21 August 2026

EF 3.1 Method vs EN 15804+A2: A Practical Guide

EF 3.1 and EN 15804+A2 are related but serve different purposes: EF 3.1 supplies life-cycle impact assessment models and characterization factors, while EN 15804+A2 defines rules for modeling and reporting construction-product environmental declarations. They are complementary choices, not interchangeable alternatives, according to the European Platform on Life Cycle Assessment.

Diagram showing EF 3.1 impact assessment models alongside EN 15804+A2 construction-product reporting rules

What is the EF 3.1 method?

The Environmental Footprint methods are intended to measure and communicate the life-cycle environmental performance of products and organizations. EF 3.1 translates inventory flows from a life cycle assessment—such as emissions, resource consumption and land or water use—into environmental impact results.

EF 3.1 covers 16 impact categories, including climate change, toxicity, freshwater ecotoxicity, water use, land use, eutrophication, acidification and resource use. This multicategory scope is why EF 3.1 should not be treated as another name for a carbon footprint. Carbon is one result within the wider study; Dawn explains the difference between an LCA and a carbon footprint.

EN 15804+A2 includes 13 core environmental impact indicators, in addition to required information about resources, waste and output flows. The difference in counts reflects different assessment and reporting structures, not simply a shorter version of the same list. The figures come from the European Commission’s EF method overview and an EN 15804 reporting guide.

Comparison showing 16 EF 3.1 impact categories and 13 EN 15804+A2 core environmental impact indicators

EF 3.1 versus EN 15804+A2

The current EN 15804 reference package is based on EF 3.1, but it is not identical to the general EF 3.1 package. EN 15804 adds construction-product modeling and reporting rules, including results organized into product, construction, use, end-of-life and beyond-system-boundary modules.

Selection criterion	EF 3.1	EN 15804+A2
Primary role	Life-cycle impact assessment models and characterization factors	Modeling and reporting rules for construction-product declarations
Impact structure	16 impact categories	13 core environmental impact indicators plus resource, waste and output-flow information
Reporting structure	Multicategory environmental results	Modules A1–A3, A4–A5, B1–B7, C1–C4 and Module D
Product scope	Products and organizations	Construction products
Relationship	General Environmental Footprint package	Reference package based on EF 3.1, with specific differences
Selection trigger	Intended assessment and communication purpose	Applicable construction-product rules and program-operator requirements

One documented difference concerns biogenic carbon. The EN 15804 reference package applies a biogenic CO₂ characterization factor of −1 for uptake and +1 for release, as specified in the European Commission’s EN 15804 reference-package documentation. That is one reason results calculated with the general EF package should not automatically be substituted for EN 15804 results.

EN 15804+A2 also separates climate-change reporting into fossil, biogenic and land-use or land-use-change components. Under the International EPD System’s current default list, GWP-GHG is an additional mandatory indicator alongside the EN 15804+A2 core climate indicators, producing five listed GWP figures. Program-specific requirements therefore need to be checked rather than inferred from the method name alone.

Characterization, normalization and weighting

Characterization converts inventory flows into results for individual impact categories. EF results can then be normalized, weighted and aggregated into an overall score, although category-level results remain important for interpretation. The JRC’s EF 3.1 update report cautions against reducing interpretation to the aggregated result alone.

Normalization places category results against reference values so their relative scale can be considered. Weighting applies category-level weighting before aggregation. These steps answer a different question from characterization and should not be confused with the underlying inventory calculation. Teams should retain the individual category results so that a combined score does not conceal a material trade-off between climate, toxicity, water or resource impacts.

The EF 3.0-to-EF 3.1 update introduced new characterization factors for 6 impact categories and new normalization factors for 8 impact categories. The JRC comparison examined 2,752 official Environmental Footprint datasets and 49 representative products, according to the EU publication record and the JRC report.

Statistics showing six categories with new characterization factors, eight with new normalization factors, 2,752 datasets and 49 representative products

The changed characterization factors covered climate change, acidification, freshwater ecotoxicity, photochemical ozone formation, human toxicity cancer and human toxicity non-cancer. Climate-change factors were updated using IPCC 2021 data, while other changes included corrected flows, harmonized data sources and revised factors for inorganic substances, as detailed in the EF 3.1 data guide addendum.

A method update can therefore change a product’s results even when its bill of materials is unchanged. The inventory may contain the same materials, transport, energy and packaging, but revised characterization or normalization factors alter how those flows become impact results. Comparisons should record the method package and version used.

Does EF 3.1 mean a study is PEF-compliant?

No. Selecting EF 3.1 as the impact-assessment method does not by itself establish that a study follows every Product Environmental Footprint modeling, data-quality and reporting requirement. Method selection controls part of the calculation; it does not resolve scope, data quality, product-category rules or reporting obligations.

The same principle applies to construction-product reporting. Applicable product-category rules and program-operator requirements should be checked before modeling because choosing EF 3.1 does not determine every required reporting indicator. Use this sequence:

Decision flow from intended output and sector through product-category rules, program requirements and method selection

The International EPD System’s transition from EF 3.0 ended on August 31, 2024, with its applicable default list requiring EF 3.1-based characterization factors from September 1, 2024. That date belongs to the International EPD System transition; it should not be presented as a universal global deadline.

Applying EF 3.1 to a manufacturer’s BOM

A manufacturer might begin with material quantities, transport legs, utility consumption and packaging. Those inputs form the product inventory. The chosen impact method then translates the inventory into climate, toxicity, water, land, resource-use and other category results.

Dawn is a serious option when that model needs to remain connected to a changing product structure. Teams can manage BOM variants and versions, run product LCAs on Ecoinvent-based databases using EF 3.1, EN 15804 or cutoff, and review hotspots, life-cycle stages and kg CO2e in the resulting impact report.

The product carbon footprint is the carbon result of the same LCA study rather than a separate project. Teams can reuse the impact report to prepare EPD-style impact tables, but method choices, missing primary data and verifier discussions remain human responsibilities. Verification takes place outside Dawn.

Dawn is most relevant where the requirement extends beyond modeling one study: keeping the BOM-based LCA current, collecting supplier evidence and reusing results across carbon numbers and product documentation. Supplier data can be collected through lists, mapping, collection sessions, a public input link and agent-driven email follow-ups. Teams can also maintain product and supplier data in the same system.

Selection verdict

Choose the general EF 3.1 method when the intended output is a multicategory Environmental Footprint assessment and the applicable rules support it. Use EN 15804+A2 when construction-product declaration rules apply, selecting the corresponding reference package and reporting modules rather than assuming general EF 3.1 results are equivalent.

Before calculation, confirm the intended output, sector, product-category rules, program operator, required indicators and method version. For recurring manufacturer studies, also evaluate whether the software can preserve BOM variants, supplier inputs and method-version history after the first model is complete. If that ongoing model is the priority, consider booking a Dawn demo.

FAQ

How do I choose between EF 3.1 and EN 15804+A2?

Start with the intended output and sector. EF 3.1 provides general Environmental Footprint impact models. EN 15804+A2 defines construction-product modeling and reporting rules. Applicable product-category and program-operator requirements take precedence over a general method preference.

Does EF 3.1 cover more than carbon emissions?

Yes. EF 3.1 covers 16 categories, including climate change, toxicity, ecotoxicity, water, land, resource use, eutrophication and acidification. Review the units used by LCA impact indicators when interpreting category results.

Can I compare EF 3.0 and EF 3.1 results directly?

Use caution. EF 3.1 changed characterization factors for six categories and normalization factors for eight. Results can change without an inventory change, so comparisons should identify the method version and package used.

Is selecting EF 3.1 enough to follow the complete PEF framework?

No. EF 3.1 method selection does not establish compliance with every PEF modeling, data-quality and reporting requirement. Use an EF 3.1 alignment checklist and confirm the applicable category rules.

How should EF 3.1 be implemented for a changing product?

Maintain materials, transport, utilities and packaging against a versioned BOM; collect missing supplier data; assign the correct method package; and rerun the study when the inventory or method changes. Preserve individual impact-category results rather than relying only on an aggregated score.