What is EN 15804? Understanding Construction EPD Standards (Plus ISO 21930)

If you’re creating or using EPDs for construction products, you’ll encounter two standards that seem to do the same thing: EN 15804 and ISO 21930. Both provide core rules for construction EPDs, yet they’re subtly different. Understanding which standard applies to your market can mean the difference between acceptance and rejection of your EPD.

The confusion is understandable. ISO 21930 was published in 2017, while EN 15804’s latest version came in 2019 with a corrigendum in 2021. They evolved from the same foundation but diverged for practical and political reasons.

EN 15804: The European Construction EPD Standard#

EN 15804 provides the core Product Category Rules for all construction products and services in Europe. Think of it as the master template that ensures every concrete EPD, insulation EPD, or steel EPD follows the same methodology, making them genuinely comparable.

Published initially in 2012, EN 15804 has undergone significant evolution:

• EN 15804:2012 – The original version establishing the framework
• EN 15804:2012+A1:2013 – First amendment adding harmonised impact methods
• EN 15804:2012+A2:2019 – Major revision aligning with EU environmental policy
• EN 15804:2012+A2:2019+AC:2021 – Current version with August 2021 corrigendum

The “+A2” version, mandatory since October 2022, represents a fundamental shift in how construction EPDs handle environmental impacts. The 2021 corrigendum (AC) provided technical corrections and clarifications without changing the fundamental requirements.

What EN 15804 Actually Does#

EN 15804 defines precisely how to conduct Life Cycle Assessments for construction products:

System Boundaries: Which life cycle stages to include and how to define them Impact Categories: What environmental impacts to calculate (climate change, acidification, etc.) Calculation Methods: Specific characterisation factors and models to use (from EC-JRC) Reporting Format: How to present results in the EPD document Comparability Rules: Under what conditions products can be compared Information Modules: How to structure data for aggregation at building level

The standard doesn’t just say “calculate carbon emissions”. It specifies exactly which methodology to use, which emission factors to apply, and how to handle complex situations like recycling or energy recovery.

Companion Standards#

EN 15804 doesn’t work alone. It’s part of a suite of standards for construction sustainability:

• EN 15942 – Communication formats for business-to-business EPD exchange
• CEN/TR 15941 – Methodology for selecting and using generic data
• EN 15978 – How to use EPD data for building-level environmental assessment
• EN ISO 14067:2018 – Carbon footprint calculation (referenced for biogenic carbon)
• EN 16449 – Calculation of biogenic carbon content in wood products

These companion standards ensure EPDs integrate properly into building assessment workflows and maintain consistency across the supply chain.

The Life Cycle Modules#

EN 15804 organises the building life cycle into clear modules:

Product Stage (A1-A3):

• A1: Raw material extraction and processing
• A2: Transport to manufacturer
• A3: Manufacturing

Construction Stage (A4-A5):

• A4: Transport to construction site
• A5: Installation/construction

Use Stage (B1-B7):

• B1: Use
• B2: Maintenance
• B3: Repair
• B4: Replacement
• B5: Refurbishment
• B6: Operational energy use
• B7: Operational water use

End of Life (C1-C4):

• C1: Deconstruction/demolition
• C2: Transport to disposal
• C3: Waste processing
• C4: Final disposal

Module D: Benefits and loads beyond the system boundary

Module D requires special attention in EN 15804+A2. It must account for:

• Net flows leaving the product system (recycling, energy recovery)
• Substitution potential of secondary materials or fuels
• Exported energy based on current average technology
• Elementary flows related to material inherent properties (biogenic carbon content, carbonation potential, net calorific value)

EN 15804+A2 makes reporting Modules C and D mandatory, unlike previous versions that only required A1-A3. This forces transparency about end-of-life impacts and potential benefits.

ISO 21930: The International Alternative#

ISO 21930:2017 serves as the international standard for construction EPDs. It emerged partly because EN 15804’s success demonstrated the need for global harmonisation, and partly because non-European markets needed their own framework.

ISO 21930 mirrors many provisions of EN 15804+A1. In fact, when it was published in 2017, the two standards were largely aligned. Both use the same modular structure, similar impact categories, and comparable methodologies.

But here’s the crucial point: ISO 21930:2017 doesn’t align with EN 15804+A2.

Comparability: The Building Context Requirement#

EN 15804 is explicit about when EPDs can be compared. The fundamental principle: comparison of construction products using EPD information shall be based on the product’s use in and its impacts on the building.

This means you cannot simply compare two insulation products’ EPDs in isolation. The comparison must consider:

• The complete life cycle (all information modules A-D)
• The same functional requirements as defined by legislation or client brief
• The influence on operational aspects of the building
• Any excluded processes, modules or life cycle stages must be identical

For sub-building comparisons (components, assembled systems), the standard maintains strict requirements:

• Environmental and technical performance of excluded items must be identical
• Amounts of excluded materials must be the same
• Elementary flows related to material properties must be considered completely

The standard notes bluntly: “EPD that are not in a building context are not tools to compare construction products.” This prevents misuse of EPDs for simplistic product comparisons outside their intended application.

Key Differences Between the Standards#

While the standards share DNA, important differences affect practical implementation:

Module D Reporting:

• EN 15804+A2: Mandatory
• ISO 21930: Optional

Impact Categories:

• EN 15804+A2: Expanded set including biogenic carbon separation
• ISO 21930: Original set from EN 15804+A1

Allocation Rules:

• EN 15804: Allows allocation to co-products
• ISO 21930: Stricter rules treating outputs as waste

Geographic Focus:

• EN 15804: European methods and databases
• ISO 21930: Flexible for regional adaptation

These differences might seem minor, but they can significantly affect results and comparability.

The EN 15804+A2 Revolution#

The 2019 amendment brought fundamental changes that go beyond technical adjustments:

Biogenic Carbon Accounting#

The biggest change involves how EPDs handle carbon from biological sources. EN 15804+A2 now separates Global Warming Potential into three categories:

• Climate Change – Fossil
• Climate Change – Biogenic (removal and emissions)
• Climate Change – Land use and land use change

This separation provides transparency about where carbon impacts originate. For timber products, this clearly shows carbon storage benefits. For bio-based materials, it prevents greenwashing by tracking the full biogenic carbon cycle.

Critical Rules on Carbon:

• Carbon offset processes are explicitly excluded – “Carbon offset shall not be included in the calculation of the GWP”
• Temporary carbon storage and delayed emissions cannot be discounted
• Permanent biogenic carbon storage shall not be included in GWP calculations
• The standard requires complete tracking of biogenic carbon content, carbonation potential, and net calorific value

These strict rules prevent manufacturers from making misleading claims about carbon neutrality through offsets or temporary storage.

Mandatory End-of-Life Reporting#

Previously, EPDs could report just “cradle to gate” (A1-A3). Now they must include end-of-life scenarios (C1-C4) and Module D. This forces manufacturers to consider and communicate what happens when their product reaches end of life.

Reasonable scenarios must be provided. A steel beam EPD might assume 90% recycling based on current practice. A composite material might assume landfilling if no recycling infrastructure exists.

Additional Environmental Indicators#

EN 15804+A2 expanded the required indicators beyond traditional LCA impacts:

• Particulate matter emissions
• Ionising radiation
• Ecotoxicity (freshwater)
• Human toxicity (cancer and non-cancer effects)
• Land use related impacts
• Water scarcity footprint

These additions reflect growing understanding of environmental impacts beyond climate change.

Characterisation Factors: The standard mandates use of specific characterisation factors from the European Commission Joint Research Centre (EC-JRC). These are available at eplca.jrc.ec.europa.eu and identified by the name “EN_15804”. This ensures all EPDs use identical impact assessment methods.

PEF Alignment (Sort Of)#

The European Commission mandated EN 15804’s revision to align with their Product Environmental Footprint (PEF) methodology. Ironically, PEF hasn’t gained market traction while EPDs have flourished.

The alignment isn’t complete. Significant methodological differences remain, making PEF and EPD results non-comparable despite the attempted harmonisation.

Why Two Standards Exist#

The dual standard situation reflects practical realities:

Regional Needs: European construction markets have specific requirements tied to EU regulations. The Construction Products Regulation (CPR) increasingly references EN 15804.

International Trade: ISO standards facilitate global trade by providing internationally recognised frameworks. Manufacturers exporting globally often need ISO 21930 compliance.

Regulatory Evolution: EN 15804 can update more quickly to meet European regulatory changes. ISO standards move more slowly due to broader consensus requirements.

Technical Preferences: Different regions prefer different impact assessment methods. TRACI is common in North America, while Europe uses EF methods.

Choosing Your Standard: Practical Guidance#

For manufacturers, the choice often isn’t either/or but both/and:

Use EN 15804+A2 When:#

• Selling primarily in European markets
• Meeting CPR requirements
• Working with European green building schemes
• Your competitors use EN 15804 EPDs

Use ISO 21930 When:#

• Targeting global markets
• Exporting outside Europe
• North American markets (often with TRACI methods)
• Your supply chain spans continents

The Dual EPD Strategy#

Many manufacturers now create dual EPDs:

1. EN 15804+A2 version for European compliance
2. ISO 21930 version for international markets

Smart EPD tools can generate both from the same LCA data, adding only verification costs rather than doubling the entire expense.

Regulatory Drivers and Future Requirements#

The regulatory landscape is shifting rapidly:

European Requirements#

The revised Construction Products Regulation (CPR), which entered force in January 2025, mandates environmental information for construction products. By 2026, manufacturers must declare Global Warming Potential. By 2030, full EN 15804-based EPDs become necessary.

The Ecodesign for Sustainable Products Regulation (ESPR) extends similar requirements beyond construction to electronics and systems.

International Developments#

While ISO 21930 hasn’t updated to match EN 15804+A2, pressure is building for harmonisation. Trade barriers emerge when regions require different EPD standards, motivating alignment efforts.

Some countries are developing national variations. The Netherlands’ MKI (Environmental Cost Indicator) system builds on EN 15804 but adds monetisation of impacts.

From Products to Buildings: The Aggregation Framework#

EN 15804 designs EPDs to be building blocks for whole-building assessment. The standard states: “EPD is expressed in a form that allows aggregation (addition) to provide complete information for buildings and other construction works.”

This aggregation capability is why the modular structure matters. Each module’s impacts can be summed across products to calculate building-level impacts. EN 15978 then provides the methodology for using these aggregated EPDs in building environmental performance calculations.

The information modules ensure:

• Consistent data packaging across the life cycle
• Reproducible and comparable results
• Clear allocation of impacts to specific life stages
• Transparent scenarios for future stages

However, EN 15804 itself doesn’t deal with aggregation at building level – that’s handled by EN 15978. This separation keeps product-level and building-level methodologies distinct while ensuring compatibility.

Practical Implementation Challenges#

Creating EPDs under either standard presents challenges:

Data Requirements#

Both standards demand extensive data:

• Material compositions and sources
• Energy consumption by type
• Transport distances and modes
• Manufacturing processes
• Waste generation and treatment

The challenge intensifies with complex products containing dozens of materials from global supply chains.

Software and Databases#

EN 15804 EPDs typically use European databases like Ecoinvent with European energy mixes. ISO 21930 EPDs might use regional databases with local energy data. This affects results and can complicate compliance with both standards.

Verification Complexity#

Each standard has approved verifiers familiar with its specific requirements. A verifier expert in EN 15804+A2’s biogenic carbon rules might not understand ISO 21930’s allocation approaches.

Maintenance Burden#

EPDs expire after five years. With two standards potentially requiring updates at different times with different requirements, maintenance becomes complex and costly.

Making EPDs Work Across Standards#

Despite the challenges, practical solutions exist:

Invest in robust LCA models: A comprehensive model can generate outputs for both standards Document thoroughly: Clear documentation simplifies verification under either standard Plan for updates: Build standard evolution into your EPD strategy Choose compatible tools: Software supporting both standards reduces duplicate work Consider harmonised programmes: ECO Platform members often recognise each other’s EPDs

The Future: Convergence or Continued Divergence?#

The construction industry needs harmonised standards for truly comparable EPDs. Current trends suggest:

Possible ISO Update: ISO 21930 may update to incorporate EN 15804+A2 innovations, particularly biogenic carbon accounting

Digital Integration: Both standards must evolve for machine-readable EPDs and Digital Product Passports

Scope Expansion: From products to assemblies to whole buildings, EPD standards continue expanding

Regional Variations: Despite harmonisation efforts, regional requirements will likely persist

Practical Guidance from Decerna#

At Decerna, we navigate both EN 15804 and ISO 21930 requirements daily, working with the complete suite of companion standards. Our approach:

We start by understanding your markets. European focus? EN 15804+A2:2019+AC:2021 is essential, along with EN 15942 for communication formats. Global ambitions? You’ll need ISO 21930 compatibility. Many clients need both.

We build LCA models that can output to either standard from the same data foundation, using EC-JRC characterisation factors for EN 15804 compliance. This minimises cost while maximising market access. Our EPDs clearly state which standards they follow and include all mandatory modules (A-D for EN 15804+A2).

Critical aspects we ensure:

• No carbon offsets in GWP calculations
• Complete biogenic carbon tracking through all life stages
• Proper Module D calculations including substitution benefits
• Building context considerations for any comparative claims
• Compliance with companion standards for data selection (CEN/TR 15941) and communication (EN 15942)

The standards might be complex, but the goal is simple: credible, comparable environmental data that supports better decisions. Whether through EN 15804 or ISO 21930, EPDs deliver that transparency – when done right.

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Need EPDs that work across multiple markets? Decerna creates EN 15804 and ISO 21930 compliant EPDs that meet both European and international requirements. Contact us to discuss your EPD strategy.