Acharacle Primary School: Sustainable school building study
Acharacle Primary School / Argyll, Scotland / Gaia Architects / Completion date May 2009 / Predicted annual CO2emissions 8.2kg/m²
This school for up to 80 students was almost entirely imported from Austria. A massive timber Brettstapel structure is fixed by glue-free, wooden dowels, insulated with woodfibre and clad in European larch. It has a U-value of 0.128W/m²K for walls and roof and 0.098W/m²K for floors. Triple-glazed windows are used throughout.
An impressive air permeability index of 0.27m³ per hour per square metre at a pressure of 50 pascals - perhaps the lowest to date in the UK - was achieved with the first test. With such airtight construction, specification of non-toxic materials was a high priority: clay plaster interior walls with natural paints, linoleum and solid Scottish oak floors. At Gaia’s insistence, furniture manufacturer Future Furniture redesigned its range to minimise off-gassing. Classrooms have individual monitors for CO2 levels. All rooms are naturally ventilated except the kitchen, WCs and the plant room.
External motorised blinds, located behind the cladding, are controlled by sun and wind sensors. They retract to prevent damage in high-speed winds.
A 6kW wind turbine sits on a 9m mast on a hill behind the school. Wind was selected over biomass because of its longterm sustainability.