UK carbon measurement infrastructure is now mature. The RICS Whole Life Carbon Assessment standard, 2nd edition, mandatory for RICS members from July 2024, underpins most UK reporting requirements. The UK Net Zero Carbon Buildings Standard sets performance limits for buildings claiming net zero alignment. BREEAM Version 7 requires embodied carbon reporting at concept design, technical design, and post-construction stages. Alongside these, disclosure requirements and shared databases are making carbon performance visible and comparable across projects.
Alistair Thomas acknowledged the industry's progress in measuring whole life carbon but warned that reporting alone does not reduce emissions. While whole life carbon assessments can satisfy planning requirements, earn BREEAM credits, and support ESG reporting, they risk becoming compliance exercises if they fail to influence design decisions. His message was clear: the industry's focus must shift from measuring carbon to using that data to drive lower-carbon outcomes.
“A project that documents carbon perfectly and changed absolutely nothing in the design is, in the most precise sense of the word, a carbon accounting exercise. And it’s not what the industry needs.”
- Alistair Thomas, Associate Director and head of the UK LCA team at Buro Happold
Reviewing whole life carbon assessments across the industry, Alistair Thomas identified several recurring quality issues:
Missing building elements, resulting in incomplete assessments.
Incorrectly applied carbon factors, leading to inaccurate emissions calculations.
Incomplete transport emissions, often covering only the final leg of a product’s journey.
Partial MEP assessments, where only some building services are included.
Limited third-party verification, with no clear standard defining what an independent review should cover.
To improve confidence in assessments, Alistair Thomas called for defined evidence requirements for key materials, including concrete pour logs mapped to the relevant Environmental Product Declaration (EPD) and mill certificates verifying the source and specification of steel.
These shortcomings carry wider consequences than any individual report. Inconsistent results undermine trust in whole life carbon assessment, and without confidence in the numbers, organisations will not act on them.
Alistair Thomas’s first recommendation applies wherever you sit in the value chain:
“Our job is not to review or produce assessments only. Our job is to ask the difficult questions that change the design.”
- Alistair Thomas, Associate Director and Head of the UK LCA team at Buro Happold
Questions aligned with the PAS 2080 carbon reduction hierarchy, such as whether the project needs to be built at all, whether refurbishment can meet the brief, and whether materials are over-specified, require no detailed modelling. They require someone willing to ask them early enough for the answers to change something.
By technical design, the floor plate is largely fixed and most reduction opportunities are gone. Comparing massing, retention, and structural options at RIBA Stage 0 to 1, with carbon assessed alongside cost, energy, and daylight, keeps trade-offs visible before decisions harden. Early design tools such as Carbon Designer 3D support this kind of optioneering using only building type and size, so carbon enters the conversation before there is a detailed model to assess.
Flagship projects prove what is possible, but national performance is set by typical ones. Alistair Thomas offered a comparison worth remembering: a 5% embodied carbon reduction applied across the 300,000 homes the UK aims to build each year outweighs a 40% reduction on 50 flagship schemes. Making competent assessment and basic reduction measures standard practice on ordinary projects is the largest near-term opportunity the industry has.
Alistair Thomas closed the keynote with a test worth applying to every whole life carbon report that lands in your inbox: what question was asked that changed the design? Measurement and targets are necessary, but they are means, not ends.
“Be carbon movers, not just carbon measurers.”
- Alistair Thomas, Associate Director and Head of the UK LCA team at Buro Happold
A whole life carbon assessment quantifies a building’s greenhouse gas emissions across every life cycle stage, from product manufacture and construction through use to end of life, following BS EN 15978 and the RICS Whole Life Carbon Assessment standard. Software such as One Click LCA automates the calculation and produces reports compliant with UK frameworks.
There is no national mandate yet. The Greater London Authority requires assessments for referable schemes, a growing number of local planning authorities have similar policies, and the industry-proposed Part Z amendment would make assessment mandatory nationally. One Click LCA supports all major UK requirements, including the GLA methodology and RICS 2nd edition.
The RICS Whole Life Carbon Assessment standard, 2nd edition, is the UK reference methodology, cited by both BREEAM Version 7 and the UK Net Zero Carbon Buildings Standard. One Click LCA includes a pre-configured RICS 2nd edition tool aligned with the standard’s reporting structure.
As early as possible, ideally at RIBA Stage 0 to 1, while design options can still change. Early design tools such as One Click LCA’s Carbon Designer 3D estimate embodied carbon from building type and size alone, before a detailed model exists.