EN 15804+A2 Modules Explained, from A1-A3 to Module D

EN 15804+A2 splits the life of a construction product into modules, from raw material supply (A1) to benefits beyond the system boundary (D). Knowing which modules are mandatory, what goes into each and how they are reported is the first step in planning an EPD or reading one correctly. This article sets it out with a module table, the indicator list and the mistakes we see most often in A2 EPDs.

What the EN 15804+A2 modules are

EN 15804+A2 modules are standardised blocks of a construction product's life cycle used to report EPD results. They group processes into the product stage (A1-A3), construction process stage (A4-A5), use stage (B1-B7), end-of-life stage (C1-C4) and module D, which covers reuse, recovery and recycling potential beyond the system boundary.

The same structure is used in EN 15978 for whole-building assessment, which is why EPD results can be dropped into a building LCA module by module. The modularity principle in EN 15804 says that processes are assigned to the module where they occur, so impacts are not shifted between stages.

The module table

Which modules are mandatory under A2

The biggest change from the A1 version is that end of life is no longer optional. Under A2, modules A1-A3, C1-C4 and D must be declared for nearly every construction product. Only a product that meets all three of the following conditions may publish a cradle-to-gate EPD covering A1-A3 alone.

1. It is physically integrated with other products during installation, so it cannot be physically separated from them at end of life.
2. It is no longer identifiable at end of life because of a physical or chemical transformation.
3. It contains no biogenic carbon.

Cement, screeds and some adhesives can qualify. Steel sections, tiles, glass, insulation boards and aluminium profiles cannot, because they remain identifiable and are routinely removed, recycled or landfilled. Modules A4, A5 and B1-B7 stay optional, although some c-PCRs and many buyers expect A4 and A5.

Product stage A1-A3 in practice

A1-A3 is where plant data matters most, and for most products it carries the bulk of the GWP. EN 15804 allows A1, A2 and A3 to be reported as one aggregated A1-A3 figure, and most EPDs do so. For cement, calcination and kiln fuel dominate. For aluminium profiles, the origin of the billet usually outweighs extrusion and finishing combined.

Electricity modelling sits here too. The PCR decides when you may use contractual instruments such as guarantees of origin (in Turkey, YEK-G certificates) and when the national grid or residual mix applies, and that choice can shift A1-A3 GWP considerably for electricity-intensive products.

Construction process stage A4-A5

A4 is often requested for exported products because the transport leg is significant. A product shipped from Turkey to a site in northern Europe may travel by truck to a port, by sea and again by road. Programme rules expect the scenario to be stated clearly, with distance, vehicle type and load factor, so building LCA users can replace it with their own.

A5 covers installation losses and packaging waste. A detail that verifiers check is biogenic carbon in timber pallets and paper packaging, which is taken up in A1-A3 and has to be released again in A5 so that the balance closes.

Use stage B1-B7

Most product EPDs leave B modules undeclared or report zero, because maintenance and replacement depend on the building. Exceptions are products with a measurable use-stage effect, such as concrete carbonation in B1, coatings with a repainting cycle in B2 or equipment with energy use in B6. When B modules are declared, a reference service life (RSL) must be stated and justified.

End of life C1-C4

End-of-life scenarios describe what happens after demolition, for example 85 per cent of steel recovered for recycling and the rest landfilled. They should reflect the market where the product is used and be supported by statistics or sector data. For Turkish manufacturers selling across the EU, we usually model one representative European scenario and state it clearly, since country-specific rates differ widely.

Module D and why it is reported separately

Module D shows the potential net benefit of recycling or recovering material after the end-of-waste state, for example scrap steel replacing primary steel. It is always reported separately and must not be added to A-C results as a single total. Only net flows count, so a product made with high recycled content gets a smaller module D credit than one made from primary material. Users of the EPD decide whether and how to include D in their building assessment.

Declared unit, functional unit and reference service life

The modules you declare also decide which unit you report against. A cradle-to-gate EPD with C1-C4 and D, the most common type, uses a declared unit such as 1 tonne, 1 kg or 1 m² of product. It describes the product without fixing how it performs in a building. An EPD that covers the full life cycle, including the B modules, needs a functional unit that describes the function delivered over a reference service life, for example 1 m² of external wall insulation with a given thermal resistance over 50 years.

The reference service life (RSL) is required whenever B modules are declared, and it must be justified with test data, standards or sector references. For products sold into several markets, a declared unit is usually the safer choice, since the building LCA practitioner then applies the service life and use conditions of the actual project.

Indicators declared for each module

Under A2, results are reported per module for the following impact indicators. The 13 core indicators are mandatory, and the 6 additional ones are reported where the PCR or programme requires them. The same 19 indicators appear in Annex II of the Construction Products Regulation (EU) 2024/3110.

Alongside these, EPDs report resource use (primary energy, secondary materials, fresh water), waste categories and output flows such as materials for recycling and exported energy. Some indicators, including abiotic depletion, water deprivation, ecotoxicity, human toxicity and land use, carry a mandatory disclaimer because their results are still considered uncertain.

Common mistakes in A2 EPDs

• Declaring A1-A3 only for a product that does not meet all three exemption conditions
• Generic end-of-life scenarios that do not match the target market, with no source given
• Module D credits claimed for recycled content that entered the system as scrap, so the credit is counted twice
• Biogenic carbon in packaging taken up in A1-A3 but not released in A5
• Electricity modelled with certificates that do not meet the PCR's quality criteria
• Comparing A2 results directly with older A1 EPDs, which used different impact methods

Getting these right at the scoping stage saves verification rounds. Our EN 15804+A2 EPD service for construction products covers modules, scenarios and c-PCRs for each product group, and our guide on what an EPD is covers the basics. For the full process from PCR to publication, see EPD consultancy and development.