WWT London Wetland Centre | Barnes, London 2008

Through the use of Cement Stabilised Rammed Earth this bat roost design for the London Wetlands Centre incorporates a range of environmental conditions within an externally unified form. The construction method is similar in principle to that of in situ steel reinforced concrete: formwork is erected into which a damp mixture of earth, clay and cement is compressed over a number of layers. Rammed Earth construction is an inherently sustainable building method – the raw material is almost universally available. Critically with regard to this design it has an extraordinarily high thermal mass, keeping temperature fluctuations to a minimum. It also forms a natural barrier to cold wind, insects and rodents and is fireproof and sound proof.

Clay and mud would be sourced directly from the London Wetland Centre – in this way the colouration and texture of the site is manifest in the material of the roost. Lichens, mosses and other clinging plants would be encouraged to colonise the outside of the rammed earth.

The concrete of the foundation, combined with the earth under which it is buried, will provide the most climactically stable environment in the whole structure – where the rammed earth ensures stability over the daily cycle, the foundations will provide seasonal stability.