UK-based architectural studio Cairn renovated and extended a Victorian house with reduced environmental impact, using amongst other materials hempcrete for the walls.

The aim of the project was to reduce the environmental impact of the renovation as much as possible. The architects minimised the use of steel, concrete and internal linings. This ensured a Lifetime Carbon figure of 40 per cent lower than if it had been built conventionally.

In the project, only essential new additions were made, while usable elements were retained or repurposed. Timber structures were used in place of conventional steelwork throughout, fully demountable at end-of-life. In cases that new materials were necessary, the architects opted for biobased, including cork, wood fibre, woodwool, lime plaster, and hempcrete. The exposed hemp walls are hand-cast.

The project is the UK’s first building structure to specify limestone calcined clay cement (LC3) concrete. If adopted universally, this material has the capacity to reduce global CO2 emissions by 1 tot 2 per cent.

Photos: James Retief / David Grandorge