Key points
- Embodied carbon covers emissions associated with materials, construction and other stages of a building’s life; operational carbon covers emissions from energy and water use while it is occupied.
- UK built environment emissions fell by 14% between 2018 and 2024, against a required reduction of 24%. Embodied emissions rose by 5% over the same period (UKGBC, 2026).
- Embodied carbon accounts for approximately 50% of lifecycle emissions for new builds, according to UKGBC’s December 2024 research (UKGBC, 2024).
- Generally, 70–90% of embodied emissions occur before a building is occupied (IEA EBC, 2025).
- In CCBP’s early research, 59% of respondents described whole-life carbon assessment as selective, while 58% described policy as fragmented and inconsistent between authorities (CCBP, 2026).
Context
Operational carbon from buildings can fall as energy demand reduces and electricity generation decarbonises. However, UKGBC’s Whole Life Carbon Roadmap Progress Report 2025 reports that embodied emissions rose by 5% between 2018 and 2024, against a required reduction of 20%.
This briefing from the CCBP research team sets out how embodied and operational carbon differ, why their relative contributions are changing, and what this means for design and procurement decisions.
What is the difference between embodied and operational carbon?
Embodied carbon comprises greenhouse gas emissions associated with building materials and construction processes, including maintenance, replacement and end-of-life activities. Operational carbon covers emissions from energy and water used during a building’s operation, reported in modules B6 and B7 respectively under BS EN 15978 and the RICS standard.
Whole-life carbon brings these impacts together across a building’s life cycle. Consistent boundaries, assumptions and reporting periods are essential to make comparisons meaningful.
The table below shows how these emissions are grouped into stages of a building’s life, from manufacturing and construction through to maintenance and eventual demolition or reuse.
| Life-cycle stage | Modules | Type | Activities included |
| Product | A1–A3 | Embodied | Raw material supply, transport to manufacturing and manufacture |
| Construction | A4–A5 | Embodied | Transport to site and construction or installation |
| Use | B1–B5 | Embodied | Use-related material impacts, maintenance, repair, replacement and refurbishment |
| Use | B6–B7 | Operational | Operational energy use and operational water use |
| End of life | C1–C4 | Embodied | Deconstruction, transport, waste processing and disposal |
| Beyond system boundary | D | Reported separately | Potential benefits and loads beyond the assessed life cycle, such as reuse and recycling |
Source: BS EN 15978:2026 and the RICS Whole Life Carbon Assessment for the Built Environment, 2nd edition, Version 3 (August 2024).
Modules A1–A5 represent upfront embodied carbon. Operational carbon is reported separately in B6–B7, while module D is disclosed separately from the impacts in modules A–C.
Why the balance is shifting
As buildings become more energy efficient and the UK’s electricity supply becomes cleaner, the carbon emissions associated with operating them can fall. This means embodied carbon, which is associated with building materials, construction and other activities throughout a building’s life, can account for an increasing proportion of its total emissions.
UKGBC’s Whole Life Carbon Roadmap progress report, published in 2026, highlights this change across the UK built environment. Between 2018 and 2024, operational emissions fell by 21%, while embodied emissions increased by 5%. Overall emissions fell by 14%, well short of the 24% reduction required by the Roadmap (UKGBC, 2025 Progress Report, published 2026).
These figures show that progress in reducing operational emissions has not been matched by reductions in embodied emissions. They do not mean that improvements in operational efficiency have caused embodied emissions to rise. The amount and type of construction activity, together with material and construction choices, also influence embodied emissions.
Some measures designed to reduce operational emissions can nevertheless increase embodied carbon on an individual project. For example, installing additional insulation or more efficient building services may require extra materials and equipment, increasing upfront emissions while reducing energy consumption during the building’s use.
This is why both forms of carbon need to be assessed together. Embodied carbon can represent a larger proportion of whole-life emissions even when its actual emissions stay the same, if operational emissions are falling. At the same time, the reported rise in embodied emissions across the sector shows that these emissions need to be reduced in absolute terms too.
UKGBC estimates that embodied carbon accounts for approximately 50% of the life-cycle emissions of new buildings. The actual proportion varies depending on the building’s design, materials, energy performance and expected lifespan (UKGBC, 2024).
Where the trade-offs sit in design
The design challenge is to reduce whole-life carbon rather than optimise one category in isolation. A lower-carbon material choice may affect structural performance, building services, durability, maintenance or operational energy demand. Each option therefore needs to be assessed within a consistent whole-life carbon boundary.
Retention and refurbishment should be considered before assuming demolition and replacement will deliver the lowest-carbon outcome. Retaining an existing structure may avoid substantial new material production, although refurbishment requirements and future operational performance must also be assessed. The result depends on the building’s condition, intended use and assessment period.
Structural form and material specification can materially affect embodied emissions. Designers should compare feasible options using consistent quantities, functional requirements and data quality. Environmental Product Declarations (EPDs) can improve the specificity of product data, but comparisons must account for their declared units, scope and assumptions.
Building fabric and services require a whole-life comparison. Improving insulation, glazing or mechanical systems may increase upfront embodied emissions while reducing energy demand during use. The appropriate balance depends on anticipated operational savings, energy sources, replacement cycles and the assessment period.
Adaptability and replacement also matter. Design choices that extend service life, support future changes of use or reduce replacement requirements can affect modules B1–B5. End-of-life assumptions influence modules C1–C4, while potential reuse and recycling benefits belong in module D and should be reported separately.
These decisions are most useful when assessed early. By RIBA Stages 0–2, clients and design teams can still influence whether an existing asset is retained, the building’s form, the structural strategy and the specification. Later assessments remain valuable, but may have less influence over fundamental choices once the design and procurement route are established.
What CCBP’s research shows
CCBP’s ongoing research examines how whole-life carbon assessment is commissioned and used across public-sector construction. The study has included 35 interviews and five focus groups thus far with local authorities, contractors and consultants. Full findings are expected in 2027.
| Early research finding | Percentage |
| Respondents who said policy and regulation had no, limited or variable influence on whole-life carbon assessment implementation | 70% |
| Respondents who described the use of whole-life carbon assessment as selective | 59% |
| Respondents who described policy as fragmented, location-specific or inconsistent | 58% |
Source: CCBP, early research findings, 2026.
These early findings describe how whole-life carbon assessments are being used, rather than the emissions they measure. They suggest that having an assessment method available does not, by itself, mean carbon information will be used consistently when projects are being designed and procured.
The timing of assessment is particularly important. If whole-life carbon assessment takes place after the structural strategy, material specification or procurement approach has largely been fixed, it may identify impacts without allowing the team to change them. Introducing assessment early gives clients and designers more opportunity to compare options and consider embodied and operational carbon together.
Implications
Clients: Establish clear expectations for carbon performance at the outset of a project, including carbon reduction targets where appropriate and requirements for whole-life carbon assessment. Commission assessments early enough to inform important decisions, such as whether to retain an existing building, what form a new building should take and which materials should be used. Ensure assessments are updated as the project develops.
Consultants and designers: Consider both embodied and operational carbon when comparing design options. Be clear about where assessments rely on estimated quantities, generic carbon data or other assumptions, and update the calculations as more accurate information becomes available. During RIBA Stages 0–2, focus on decisions that can have the greatest influence on emissions, including building size and form, structural design, material use and energy efficiency.
Contractors and suppliers: Provide product-specific Environmental Product Declarations (EPDs) where available and identify opportunities to reduce emissions through material selection, construction methods and maintenance or replacement requirements. Early involvement can help project teams explore practical alternatives before designs and specifications are finalised.
Help shape the evidence
CCBP’s research continues to examine how whole-life carbon assessment can better inform construction decisions and where greater consistency is needed. Share your experience through the whole-life carbon assessment survey or explore CCBP’s whole-life carbon research.
FAQs
What is the difference between embodied and operational carbon?
Embodied carbon covers emissions associated with producing building materials, construction, maintenance, replacement and end-of-life activities. Operational carbon covers emissions associated with energy and water use while a building is in operation.
Why is embodied carbon becoming more important?
As buildings become more energy efficient and electricity generation becomes cleaner, operational emissions can fall. This makes embodied carbon an increasingly important part of a building’s overall impact. However, reducing embodied emissions also requires changes in how buildings are designed, constructed and maintained.
Does embodied carbon always account for half of a building’s emissions?
No. UKGBC estimates that embodied carbon accounts for approximately 50% of life-cycle emissions in new buildings, but this is not the case for every building. The proportion depends on factors including the materials used, energy performance, expected lifespan and how the building is maintained and operated.
Why is it important to assess embodied and operational carbon together?
Some decisions that reduce operational emissions can increase embodied carbon, and vice versa. Whole-life carbon assessment helps project teams understand these trade-offs and identify solutions that reduce emissions across the building’s entire life.