Low-carbon materials for walls

Does your home have eco-friendly walls? We look at two options with lower embodied carbon for more sustainable domestic builds.

In the UK, most one- to three-storey residential buildings have cavity walls. These are made of an inner wall and an outer one — which are usually block and brick respectively — with a small space (a cavity) between them.

The cavity exists to stop rainwater passing through the outer wall to the inside of the home. However, this empty space could be responsible for a third of all the heat lost from a property. Many homeowners have added insulation to combat this problem.

But it’s clear that cavity walls are not the most sustainable choice when building new structures, especially if you want to reduce your carbon footprint. Let’s look at two alternatives that we think have a lot of potential.

Kingsland Road renovation and extension project

Timber-frame wall with standard insulation

This option uses low-carbon materials to save about 30% of embodied carbon dioxide (CO2) compared to traditional cavity walls, even when the structure is clad with a brick slip.

We designed timber-frame walls with standard insulation and a brick slip on our Kingsland Road project in London. This is an energy-efficient home that also incorporates green technologies and features.

Hempcrete (or hemp-lime)

Hemp-lime can be used in different ways in wall construction, for example as an infill material or as blocks. A 2020 Institution of Structural Engineers (IStructE) report says that hempcrete blocks sequester carbon, which leads to negative embodied carbon values.

While hemp-lime is a traditional method developed in France for insulating timber-frame buildings, it is now being used for constructing new builds (both small and at scale) as well as restoring historic properties.

One example is The Triangle in Swindon, UK, by Glenn Howells Architects. The hemp-lime technique was used on this 42-unit development, which won several awards including the RIBA Regional Sustainability Award 2012.

Would you like a low-carbon home?

If you are thinking about embarking on building an eco-friendly home using sustainable materials, methods and technologies, please get in touch with us to find out how we can help you.

You can also read more about our alternative approach to sustainable structural engineering design that benefits people and planet, for stronger communities with a brighter future.