Key points
- Embodied carbon accounts for roughly half of the life cycle emissions of a typical new building, and around one in every ten tonnes of UK greenhouse gas emissions (UKGBC, 2024).
- Typically, 70–90% of a building’s embodied carbon is emitted upfront, before occupation (IEA EBC, 2025). Most reductions are therefore fixed at design and procurement, not in use.
- UK embodied carbon emissions have risen since 2018, while built environment emissions overall have fallen by 14% since 2018, against the 24% reduction UKGBC’s net zero carbon roadmap required by 2024 (UKGBC, 2026).
- Around 46% of construction professionals are not measuring embodied carbon emissions across their projects (RICS, 2025). In CCBP’s research, 59% of respondents describe the use of whole life carbon assessment as selective.
Context
Operational emissions from UK buildings are falling as the electricity grid decarbonises. The government’s grid electricity conversion factor fell by around 26% in its 2026 update (Circular Ecology, 2026). Embodied emissions have not followed: UKGBC’s 2025 progress report found they have risen since 2018, offsetting gains elsewhere in the built environment.
Several European countries now set mandatory limits on the embodied impacts of new buildings. Denmark has applied limits to new buildings over 1,000 m² since 2023, France since 2022 under RE2020, and the Netherlands since 2018 using a monetised environmental performance metric (IEA EBC, 2025). In the UK, measurement remains voluntary outside a small number of planning authorities, including the Greater London Authority, Milton Keynes, Bath and North East Somerset, and Southampton (UKGBC, 2024).
This briefing from the Centre for Construction Best Practice (CCBP) research team sets out how embodied carbon is defined and calculated, and what early findings from its ongoing research into whole life carbon assessment (WLCA) show about why measurement practice still varies.
What is embodied carbon?
Embodied carbon refers to the greenhouse gas emissions, expressed in kilograms of carbon dioxide equivalent (kgCO₂e), attributed to a building’s materials and construction processes across its life cycle. Under BS EN 15978 and the RICS whole life carbon assessment standard, it is reported by module:
| Life cycle stage | Modules | Scope |
| Product | A1–A3 | Raw material supply, transport to factory, manufacture |
| Construction | A4–A5 | Transport to site, construction and installation |
| Use (embodied) | B1–B5 | Use, maintenance, repair, replacement, refurbishment |
| End of life | C1–C4 | Deconstruction, transport, waste processing, disposal |
| Beyond the system boundary | D | Reuse, recovery and recycling potential, reported separately |
Modules A1–A5 together form upfront carbon. For embodied carbon in buildings, this distinction matters. As 70–90% of embodied emissions occur before occupation, the scope to reduce them narrows quickly once the design is fixed. Operational energy and water (B6–B7) sit outside embodied carbon; together, the two make up whole life carbon.
How to calculate embodied carbon
At its core, an embodied carbon assessment multiplies the quantity of each material by an emission factor and sums the results across the modules in scope. Transport, site activity, replacement and end-of-life scenarios are modelled alongside.
In the UK, the RICS whole life carbon assessment standard (2nd edition) sets the method. The IStructE guide, How to calculate embodied carbon (January 2025) applies it to structures.
- Define the system boundary. Set the building elements, modules and reference study period in scope (60 years for buildings under the RICS standard)
- Quantify materials. Take quantities from the cost plan or BIM model, structured by building element so results can be compared across projects.
- Select emission factors. Prioritise product-specific Environmental Product Declarations (EPDs) over sector-average and generic data. The choice is material: a 2025 statistical analysis of several hundred EPDs found the global warming potential of ready-mixed concrete varies significantly by strength class, driven by cement content (Asdrubali et al., 2025).
- Apply a contingency. The RICS standard requires an allowance that reflects design stage and data quality, so early-stage results are not under-reported.
- Report and benchmark. Report results by life cycle module, using the categories above, and express building-level results in kgCO₂e per square metre of gross internal area. Compare results with benchmarks or limits covering the same building elements and life cycle modules.
An embodied carbon calculator can support early optioneering. The free Structural Carbon Tool (version 3, January 2025) is aligned with the IStructE guide and the tool also uses the Structural Carbon Rating Scheme (SCORS), which benchmarks the upfront embodied carbon of a building’s structure. Whole-building assessments generally use life cycle assessment software.
Why measurement and assessment still vary
Measurement and assessment of embodied carbon and whole life carbon varies significantly across the UK as it often depends on client policy as opposed to regulation. Even in London, where the London Plan requires assessments for referable schemes, 72 of the 93 applications approved in 2023 carried one out (IEA EBC, 2025).
CCBP is examining whether greater consistency in policy and practice would lead to more consistent use of whole life carbon assessment, of which embodied carbon assessment is a core component. The study so far comprises 35 interviews and five focus groups with local authorities, contractors and consultants.
| Early finding on whole life carbon assessment | Respondents |
| Policy and regulation have had no, limited or variable influence on implementation | 70% |
| Use is selective | 59% |
| Policy is fragmented, location-specific and inconsistent between authorities | 58% |
Early findings from CCBP’s whole life carbon assessment research. Full findings will be published in 2027.
Four themes are emerging:
- Timing. Assessments are frequently commissioned after the design is substantially fixed, when they record outcomes rather than inform them. Given that for many new buildings, a substantial share of embodied carbon arises before occupation, through material production and construction, this can limit their value.
- Data quality. Results depend on whether product-specific or generic emission factors are used. UKGBC’s roadmap set a target for 40% of construction products to have EPDs by 2025, and 100% by 2030 (UKGBC, 2024).
- Readiness. Capability to commission, deliver and act on assessments differs across clients, consultants and the supply chain.
- Practicality. There is no consensus yet on what a nationally consistent approach would require.
The research is timely given the policy landscape is shifting rapidly. In March 2026, the National Infrastructure and Service Transformation Authority (NISTA) published new Whole Life Carbon Management guidance for infrastructure and the built environment. UKGBC has also called for clear government direction, and its Embodied Carbon Summit evidence report (February 2026) records industry calls for national consistency in whole life carbon methodologies.
“The way whole-life carbon assessment is being approached varies significantly, and those inconsistencies have knock-on effects for the supply chain, capital and operational expenditure, and ultimately the environment we live and work in.” Conor Neild-Crabb, Head of Centre, CCBP
Implications for each construction project
Carbon considerations should inform the project from RIBA Stage 0, including whether existing assets can be retained or adapted. Early assessments at Stages 1–2 can then inform the brief, structural form and material strategy while these decisions remain open. Assessments should be updated through design, procurement and construction to identify further reductions and check delivery against targets.
- Clients can specify embodied carbon targets, the assessment standard and the stage of first assessment in the brief and procurement documents.
- Consultants and designers can assess structural and façade options comparatively, and report the data type behind each result so that figures are comparable.
- Contractors and suppliers can provide product-specific EPDs and propose lower-carbon alternatives while the specification is still open.
The last point depends on the RIBA stage at which the supply chain is appointed. CCBP’s study of 412 public sector projects found that, on average, costs held to budget when contractors were appointed by RIBA Stage 2. Early appointment also gives the supply chain the opportunity to reduce embodied carbon before the design is fixed. Survey respondents appointed at RIBA Stages 1–2 reported:
| Outcome | Respondents appointed at RIBA Stages 1–2 |
| Influenced sustainable design initiatives across their project | 97% |
| Contributed to value engineering that reduced overall project costs | 96% |
| Directly employed apprentices (86% when appointed at RIBA Stage 4) | 94% |
Source: CCBP, Constructing Certainty.
Help shape the evidence
CCBP’s whole life carbon research continues into 2027. We want to hear from clients, contractors, consultants and the wider supply chain, whether you assess embodied carbon on every project, some projects or none.
Take the whole life carbon assessment survey
Read more on our whole life carbon research.
FAQs
What is an embodied carbon assessment?
A quantification of the embodied carbon of a building or design option, reported by life cycle module. It often forms part of a whole life carbon assessment, which adds operational energy and water (B6–B7).
Is there a free embodied carbon calculator?
The IStructE Structural Carbon Tool is free and covers structural elements. Whole-building assessments generally require life cycle assessment software and EPD data.
What is the difference between embodied carbon and embodied energy?
Embodied energy measures the energy used in the material and construction activities included in an assessment, usually expressed in megajoules (MJ). Embodied carbon measures the associated greenhouse gas emissions, expressed in kgCO₂e. These include emissions from energy use and from processes such as cement manufacture. The two measures are related but are not interchangeable.
Is embodied carbon regulated in the UK?
Not nationally, though some planning authorities require whole life carbon assessments. Countries like Denmark, France and the Netherlands already set mandatory limits on the embodied impacts of new buildings.