Earth Trust Visitor Centre
The Earth Trust is an environmental charity and this new building provides visitor and teaching facilities for their nature reserve at the Wittenham Clumps site in the Oxfordshire countryside.
The building makes extensive use of low impact sustainable materials with a glulam timber frame and Modcell straw bale walls. The straw bale panels are made on site using local straw from the farm operated by the Trust and provide excellent levels of insulation.
The straw bale panels are then rendered externally to make them weatherproof with a plasterboard internal finish. Internal walls are constructed from rammed earth taken from the site. The dramatically swooping intensive green roof includes native wildflower meadow plants to provide a truly diverse ecological environment for insects and birds.
The Trust has a particular interest in the water cycle and water conservation and seeks to include systems and technologies which clearly demonstrated how the water cycle works and how buildings can reduce water use. Rainwater is drained to a rill and then into a rainwater harvesting tank which is used to flush the toilets. The toilets use an innovative new technology, with a combined pneumatic and water flush using only 1.5 litres per flush. The building is naturally ventilated with opening windows and rooflights and heating uses an air-to-water heat pump with underfloor heating. All lights are highly efficient LED with automatic controls to reduce energy use.
Two small PV arrays on the building are supplemented by a larger array on the ground providing renewable electricity.