As the UK Construction industry is working to reduce its carbon emissions, our technical director, John Smith, gives an insight into why embodied carbon is critical in ensuring this succeeds.

The journey to Net Zero Carbon homes is well underway, with the first Building Regulations changes already in effect as we work towards the Future Homes Standard. From 2025, newly built homes will need to be ‘zero carbon ready’, with a 75% reduction in carbon emissions to 2021 levels in England and Wales, and a 57% reduction in Scotland.

At Donaldson Timber Systems, we’ve been advocating for this build method for over 15 years. Our BOPAS Plus accredited and BBA certified Sigma® II Build System is designed to achieve superior levels of fabric performance, suitable for projects which are seeking to achieve the very highest fabric efficiency and airtightness standards.

For us, the most crucial factor when it comes to reaching true zero carbon, is embodied carbon. Embodied carbon is the total greenhouse gas emissions generated in production and manufacturing of an asset. It can be calculated in two separate elements: from raw material extraction through to construction of the building on site, including fuel and power for transport, factories and plant; and end-of-life emissions from demolition, transport from site and recycling / landfill.

In a new home completed to 2021 standards, embodied carbon from the construction and end of life demolition and disposal is around 15% of the whole life carbon emissions, with the rest from the operational heating and power. With a target to reduce emissions by 75% through operational carbon reductions, the embodied carbon becomes much more significant at up to 60% of the whole life emissions.

It is therefore crucial that the embodied carbon of new building fabrics designed for 2025 standards are understood, to ensure that any savings in operational carbon are not offset by the introduction of a building fabric with high embodied carbon.

When we factor embodied carbon into the zero-carbon journey, timber really comes into its own. As the only naturally renewable building material, timber build solutions are undeniably the most sustainable form of construction. Using a timber frame build system for a 2021 new-build home reduces the embodied carbon by around five tonnes, compared to a masonry construction home of the same fabric performance. This carbon saving will undoubtedly increase as the building fabric performance is increased to achieve 2025 levels.

Timber frame homes are more environmentally friendly during the build, when the building is in use and throughout its lifetime. Timber can also lower or offset its embodied carbon thanks to sequestration – absorbing atmospheric CO2 while the tree is growing and storing it until the timber is incinerated or goes to landfill at the end of its use. Around one tonne of CO2 is stored in every m³ of timber.

While we’ll continue to campaign for the legislation of embodied carbon, many organisations will reach the conclusion that they need to consider the full process to meet their corporate sustainability goals. In recognition of this, we’re working with our customers to help measure the sequestered and embodied carbon for all our build systems.

Through experience, measurement, and science, we can demonstrate that timber offers an ideal solution to achieve true net zero carbon targets. One day, every home will be built this way.