Montgomery School, Exeter
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Image courtesy of NPS Group.
Montgomery Primary School, Exeter, has been designed by Devon
County Council and NPS Exeter to be the UK’s first zero carbon
school built to the PassivHaus standard. The £9 million school will
cater for 420 pupils plus a nursery.
NPS Exeter started from the premise that the simplest way to
deliver a zerocarbon design would be to build a typical school,
replace the gas boiler with biomass and buy electricity via a green
tariff. However, they soon determined that such an approach is
unsustainable and without value. In addition, NPS Exeter wanted to
produce a scheme that had a modular design approach.
The school is designed to meet the stringent PassivHaus
standards which require buildings to have extremely low energy
usage whilst providing excellent comfort conditions in both winter
and summer. The PassivHaus design approach has a successful track
record in mainland Europe and has been used for the construction of
25 schools in Germany and Austria. The Flemish region of Belgium
has recently implemented a school building programme in which every
school is to be PassivHaus certified. Montgomery Primary School is
the first PassivHaus school in the UK.
Taking the requirements of zero carbon and PassivHaus on board
demanded that the following be met:
• Resource lean – adoption of the PassivHaus standard set a
limit of 15 kWh/m2/yr for heating, compared to the current demand
of between 113 – 164 kWh/m2/yr for a school built to current
• Super insulated – all components of the building envelope
insulated to a U-value below 0.15 W/m2/K • Air tight – minimal air
leakage, <0.6 air changes/hour which equals an air permeability
value of less than 1m3/hr/m2 @ 50 Pa
• Controlled ventilation – comfortable, healthy and sustainable
• Heat recovery – the major part of the warmth from exhaust air is
fed in again to the fresh air supply with a heat recovery rate
above 80 per cent with air being moved from high occupancy to low
• Zero carbon – all electricity provided on-site via
photovoltaics • Robust – the design is expected to not only pass
current requirements but to meet the demands of predicted future
climate to 2080.
These are tough demands that called for a construction approach
that offered future-proofed long-term performance. NPS determined
that the high thermal mass and airtightness of precast concrete
panels formed an important part of the solution. In order to
increase the cost-effectiveness and buildability of precast
prefabrication, a modular approach was developed where all the
classrooms were designed as identical units incorporating toilets,
cloakrooms and stores between. This also allowed the provision of a
draught lobby to maintain air temperature and control air leakage
whilst providing direct access to outside.
The high thermal mass and airtightness of the precast concrete
panels means that no traditional boiler is required. Rather, the
‘body’ of the ‘heat source’ are the pupils and teaching staff. The
variable air volume mechanical ventilation system will also be
provided with electric heater batteries to individual classrooms
for extreme weather circumstances.
The new Montgomery Primary School is currently being built
alongside the existing 1920s school which will then be demolished.
Montgomery Primary School is due for completion in August 2011 when
pupils and staff will find a building that combines 21st century
design and construction to provide an enhanced teaching and
Client: Devon County Council
Architect: NPS Group (Exeter)
Building services engineer: NPS Group (Exeter)
Quantity surveyor: NPS Group (Exeter)