EN 15804 — The Definitive Reference

EN 15804 Is the Core Rules, the PCR Is the Recipe, the EPD Is the Result

The single most useful framing for EN 15804 is that it is not, by itself, an Environmental Product Declaration, and it does not produce a carbon number for any specific product. It is the set of core rules that every construction-product EPD in Europe must follow — the common grammar that makes one declaration comparable to another. Three distinct artefacts are routinely conflated, and separating them resolves most of the confusion practitioners run into.

EN 15804 is also strictly a product-level standard. Its sister standard, EN 15978, assembles individual product EPDs into a whole-building life-cycle assessment. The relationship is hierarchical: EN 15804 governs the brick, the beam and the insulation board; EN 15978 governs the building they form. A product EPD is an input to a building LCA, not a substitute for one.

Historical Context and Version Timeline

EN 15804 has moved from a flexible 2012 standard with optional end-of-life reporting to a far stricter A2 regime with mandatory cradle-to-grave modules, split climate indicators and rigorous biogenic-carbon accounting. The transition has not been cosmetic: EPDs produced under the older +A1 rules are generally not comparable with +A2 declarations, which is why version tracking matters.

The current construction-products PCR in the International EPD System, PCR 2019:14 version 2.0.1, was published on 5 June 2025 and is valid until 7 April 2030. It complies with General Programme Instructions (GPI) version 5 and references EN 15941:2024 for data quality. The previous version, 1.3.4, expired on 20 June 2025, with a short parallel window from the 2.0.0 release. EPDs verified before that window may still cite earlier 1.3.x versions until they reach the end of their five-year validity.

The Standards Stack — Where EN 15804 Sits

GreenCalculus applies the EN 15804 module factors throughout its element-level embodied-carbon methodologies — for concrete and cement, steel and aluminium, timber and bio-based materials, masonry and finishes, the building envelope, and plastics and packaging — then aggregates them to building scale in the whole-building LCA methodology. The sector Product Category Rules these declarations follow are set by the ISO 21930 construction-EPD core rules.

EN 15804 does not stand alone. It inherits its methodology from the ISO life-cycle-assessment standards, operates as a Type III declaration under ISO 14025, and feeds upward into building-level assessment. Understanding the stack prevents the common mistake of treating EN 15804 as a self-contained calculation method.

The Life-Cycle Module Structure (A–D)

The module structure is the heart of EN 15804 and the source of most misreadings. The standard divides a product’s life cycle into labelled modules grouped into four stages — Product (A1–A3), Construction (A4–A5), Use (B1–B7) and End of life (C1–C4) — plus a separate Module D for benefits and loads beyond the system boundary. Under +A2, the mandatory minimum scope for a construction-product EPD is A1–A3, C1–C4 and D; the A4–A5 and B modules are declared where the PCR or scenario requires.

Cradle-to-gate vs cradle-to-grave

An EPD declaring only A1–A3 is “cradle-to-gate”: it stops at the factory gate and says nothing about transport, installation, use or disposal. An EPD declaring A1–A3 plus C1–C4 and D, with construction and use modules as applicable, approaches “cradle-to-grave”. The two are not interchangeable. A cradle-to-gate A1–A3 figure is a legitimate, useful number — but presenting it as a product’s whole-life footprint is one of the most common misrepresentations in the market.

Why modules cannot simply be added together

The modules are reported separately and are not designed to be summed into a single headline number without care. Module D in particular sits outside the system boundary and represents potential future credits and loads — it is not subtracted from A–C to produce a flattering net figure. Whole-building assessment under EN 15978 aggregates modules according to defined rules, scenarios and a consistent system boundary; lifting individual module values from a product EPD and adding them ad hoc produces results that do not reconcile and fail verification.

Declared Unit, Reference Service Life and Scenarios

Three modelling choices determine whether two EPDs can actually be compared, and all three are common sources of apparent — but spurious — differences between products.

Declared unit vs functional unit

Most product EPDs use a declared unit — a physical quantity such as 1 kg, 1 m³, or 1 m² of product — because the product’s final function depends on how it is used in a building, which the manufacturer cannot know in advance. A functional unit, by contrast, expresses performance (for example, “one square metre of wall providing a given thermal resistance for 60 years”). Whole-building LCA needs functional units; product EPDs typically provide declared units. Converting from one to the other — accounting for quantity, service life and replacement — is a frequent error point, because two products with similar per-kilogram numbers can diverge sharply once required quantities and replacement cycles are applied.

Reference service life and the B modules

The use-stage modules (B1–B7) depend on an assumed reference service life (RSL). How long a product lasts before replacement drives B4 (replacement) and, through the building model, the number of replacement cycles over the building’s life. RSL assumptions are a major comparability weak point: a product credited with a long service life carries fewer replacement burdens than an identical product modelled with a shorter one. EPD readers should check the declared RSL and the basis for it before comparing use-stage numbers.

End-of-life scenarios

The C modules and Module D rely on declared end-of-life scenarios — assumptions about what happens to the product at the end of its life (landfill, incineration with energy recovery, recycling, reuse). EN 15804+A2 requires realistic, transparent scenarios even where market routes are still maturing. Optimistic recycling assumptions can materially lower C-module and improve Module D figures, so scenario plausibility is exactly where reviewers concentrate scrutiny.

The +A2 Impact Indicators

EN 15804+A2 expanded the core environmental indicators well beyond climate change, and — most importantly for carbon accounting — split global warming potential into separate categories. The headline figure most teams read first is GWP-total, but the sub-splits are where reviewers check credibility, particularly for bio-based materials.

The four climate-change categories

The GWP-GHG carry-over indicator

Alongside the four +A2 climate categories, the International EPD System made GWP-GHG an additional mandatory indicator under GPI 5. GWP-GHG is, in effect, the comparability bridge back to the older +A1 world: it is broadly the single GWP indicator used under +A1, with the difference that characterisation factors are drawn from a more recent IPCC assessment. Where a specifier needs to compare a current +A2 declaration with legacy +A1 data, GWP-GHG is the indicator that makes that comparison least unreliable — though it is still not a perfect bridge, because the underlying PCRs, units and module scopes differ.

Beyond climate — the wider indicator set

The +A2 core set extends to roughly thirteen impact indicators, covering ozone depletion (kg CFC-11 eq), acidification (mol H⁺ eq), eutrophication (freshwater, marine and terrestrial), photochemical ozone formation, abiotic resource depletion (minerals/metals and fossil), and water use, alongside resource-use, waste and output-flow indicators. A credible EPD reports the full set; a carbon number presented in isolation, without the surrounding indicators, is an incomplete declaration.

Biogenic Carbon Treatment

Biogenic carbon is the single most significant — and most misread — change introduced by +A2. The standard requires the full life of biogenic carbon to be traceable, separating the carbon taken up during biomass growth from the carbon released at end of life. The aim is to prevent bio-based products from appearing artificially clean by counting only the uptake and ignoring the eventual release.

The uptake / release convention

Two prohibitions that protect integrity

EN 15804+A2 is explicit on two points that buyers frequently misunderstand. First, carbon offsets must not be included in the calculation of GWP — an EPD cannot net purchased credits against its declared impacts. Second, temporary carbon storage and delayed emissions must not be credited — a product cannot claim a benefit simply for holding carbon for a period before releasing it. Both rules exist to stop the declared number being inflated by mechanisms that do not represent a real, durable reduction. Packaging biogenic carbon must also be declared, closing a route by which carbon could otherwise be hidden.

Allocation, Cut-off and Module D Credit

Two compliant EPDs for genuinely identical products can still differ because of methodological choices the standard permits within bounds. Allocation and cut-off are where that latitude lives, and where a careful reader checks for credibility.

PCRs, Versions and Comparability

EN 15804 sets the core rules, but a Product Category Rule (PCR) translates those rules into product-specific instructions: which modules to declare, what declared unit to use, what scenarios to assume. For construction products in the International EPD System, the workhorse PCR is 2019:14. Sub-PCRs (c-PCRs) refine the rules for specific product families — concrete, insulation, photovoltaic components and many others — and are used in addition to the main PCR.

EPD Types, Data Quality and Verification

Not all EPDs carry equal weight in a building LCA, even when all are EN 15804-compliant. The representativeness of the underlying data is what distinguishes a product-specific declaration from a generic one, and reviewers treat them very differently.

Verification, validity and re-issue

Every EN 15804 EPD is a Type III declaration verified by an independent third party against the relevant PCR before publication under ISO 14025. Verification can be EPD-by-EPD or through a process certification covering a manufacturer’s EPD-generation system. EPDs are typically valid for five years. Programme operators expect an EPD to be updated within that window if a published indicator worsens beyond a defined margin — commonly cited as around a 10 per cent deterioration — which acts as a practical trigger after a plant change or reformulation.

From Product EPD to Whole-Building LCA and Scope 3

EN 15804’s purpose is not to produce a standalone marketing number but to feed structured, comparable data into larger assessments. Two consumers of that data matter most: building-level LCA under EN 15978, and corporate value-chain accounting under the GHG Protocol.

In a whole-building assessment, each material’s A1–A3 figures (and, where modelled, A4–D) are scaled by the quantity of material in the building and combined according to EN 15978 rules to produce the building’s embodied-carbon profile. This is also where declared units must be converted to the building’s functional unit, and where reference service life drives replacement cycles. Errors in that conversion — not in the EPDs themselves — are a leading cause of unreliable whole-building numbers.

For corporate reporting, EN 15804 EPD data flows into Scope 3 accounting. A construction firm’s purchased materials sit in Category 1 (purchased goods and services); capital construction assets sit in Category 2 (capital goods). High-quality, product-specific EPDs are the supplier-specific primary data that the Scope 3 calculation hierarchy ranks above spend-based estimates. The same embodied-carbon factors that the GreenCalculus materials library derives from EN 15804-based EPD datasets are what make activity-based Scope 3 Category 1 and 2 calculations possible. EPD-derived data also underpins material declarations relevant to the EU CBAM for carbon-intensive imported materials.

Regulatory and Market Drivers

EN 15804 EPDs are shifting from a voluntary marketing asset to a phased regulatory requirement, driven principally by the revised EU Construction Products Regulation and reinforced by green-building schemes and disclosure regimes.

Worked Illustration — Biogenic Reversal Across Modules

The illustration below is a deliberately simplified, schematic sketch — not values from any specific product EPD — to show why reading only the cradle-to-gate figure misleads for bio-based materials. The numbers are illustrative placeholders chosen to demonstrate the sign behaviour, not factors to be cited.

Common Errors That Fail Verification

Frequently Asked Questions