Colour Casing

by Anna Beckett

15th January 2024

Last year's juror Anna Beckett, Associate Director at Buro Happold, discusses how Colour Casting successfully exemplifies an achievable low-carbon and structural solution to a standard extension.

Among the shortlist for the Don’t Move Improve awards last year, I was pleased to see a number of projects that had taken a low-carbon approach to the structural design but in particular Colour Casing stood out as a project that demonstrates how this can be done for even a standard extension. For most small family homes, especially terraces, the usual approach is to remove the rear wall across the full width at the ground floor and extend into the garden. In order to achieve this a significant steel frame is required to support the wall above and re-instate the stability that the masonry would have provided. But at Colour Casing (and similarly at Low Energy House) they had cleverly retained a limited part of the rear wall so that framing wasn’t required for stability and the wall above was supported by a relatively modest lintel.

The retained masonry was incorporated into the kitchen design so that the space still had that open plan feel, but the structure, and resulting embodied carbon, was significantly reduced. The extension itself, described by District Architects as “a loft extension on the ground”, was constructed in timber making it both lightweight and low carbon. As a result, the foundations were also reduced, with the extension supported on a series of small concrete pads, rather than the strip footings you’d need for a masonry wall. 

Whilst it’s easy to overlook embodied carbon in home extensions there are lots of opportunities to make savings, and with 1 in 20 homes in London submitting a planning application for an extension in 2021, it’s clear that the collective embodied carbon is significant. Colour Casing is a great example of the carbon reductions that can be achieved with relatively minor compromises, and with a clever approach to the architecture, this can be done without impacting the budget or the space provided.