Work is about to begin on The Wales Institute for Sustainable Education (WISE), a new complex intended to showcase the very latest thinking in environmentally-conscious building design at the Centre for Alternative Technology (CAT), near Machynlleth in Wales. Among the innovative features of the building will be construction of rammed earth walls in the Institute’s lecture theatre. The 7.2m high rammed earth walls, which are load-bearing and made of excavated subsoil, exemplify this approach. The clay content of the soil means no additional binding material will have to be added. The walls are packed down in layers, using hand-held pneumatic compactors, between temporary formwork.