Whole life carbon assessment.
Operational energy is half the carbon. We measure the carbon locked into materials and construction next to the energy model, to EN 15978 and the RICS standard, so embodied and operational carbon are cut together. Mandatory under the EU framework from 2028.
What a whole life carbon assessment delivers.
What it isDrive operational energy down to Passive House levels and the carbon of running the building shrinks. What is left is the embodied carbon: the concrete, steel, insulation and finishes, and the construction itself. On a high-performance building that embodied carbon can equal or exceed everything the building will ever emit in use. Optimise the energy alone and you have measured half the problem.
We assess embodied carbon and whole life carbon next to the PHPP energy model, to EN 15978 and the RICS Whole Life Carbon Assessment standard, modules A to C. Structure, material and keep-versus-rebuild decisions are then made on the full carbon balance, not on operational energy. We tested Senan House this way and assessed it at 434 kg CO2e per square metre embodied. The same method underpins our portfolio decarbonisation work, where reusing existing fabric is usually the lowest-carbon answer, and it sits beside the Passivhaus design that holds the operational side down.
Modules A to C of EN 15978: A1 to A5 for product manufacture, transport and construction, B for use and replacement, C for end of life. Embodied plus operational, not operational energy alone, reported in kg CO2e per square metre so options compare on one number.
EN 15978 and the RICS Whole Life Carbon Assessment standard, built from Environmental Product Declarations (EPD) and recognised carbon datasets. Every figure traces to a declared source, so the assessment holds up to planning scrutiny and to the reporting mandate landing in 2028.
What an assessment covers.
DeliverablesEvery life cycle module in EN 15978, set against a benchmark, with a ranked list of the changes that bring the number down. The modules below are the structure of the report you receive.
The carbon of extracting and manufacturing every material: concrete, steel, insulation, glazing, finishes. Usually the largest single slice of embodied carbon, and the one most worth attacking early.
Transport to site and the construction process: site energy, formwork, waste and the carbon of installing the build. The end of upfront carbon, the part fixed the day the building completes.
Operational carbon from heating, cooling, ventilation and power, plus the embodied carbon of replacing components across the reference period. Run from the PHPP model so the operational figure is the real one.
Demolition, transport, waste processing and disposal at the close of the building life. Where reuse and recovery cut the figure, the assessment shows by how much.
The result in kg CO2e per square metre against RIBA and LETI targets, or the limit your reporting standard sets, split into upfront and whole life carbon so you can see which one is over.
A prioritised roadmap: the specific structural and material changes, ranked by carbon saved, that bring the building under target while the design can still move.
The numbers we work to.
We do not quote embodied carbon from a brochure. We model it. Senan House, the first certified Passivhaus office in Ireland and a building we designed, was assessed at 434 kg CO2e per square metre embodied carbon, comfortably under the 750 kg CO2e per square metre benchmark used for low-carbon offices. These figures are why the work moves up the priority list ahead of 2028.
Method: how we work.
MethodWe fix the assessment boundary, the RIBA or RIAI stage, and the standard the project answers to: EN 15978 and the RICS Whole Life Carbon Assessment standard, plus any local plan or ESG framework on top. This sets the modules, the reference period and the benchmark before any modelling starts, so the result is the one your planner, funder or auditor will accept rather than one they argue with.
The model is built from project quantities and the material specification, with EPD data and recognised datasets applied element by element. A product-specific EPD is used where one exists; where it does not, we apply a conservative generic figure and flag the spot where a better declaration sharpens the result. It runs alongside the PHPP energy model, and where the operational side needs more than steady-state, our dynamic simulation feeds the use-stage figure.
The structural system decides most of the upfront carbon, so we test it first: concrete against steel, timber, or a hybrid. Then the major material choices, then retrofit against new build. Each option is modelled on the same EN 15978 basis. The keep-versus-rebuild question and the structural question are answered with numbers, while the design team can still change course and the change is still cheap.
The result is reported in kg CO2e per square metre against RIBA and LETI targets, or the limit your standard sets, split into upfront and whole life carbon. The report closes with a ranked reduction roadmap: the changes, ordered by carbon saved, that bring the building under target. It is written to drop straight into a planning submission or an ESG report, ahead of the 2028 reporting mandate.
Common questions.
FAQWhat is a whole life carbon assessment?
A whole life carbon assessment, sometimes called a life cycle assessment or LCA, measures every kilogram of carbon a building is responsible for across its life, not its operational energy alone. It follows EN 15978 and the RICS Whole Life Carbon Assessment standard, covering modules A to C: A1 to A5 for product manufacture, transport and construction, B for the carbon of running the building and replacing components, and C for end of life. Embodied carbon is the carbon locked into the materials and the build. Operational carbon is the carbon of heating, cooling, ventilation and power. Whole life carbon is the sum, reported in kg CO2e per square metre so options can be compared on one number.
When does whole-life carbon reporting become mandatory?
Under the EU framework, whole-life carbon reporting becomes mandatory from 2028, and the Zero Emission Building (ZEB) standard follows for new buildings. This moves whole life carbon from voluntary best practice to a legal requirement, with the London Plan already requiring a whole life-cycle carbon assessment for referable development. The cheapest time to find that a project is over a limit is before the structure and the specification are fixed, which is years before 2028 for anything in design now. We unpack the regulation and what it means for design teams at the ZEB Summit.
Does building to Passivhaus increase embodied carbon?
Not by much, and the whole-life balance favours Passivhaus heavily. A Passive House carries more insulation, better glazing and an airtight, ventilated envelope, which adds some upfront carbon. The operational carbon saved across the life of the building outweighs that extra many times over, and a Passivhaus needs little or no heating plant, which removes carbon elsewhere. We designed Senan House, the first certified Passivhaus office in Ireland, and assessed it at 434 kg CO2e per square metre embodied carbon. Modelling embodied and operational carbon together lets us pick lower-carbon insulation, structure and finishes that hold the standard while cutting upfront carbon. The aim is to reach Passive House at the lowest whole life carbon, not to avoid it.
Is it lower carbon to retrofit or to demolish and rebuild?
Retrofit usually wins, because keeping the existing structure avoids the large upfront carbon of a new foundation, frame and envelope. A new build starts in embodied carbon debt that takes years of operational savings to repay, while a deep retrofit to EnerPHit standard reuses the carbon already in the building and cuts operational carbon sharply. The exceptions are real: a structure that is failing, unsafe or impossible to bring to standard. That keep-versus-rebuild call is exactly what the assessment answers. We model both routes on the same EN 15978 basis, modules A to C, so the decision rests on numbers rather than instinct.
Assess the full carbon balance.
Bring us in early, while the structure and the keep-versus-rebuild call can still change, and we model embodied and operational carbon to EN 15978 together. That is the cheapest point to land under target, and well ahead of the 2028 mandate. Talk to a consultant, or see how the same method shapes our portfolio decarbonisation work.