Charlie Law, Sustainability Director at Timber Development UK (TDUK) believes the case for setting and understanding embodied carbon measurement has never been more important.
We have probably all read the statistic that the built environment is responsible for around 40% of global greenhouse gas emissions, and over many years there has been much attention, rightly so, on the operational emissions from lighting, heating and cooling our buildings, with subsequent upgrades to efficiency and thermal performance. However, we have only recently started to tackle embodied carbon, which according to the UK Green Building Council, currently makes up 20% of all built environment emissions.
To understand how much embodied carbon is tied up in your building (i.e. how much carbon is emitted to produce and maintain the building) we do need to measure it. The RICS Professional Standard for Whole Life Carbon Assessment for the Built Environment sets out how this should be done. Ideally you should be aiming for a whole life carbon assessment which includes the upfront carbon emitted up to handover (A1-A5), and emissions from use, maintenance, repair, replacement and refurbishment (B1-B5), operational energy and water (B6-B7), and end of life demolition and processing (C1-C4). However, as a minimum you should aim to measure at least the upfront carbon (A1-A5).
So how can timber help reduce the embodied carbon of your building? The use of timber can really help reduce the embodied carbon as the processing of timber is a low carbon activity. Even though much of the timber we use in the UK is imported from other countries, the total emissions including transport are still very low. For example, the latest TDUK Embodied Carbon Data for Timber Products knowledge sheet shows that the weighted average A1-A4 emissions (i.e. from felling to delivery to a UK construction site) for a piece of softwood are 87kgCO₂e/m3 (excluding the biogenic carbon sequestered by the tree during growth and stored in the timber). If UK grown softwood was specified, this figure is reduced to 71kgCO₂e/m3. This is compared to the average A1-A3 emissions (cradle to factory gate) for UK concrete mixes, from the Concrete Centre, which are around three times higher at 242kgCO₂e/m3.
Based on a study by Arup for Defra in 2025, using timber in the superstructure achieves whole life embodied carbon reductions for all building archetypes. Whole life embodied carbon reductions for the structure alone are up to 35%, whereas for the whole building, embodied carbon reductions are up to 9% (though these will vary by archetype). Considering that the Arup report used an older, higher average, embodied carbon figure for timber, these are impressive results. So how do we get more low carbon housing built?
First, we need to ensure embodied carbon is taken seriously and measured. Many larger developers are already insisting on embodied carbon measurement, either upfront or whole life data. There are also tools that allow the embodied carbon to be quantified, e.g. One Click LCA Building whole life carbon tool, or the Future Homes Hub Carbon Assessment Tool specifically for housebuilders.
Secondly, once we have enough measurement data, we need to set carbon limits for different types of buildings. For example, the UK Net Zero Carbon Building Standard (UK NZCBS) suggests an upfront limit of 400kgCO₂e/m2 for single family homes for 2026, reducing to 190kgCO₂e/m2 by 2035.
Currently there is no legal requirement for embodied carbon measurement, where there is for operational energy. This is where the Part Z campaign could help. This industry led campaign is urging Government to introduce a requirement in Building Regulations to measure embodied carbon, and in the future, set carbon limits. We would encourage readers to join TDUK and many other organisations from across the supply chain to sign up and support this campaign.
Only by measuring, and setting carbon limits, will we be able to reduce the embodied carbon impact of the built environment.
Read the full article here
