21 August 2026

EF 3.1 and EN 15804+A2: what each one actually does

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, according to the European Commission overview of Environmental Footprint methods. 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

What each one governs

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.

Instrument	Role	What it governs
EF 3.1	Life-cycle impact assessment method	16 impact categories, characterization, and optional normalization and weighting
EN 15804+A2	Construction-product standard	Declaration rules, 13 core indicators, and modules A1–A3 through D
EN 15804 reference package	EF-based package used with EN 15804	Based on EF 3.1, with documented differences such as biogenic CO2 (−1 uptake / +1 release)

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 those 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

Choosing the method package does not change the bill of materials. Materials, transport, energy and packaging stay as they are. What changes is characterization and, where used, normalization.

That is why a method update can move results with no BOM change. The EF 3.0-to-EF 3.1 update introduced new characterization factors for climate change, acidification, freshwater ecotoxicity, photochemical ozone formation, human toxicity cancer and human toxicity non-cancer. Toxicity and ecotoxicity can therefore shift while the inventory is untouched. JRC130796 compared 2,752 official Environmental Footprint datasets and 49 representative products. It does not give a single percentage swing to quote.

Record the package and version. The same BOM can be characterized under the general EF 3.1 method or the EN 15804 reference package; the results are not automatically interchangeable.

A product carbon footprint and an EPD-style table can share that inventory. They are not the same study by default: ISO 14067 PCF work and EN 15804 reporting still differ in rules, indicators and documentation.

Dawn can run that inventory on Ecoinvent-based EF 3.1, EN 15804, or cutoff. The method choice stays with the practitioner.