Centre for Alternative Technology uses hemp walls

Walls built with hemp will be a major feature of a new building at the Centre for Alternative Technology (CAT) in Wales. Hemcrete is a mixture of hemp stalks, lime and a small quantity of cement. It produces less carbon emissions than conventional concrete, owing to the fact that cement is fired at high temperatures, using a lot of energy. The energy needed to make cement accounts for about 10% of carbon emissions globally. The walls are part of the new Wales Institute for Sustainable Education (WISE), a £6.2 million training and conference venue to extend its courses in sustainable technologies. The hemcrete material is sprayed onto heraklith (or woodwool) boards attached to the inside of the timber frame. The walls will be 500 mm thick, providing a high level of insulation and air tightness while remaining breathable. The walls will be finished inside and out with a lime render. Other carbon-saving features and technologies include 7.2 m-high rammed-earth walls for the 200-seat lecture theatre, making them the highest walls of this kind in Britain. Many of the foundations in the WISE building have been laid using limecrete instead of concrete. It also incorporates a large timber frame, sourced from sustainable forests, which use less energy to produce than a conventional steel structure. The heating and electrical demands of the WISE building will be met by a range of renewable resources. They include a CHP plant, burning woodchips, solar panels for electricity and hot water, hydroelectric turbines and several wind turbines.

Related links:

• www.cat.org.uk/