Ireland's updated national methodology for calculating life cycle GWP in new buildings

Ireland now has an approved national methodology for calculating the life cycle global warming potential (GWP) of new buildings. The Sustainable Energy Authority of Ireland (SEAI) published Version 2.0.0 of the methodology following a 2025 public consultation, alongside an updated national database of generic building material carbon factors and a revised calculation workbook. Together, these set out how Ireland will meet its obligation under the recast Energy Performance of Buildings Directive (EPBD) to calculate and disclose life cycle GWP on new buildings, starting with large buildings in 2028.

What the updated methodology delivers

Ireland's methodology sets out a step-by-step process for calculating a building's life cycle GWP across every stage: production and transport of construction materials, on-site construction, everyday use, maintenance and replacement, operational energy, and end of life, including any benefit from reuse, recycling, or exported energy. Results are calculated over a 50-year reference study period and reported in kilograms of CO2 equivalent per square meter of useful floor area, in line with Annex III to the recast EPBD as amended by Delegated Regulation (EU) 2026/52.

"The transition from voluntary benchmarking (the earlier INDICATE project) to the national standard that becomes mandatory for every new building by 2030."

- Steven Zijlstra, Product Marketing Manager, One Click LCA

A central feature of the methodology is its data hierarchy. Assessors must use verified product-specific data, drawn from Declarations of Performance and Conformity or Environmental Product Declarations (EPDs), wherever it is available. Where it is not, generic data from Ireland's own national database applies instead, followed by SEAI's default values as a last resort. The methodology also sets mandatory contingency margins by project stage: 15% at early design, tapering to 6% by technical design and construction, to account for the uncertainty inherent in earlier-stage estimates.

Understanding the phased timeline

Ireland is not introducing this requirement all at once. The key dates are:

• September 1, 2025: Public bodies commissioning new buildings with exchequer funding above €10 million (non-residential) or €60 million (residential) must produce or procure a whole life carbon assessment. This is already in effect.
• June 1, 2026: That funding threshold drops to €5 million (non-residential) or €30 million (residential), bringing more public projects into scope.
• September 1, 2026: SEAI's Version 2.0.0 methodology becomes the approved national reference for these assessments.
• January 1, 2028: Life cycle GWP disclosure on the Building Energy Rating (BER) certificate becomes mandatory for all new buildings with a useful floor area over 1,000 square meters.
• January 1, 2030: The disclosure requirement extends to all new buildings, and EU Member States must begin setting whole life carbon limit values under Article 7(5) of the recast EPBD.

For public sector projects, this is already a live requirement, not a future one.

What changed since the draft version

SEAI issued Version 1.0.0 of the methodology as a draft in April 2025 for public consultation. Version 2.0.0, published in 2026, is the approved version following that consultation. Alongside it, SEAI's National Embodied Carbon Database of Generic Building Materials now includes 214 generic material emission factors covering the product stage (A1 to A3), and the accompanying Calculation Workbook has been updated to reflect this. Both the database and the methodology are expected to be revised again as more data becomes available and as EU guidance develops further.

Implications for architecture, engineering, and construction teams

Project teams working on new buildings in Ireland need to plan for life cycle GWP reporting earlier than the 2028 disclosure deadline suggests. If your projects rely on public funding above the current thresholds, a whole life carbon assessment is already a live procurement requirement. If they do not, the calculation habits, data sources, and reporting formats built now are the same ones that will be mandatory in a few years' time.

This also changes how early design decisions get made. Because the methodology allows generic, database-driven figures at early design and expects those to be replaced with verified product data as a project matures, material and structural choices made at concept stage can be revisited with real numbers later, rather than guessed at once and left unchecked.

4 steps for compliance

A few practical steps stand out for Irish AEC teams getting ready for this requirement:

1. Understand the data hierarchy. Know which data source your project should be using at each stage, and do not default to generic figures once product-specific EPDs are available.
2. Bring life cycle assessment into early design. The methodology is built around a progression from generic to specific data, so early involvement of a life cycle GWP assessor pays off later.
3. Track the Green Public Procurement thresholds. If a project has exchequer funding, confirm whether it already meets the criteria requiring an assessment today.
4. Use software built for the methodology. Manually replicating SEAI's data hierarchy, contingency factors, and reporting format in a spreadsheet is possible, but time-consuming to keep current as the methodology and database are revised.

Challenges practitioners are already facing

Two misconceptions come up often. The first is that this requirement only applies to large buildings. It does not: the 1,000 square meter threshold in 2028 is a phase-in step, and the requirement extends to all new buildings from 2030. The second is that this is a 2028 problem. For public bodies on qualifying projects, the requirement to produce a whole life carbon assessment has applied since September 2025.

Beyond that, data availability remains a real constraint. Ireland's national database currently covers 214 generic material factors for the product stage alone, so early-stage assessments still rely heavily on generic data and default values rather than verified, product-specific figures. Applying the mandatory contingency and cost adjustment factors correctly, particularly for bill of quantities items without a matching carbon factor, also adds a layer of complexity that teams accustomed to simpler carbon calculators will need to learn.

How this connects to other whole life carbon standards

Ireland's methodology was not built from a blank page. SEAI's development process drew on several existing frameworks, including the RICS Whole Life Carbon Assessment standard, 2nd edition, the IStructE's guidance on calculating embodied carbon, and the IGBC's INDICATE methodology. Practitioners already familiar with RICS V2 reporting will recognize the same underlying logic in Ireland's approach: a life cycle scope covering embodied, operational, biogenic, and end-of-life carbon, calculated with cost data in mind.

How One Click LCA supports compliance in Ireland

One Click LCA is aligning its calculation tools to Ireland's approved national methodology, following the same approach taken with other national systems, including Iceland's mandatory life cycle assessment requirement introduced in 2025 in partnership with Iceland's Housing and Construction Authority (HMS).

"One Click LCA's product team is already working to update and support the version 2 of the Irish national methodology in the platform as soon as possible," says Steven Zijlstra, Product Marketing Manager at One Click LCA.

Key takeaways for architecture, engineering, and construction (AEC) teams in Ireland

• This is live for public projects today, not a 2028 problem. Check whether your project already meets the Green Public Procurement funding thresholds.
• Learn the data hierarchy now. Knowing when to use product-specific data versus generic or default data is central to a compliant assessment.
• Plan for revisions. SEAI has already signaled that both the methodology and the national database will be updated as more data becomes available.

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Frequently asked questions

1. What is Ireland's life cycle GWP methodology?

It is SEAI's national technical methodology for calculating and reporting the life cycle global warming potential of new buildings, developed to meet Ireland's obligations under Article 7(2) of the recast EPBD.

2. When does it become mandatory?

Disclosure on the BER certificate becomes mandatory for new buildings over 1,000 square meters from January 1, 2028, extending to all new buildings from January 1, 2030. Public bodies on qualifying government-funded projects have needed a whole life carbon assessment since September 1, 2025.

3. Does this only apply to large buildings?

No. The 1,000 square meter threshold in 2028 is a phased first step. The requirement applies to all new buildings from 2030.

4. Is this only relevant to the public sector?

No. While public bodies are the first group required to act, under the current Green Public Procurement thresholds, every new building in Ireland will eventually need to disclose life cycle GWP, regardless of ownership.

5. What data should be used, and when?

The methodology sets a strict hierarchy: verified product-specific data first (from Declarations of Performance and Conformity or EPDs), then generic data from Ireland's National Database of Generic Building Materials, then SEAI's default values as a last resort.

6. How is uncertainty handled at early design stages?

The methodology applies mandatory contingency factors that decrease as a project matures: 15 percent at early design, tapering to 6 percent by technical design and construction.

7. How does this relate to RICS V2 or other whole life carbon standards?

Ireland's methodology was informed by several existing frameworks, including the RICS Whole Life Carbon Assessment standard, the IStructE's embodied carbon guidance, and the IGBC's INDICATE methodology, so practitioners familiar with those approaches will recognize much of the underlying logic.

8. Where can I find the official methodology and tools?

SEAI publishes the methodology, the national database, and the calculation workbook on its Life-Cycle Global Warming Potential (GWP) page.

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