Until now, how “green” a building is was shown almost only by how much energy it uses in operation. The European Union’s revised Energy Performance of Buildings Directive – EPBD for short, (EU) 2024/1275 – goes further: from 2028 for large new buildings and from 2030 for all new buildings, the carbon dioxide emissions over the whole life cycle must be calculated and shown in the energy performance certificate. Here is a summary of what is changing and what it means if you design with CLT.
What does the life-cycle carbon footprint measure?
The directive’s technical term is life-cycle global warming potential, GWP for short. It shows how much greenhouse gas is released over the entire life of the building: from the production of building materials through construction and operation to demolition.
The calculation rules are set out in Annex III of the directive. This annex has been replaced by Delegated Regulation (EU) 2026/52, in force since 24 May 2026. Under the new annex:
- Unit: kg CO₂ equivalent per square metre of useful floor area (kg CO₂e/m²).
- Reference period: 50 years. This is a calculation convention, not an assumption about the building’s service life.
- Method: the relevant parts of EN 15978.
- What to include: at least the Tier 2 elements of the building’s shell and core, according to Table 4 of the annex. Including external works is optional.
- Mandatory life-cycle stages: A1–A5, B1–B4, B6, C1–C4, D1 and D2. Optional: B5, B7 and B8.
- The certificate shows at least: A1–A3, A4–A5, B1–B4, B6, C1–C4, D1, D2 and the GWP-total, the sum of the fossil and biogenic emissions and the effect of land use.
The value reflects the as-built building. It is still worth calculating during design, because the result can then still be shaped.
In other words, the choice of material – concrete, steel, timber – becomes visible in figures in the rating of a building for the first time.
The timeline
| Date | What happens | In the directive |
|---|---|---|
| 29 May 2026 | member states transpose the directive into national law | Article 35 |
| 1 January 2027 | member states publish a roadmap for introducing life-cycle limit values for new buildings | Article 7(5) |
| 1 January 2028 | life-cycle carbon footprint calculated and shown in the energy performance certificate for all new buildings over 1000 m²; new buildings of public bodies are zero-emission | Article 7(1)–(2) |
| 1 January 2030 | the same for all new buildings; all new buildings are zero-emission; member states set targets | Article 7(1), (2), (5) |
Important exception (Article 7(4)): a member state may decide not to apply paragraphs 1 and 2 to buildings for which an application for a building permit – or an equivalent application, including a change of use – was submitted before the deadline. Whether a country makes use of this option will become clear from its national transposition.
Where does transposition stand? On 15 July 2026 the European Commission opened infringement procedures against all 27 member states for incomplete transposition. The national detailed rules are therefore still taking shape.
What does this mean for design?
The choice of material is made at concept stage. When the structural system is decided, much of the carbon footprint is decided too. That is why it is worth comparing the options from the first sketch – later, changes are expensive and slow.
Exact quantities are needed. A life-cycle calculation is only as accurate as the material quantities. From a detailed 3D model, the volume and mass of the installed materials can be extracted element by element.
The data has an order of priority. The new Annex III sets which environmental data must be used:
- first, data under the Construction Products Regulation (305/2011/EU or (EU) 2024/3110), where available;
- then compatible ecodesign data;
- other product- or project-specific data under EN 15804 – for example an environmental product declaration (EPD) – only where national law expressly allows it;
- generic or default values where gaps have to be filled.
An EPD alone may therefore not be enough: when requesting offers, ask the manufacturer whether environmental data under the Construction Products Regulation exist for the product, and clarify what the national calculation method accepts.
The roof is also for solar energy. Under the directive, every new building must be designed so that solar energy can later be used cost-effectively; installing solar panels also becomes mandatory step by step where the building is technically suitable and installation is economically and functionally feasible (Article 10): by 31 December 2026 for new public and non-residential buildings, with a 250 m² useful floor area threshold (whether the threshold also applies to public buildings reads differently across the language versions of the directive; national transposition will clarify this), and by 31 December 2029 for new residential buildings. The roof structure must therefore also be designed for the load of solar panels.
Where does CLT come in?
How much better the carbon footprint of a CLT building is than that of another structure is determined building by building – that is exactly what the life-cycle calculation is for. But three things are already clear:
- Timber binds carbon. The amount of carbon dioxide stored in the installed timber can be calculated with a standard method (EN 16449). How the life-cycle calculation takes this into account is determined by the standard and the national calculation method.
- The biogenic part also appears in the certificate. The GWP-total to be shown includes the biogenic part and the effect of land use alongside fossil emissions.
- The directive addresses carbon stored in buildings. Article 7(6) requires member states to address carbon removals associated with carbon storage in or on buildings.
The national calculation method and the limit values depend on national transposition. Switzerland is not an EU member, so the directive does not apply there directly. We follow the developments and will update this article.
What should you do now?
- Handover after 2028, over 1000 m²? Expect the life-cycle carbon footprint to be calculated and shown in the certificate – based on the as-built state.
- Check the date of the permit application. A member state may make an exception for applications filed before the deadline; whether it applies to you depends on national rules.
- Compare the structural system at concept stage – that is where it is cheapest to decide between CLT, hybrid and conventional solutions.
- Request environmental data for the main materials already when requesting offers: first data under the Construction Products Regulation, and also ask about an EPD under EN 15804.
- Design with an accurate model and track changes in it, so that the quantities are reliably available at handover.
How we help
At concept stage we compare the structural options, and from the 3D model prepared for the fabrication drawings we provide the volume and mass of the installed timber element by element – one of the most important inputs for the life-cycle calculation. We also calculate the carbon dioxide stored in the installed timber – this is how we calculate it. We design the roof structure for the load of solar panels, and when comparing manufacturers’ offers, we also request the environmental data.