior and exterior sheet
materials. This means that the grain
of the straw runs across, rather than
with the direction of, the wall and
contributes to its rigidity.
An advantage of this construction
method is that it uses standard
timber frames which do not demand
specialist skills. The contractor for
Bishop Cornish had not used straw
before, but he and the architect had
worked together and through good
on-site communication the build
did not present too many technical
challenges.
The size and dramatic form of the
building, with its curved music
room, pushed the limits of this type
Entrance - Photo © Bishop Cornish School

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Barriers and solutions
The principle obstacle faced by the
project was one of funding, and the
school turned this into a virtue by
making it the focus of a campaign
to bring the community together
and created a real sense of local
investment in the project.
Working tirelessly, the charity and
community raised over £350,000.
Parents and friends of the school
supported the project through a
plethora of fundraising activities
including repairing bicycles,
valeting cars and by donating
materials, labour and skills to the
construction. Generosity from local
companies included the donation of
water pipes and roofing tiles. HMS
Raleigh provided manpower to help
of construction in Cornwall. It has
thus served as an exemplar of the
scale, form and function that can
be realised using timber and straw,
a fact which was recognised by its
inclusion in the 2014 edition of the
Pevsner Guide to Cornwall.
The straw bales used in the building
were locally sourced from ex-parents
of the school who are farmers.
The school always recognised the
importance of the building as a
learning tool and the children learnt
about sustainable construction by
helping to install the straw bales.
Green roof - Photo © Bishop Cornish School

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Awards
2010 • RICS South West
Community Benefit Award
• National Green Apple
Award for Best Educational
Establishment
• Finalist, RICS International
Sustainability Award
2011 • National Winners
• Outstanding School
Governing Body of the Year 2011
(National Governors Association)
for the vision, leadership and
Stakeholders
Client : Bishop Cornish Church of England
Voluntary Aided Primary School
Architect : Martin Penk, Arco2 Architects,
Bodmin
Prime contractor : Shaun Bunney, Bodmin
Glazing : Stonehouse Glass, Plymouth
Windows : Nordan
Marmoleum flooring : Forbo Nairn
Kitchen : Howdens, Saltash
commitment that resulted in the
provision of the Bishop Cornish
Education Centre
2014 • Inclusion in the new 2014
edition of the Pevsner Architectural
Guide : The Buildings of England -
Cornwall
in the installation of the sedum roof.
The project brought together the
entire School and wider community.
Music class - Photo © Bishop Cornish School
Contact
Cornwall Sustainable Building Trust
http://csbt.org.uk/