CAT shows off WISE construction

The Centre for Alternative Technology has unveiled the innovative energy-saving technologies it is using in its new education building

The Powys-based Centre for Alternative Technology (CAT) is showing off the energy-saving technologies it is including in its new education building, the Wales Institute for Sustainable Education (WISE), as part of Energy Saving Week.

Energy Saving Week is a national initiative promoting energy efficiency running from 22nd to 28th October 2007.

The building design includes high levels of insulation, passive solar heating, natural daylighting, natural ventilation, energy monitoring systems and sophisticated control systems to regulate the temperature.

Instead of just looking at the energy used by the finished building, the ‘energy cost’ of the materials is being closely examined, and everything has been chosen for its low ‘embodied energy’ and reduced climate-changing emissions.

The most striking feature of WISE will be its 200-seat lecture theatre encased in circular rammed-earth walls. At 7.2m high they will be the highest load-bearing earth walls in the UK. Builders are currently ramming the first two of four sections.

These walls also reduce the energy required to heat and cool the building by absorbing heat from inside the building, reducing the need for mechanical air conditioning in the lecture theatre. On sunny days, the huge thermal mass of the structures will heat up, slowly releasing the heat throughout the day.

Large amounts of carbon dioxide are released when cement is manufactured, so concrete has been minimised in the design and architects have chosen alternative materials such as limecrete for the foundations, which actually absorbs CO2 as it sets.

Lime will also be used in the walls mixed with hemp, otherwise known as hempcrete. This will be sprayed onto the timber frame, making the walls airtight and reducing heat loss.

Even the bricks have been chosen for their low embodied energy levels. Instead of using energy-intense fired clay bricks, steamed sand and lime bricks have been selected. Using the bricks requires some careful design, but they work well with lime mortar.

Construction firm Frank Galliers Ltd have almost finished the timber building frame. The material’s Forestry Stewardship Council (FSC) certification guarantees it comes from sustainable sources, making it an environmentally-friendly alternative to steel.

CAT is monitoring every stage of the build, down to the energy inputs into each component of every brick. When complete, there will be large amounts of data on energy inputs in construction and use, making it a useful subject for students on CAT’s Architecture Masters degree.