EN 15804 vs ISO 21930: What’s the Difference?

Please note: This article is for educational purposes only. It does not replace the ISO and EN standards. If you work at a university, you probably already have a licence to view the complete standards. If not, please go to your relevant national provider of standards.

When developing Environmental Product Declarations (EPDs) for construction products, manufacturers face a critical choice between two seemingly similar standards: EN 15804 and ISO 21930. Both provide core rules for construction EPDs, yet their differences significantly impact market access, verification requirements, and even the environmental results reported.

This comprehensive comparison explains why two standards exist, their key technical differences, and how to choose the right approach for your markets.

Why Are There Two Standards for Construction EPDs?#

The existence of parallel standards for construction EPDs often confuses newcomers to the field. Surely one international standard would be simpler? The reality reflects the complex interplay between regional regulation, international trade, and the evolution of environmental assessment methods.

EN 15804 emerged first in 2012 from the European need to harmonise construction product environmental declarations across member states. The Construction Products Regulation required consistent methods for environmental assessment, and EN 15804 provided this framework. Its success demonstrated the value of standardised EPDs, prompting international interest in a global equivalent.

ISO 21930 was developed partly in response to EN 15804‘s success and partly from the practical need for non-European markets to have their own framework. When published in 2017, ISO 21930 largely aligned with the then-current version of EN 15804 (specifically EN 15804:2012+A1:2013). Both standards used the same modular structure, similar impact categories, and comparable approaches to life cycle assessment.

However, in 2019, EN 15804 underwent a major revision (the +A2 amendment) that fundamentally changed how it handles biogenic carbon, what environmental impacts must be reported, and which life cycle stages are mandatory. ISO 21930 hasn’t been updated to match these changes, creating the divergence we see today. Table 1 summarises the essential differences between the current versions.

Aspect	EN 15804:2012+A2:2019	ISO 21930:2017
Geographic scope	Europe (mandatory)	International
Life cycle coverage	All modules mandatory	Only A1-A3 mandatory
Biogenic carbon	Separated into 3 categories	Combined in total GWP
Module D	Mandatory reporting	Optional
Impact methods	EC-JRC factors only	Regional methods allowed
Data requirements	Stricter specific data	More flexibility
Verification	ECO Platform mutual recognition	Programme-specific
Water scarcity	Mandatory indicator	Optional
Update alignment	With EN 15804+A2 (2019)	With EN 15804+A1 (2013)

The Historical Context: From Alignment to Divergence#

Understanding how these standards developed helps explain their current differences. Initially, the standards were quite similar – ISO 21930:2017 was deliberately aligned with EN 15804 as it stood in 2013. The divergence came later, driven by European regulatory evolution.

Table 2 shows the key milestones in both standards’ development. Note how ISO 21930 aligned with EN 15804+A1, but hasn’t yet updated to match the significant changes in EN 15804+A2.

Year	Development	Significance
2012	EN 15804 published	First harmonised construction EPD standard
2013	EN 15804+A1 amendment	Added impact assessment methods
2017	ISO 21930:2017 published	Aligned with EN 15804+A1
2019	EN 15804+A2 amendment	Major revision, biogenic carbon separation
2021	EN 15804 corrigendum	Technical corrections
2022	EN 15804+A2 mandatory	Replaced all previous versions in Europe
2025+	ISO 21930 revision expected	Possible alignment with +A2

The regulatory landscape also differs significantly between regions. European markets operate under the Construction Products Regulation (CPR) and emerging requirements from the EU Taxonomy and Green Deal. These regulations increasingly reference EN 15804 specifically. Meanwhile, international markets rely on ISO standards for trade facilitation and compatibility with global green building schemes like LEED.

The Cost of Standardisation#

While these standards are vital for creating EPDs correctly, they are not free and have significant costs to purchase (though prices vary depending on which approved vendor is used). The high costs exist because organisations like ISO and CEN require funding for operational costs. Interestingly, the committees and authors of the standards are volunteers who give up their time to write the documents – it is simply the publishing and maintenance infrastructure which has substantial costs to operate. This article provides comprehensive guidance to help understand which standard you need before making that investment.

Core Methodological Differences#

The most fundamental difference between EN 15804 and ISO 21930 lies in what information must be reported. EN 15804+A2 requires complete life cycle coverage – from raw material extraction through end-of-life and beyond. ISO 21930 takes a more flexible approach, mandating only the production stage while leaving other life cycle stages optional.

This philosophical difference has profound practical implications. An EN 15804 EPD tells the complete environmental story of a product, forcing manufacturers to consider and report what happens during installation, use, and disposal. An ISO 21930 EPD can focus solely on “cradle to gate” impacts, which simplifies development but provides less information for decision-making.

Life Cycle Module Requirements#

Table 3 shows which life cycle modules each standard requires. The difference is stark: EN 15804+A2 mandates all modules, while ISO 21930 requires only A1-A3.

Life Cycle Module	EN 15804+A2	ISO 21930	Impact of Difference
A1-A3 Production	Mandatory	Mandatory	Comparable baseline
A4 Transport to site	Mandatory	Optional	EN provides fuller picture
A5 Installation	Mandatory	Optional	Installation waste included in EN
B1-B7 Use stage	Mandatory scenarios	Optional	Maintenance/replacement in EN
C1-C4 End of life	Mandatory	Optional	Recycling/disposal transparent in EN
Module D Beyond boundary	Mandatory	Optional	Recycling credits clear in EN

This fundamental difference means EN 15804 EPDs always provide complete life cycle information, while ISO 21930 allows partial “cradle to gate” declarations.

Scenario Development Requirements#

For the life cycle stages beyond manufacturing, both standards require scenarios – but again, EN 15804 makes these mandatory while ISO 21930 leaves them optional. Table 4 summarises what scenarios must be developed under each standard.

Scenario Aspect	EN 15804+A2	ISO 21930
Transport distances	Required for A4	If A4 included
Installation waste	Specific rates required	If A5 included
Service life	RSL mandatory	RSL if B modules included
Maintenance cycles	Defined schedules	If B2 included
End-of-life routes	Current practice required	If C modules included
Technology basis	Current average	Current or projected

Biogenic Carbon: A Fundamental Divergence#

Perhaps no difference between the standards is more significant than their treatment of biogenic carbon – carbon from biological sources like timber, bamboo, or agricultural products. This divergence fundamentally affects how bio-based products communicate their environmental credentials.

EN 15804+A2 introduced a revolutionary approach: separate reporting of fossil and biogenic carbon. This means the carbon stored in timber appears as a negative emission (removal from atmosphere) when the tree grows, and a positive emission when the wood eventually decomposes or burns. The net effect over the full life cycle is zero for sustainably managed forests, but the separation provides transparency about timing and carbon storage benefits.

ISO 21930 takes the traditional approach of combining all carbon emissions into a single Global Warming Potential value. While programmes may allow separate reporting of biogenic carbon as additional information, there’s no standardised method for doing so.

Carbon Accounting Comparison#

Table 5 illustrates how differently the standards handle various types of carbon emissions and removals.

Carbon Type	EN 15804+A2 Treatment	ISO 21930 Treatment
Fossil CO₂	Separate (GWP-fossil)	Combined in total
Biogenic CO₂ removal	Separate negative value	Combined or noted
Biogenic CO₂ emission	Separate positive value	Combined or noted
Land use change	Separate (GWP-luluc)	Combined if included
Total reporting	Sum of three categories	Single GWP value
Transparency	Full carbon flows visible	Limited visibility

Practical Impact for Bio-based Products#

The difference becomes clear when comparing how a timber product’s EPD would look under each standard. Table 6 shows the striking difference in how the same CLT panel would be reported.

Product Stage	EN 15804+A2 Reporting	ISO 21930 Reporting
A1-A3 Production	GWP-biogenic: -800 kg CO₂/m³	Note: “Stores carbon”
Module C End-of-life	GWP-biogenic: +800 kg CO₂/m³	Included in total if reported
Net biogenic	Zero (sustainable forestry)	Not explicitly shown
Marketing message	Clear carbon storage benefit	Less standardised

Critical Carbon Rules Comparison#

Both standards also establish important rules about what cannot be included in carbon calculations. Neither allows carbon offsets or credits for temporary carbon storage, but EN 15804+A2 is more explicit and comprehensive in its prohibitions, as shown in Table 7.

Rule	EN 15804+A2	ISO 21930
Carbon offsets	Explicitly prohibited	Generally excluded
Temporary storage credit	Prohibited	Not credited
Delayed emissions	No discounting	No discounting
Biogenic content declaration	Mandatory at factory gate	Optional
Carbonation potential	Mandatory for cementitious	Optional

Environmental Impact Categories#

Beyond carbon, the standards differ significantly in what environmental impacts must be assessed and reported. EN 15804+A2 expanded its requirements considerably, adding indicators for water scarcity, separating eutrophication into three categories, and requiring reporting of additional toxicity and particulate matter indicators.

ISO 21930 maintains a more traditional set of impact categories, with regional programmes able to choose which specific methods to apply. This flexibility allows adaptation to local priorities but reduces comparability between EPDs from different programmes.

Mandatory Impact Categories Comparison#

Table 8 shows which impact categories are mandatory under each standard. Note how EN 15804+A2 requires more indicators and specifies exact methods, while ISO 21930 allows programme flexibility.

Impact Category	EN 15804+A2	ISO 21930	Units Difference
Climate change – fossil	✓ Separate	Combined	kg CO₂ eq
Climate change – biogenic	✓ Separate	Combined	kg CO₂ eq
Climate change – land use	✓ Separate	Combined	kg CO₂ eq
Ozone depletion	✓ Mandatory	✓ Mandatory	kg CFC-11 eq
Acidification	✓ Mandatory	✓ Mandatory	mol H+ eq vs varies
Eutrophication – freshwater	✓ Mandatory	Programme choice	kg P eq vs varies
Eutrophication – marine	✓ Mandatory	Programme choice	kg N eq vs varies
Eutrophication – terrestrial	✓ Mandatory	Optional	mol N eq
Photochemical ozone	✓ Mandatory	✓ Mandatory	kg NMVOC eq
Abiotic depletion – elements	✓ Mandatory	✓ Mandatory	kg Sb eq
Abiotic depletion – fossil	✓ Mandatory	✓ Mandatory	MJ
Water scarcity	✓ Mandatory	Optional	m³ world eq

Additional Environmental Indicators#

EN 15804+A2 also introduced a set of additional indicators that must be calculated and may be declared. These address emerging environmental concerns like particulate matter emissions and human toxicity. Table 9 summarises these additional indicators.

Indicator	EN 15804+A2 Status	ISO 21930 Status
Particulate matter	Declared with disclaimer	Programme option
Ionising radiation	Declared with disclaimer	Programme option
Ecotoxicity	Declared with disclaimer	Programme option
Human toxicity – cancer	Declared with disclaimer	Programme option
Human toxicity – non-cancer	Declared with disclaimer	Programme option
Land use impacts	Declared with disclaimer	Programme option

Characterisation Method Requirements#

The technical methods used to calculate impacts also differ between standards. EN 15804+A2 mandates specific characterisation factors from the European Commission’s Joint Research Centre, ensuring complete consistency. ISO 21930 allows regional programmes to choose methods appropriate to their context – TRACI in North America, LIME in Japan, or CML in some regions. Table 10 compares these methodological requirements.

Aspect	EN 15804+A2	ISO 21930
Method source	EC-JRC only	Regional choice
Climate change	IPCC AR5 GWP 100	IPCC (version varies)
Acidification	Accumulated Exceedance	CML, TRACI, others
Eutrophication	EUTREND model	Various methods
Toxicity	USEtox	USEtox or others
Version control	Centrally managed	Programme managed
Update frequency	With standard revision	Programme discretion

Data Quality and Requirements#

Both standards require high-quality data, but they differ in their specific requirements and flexibility. EN 15804+A2 takes a prescriptive approach, mandating specific data for certain processes and setting strict age and quality requirements. ISO 21930 recognises the challenges of international supply chains and allows more flexibility in data sources.

These differences reflect their contexts: EN 15804 operates within a relatively harmonised European market with good data availability, while ISO 21930 must accommodate vastly different data landscapes globally.

Data Requirements Comparison#

Table 11 compares the key data requirements between standards.

Requirement	EN 15804+A2	ISO 21930
Manufacturing data	Specific data mandatory	Specific data required
Supply chain data	Specific where available	More generic allowed
Data age	<5 years typical	Programme defined
Technological coverage	Current technology	Representative technology
Geographic coverage	Actual locations preferred	Regional acceptable
Proxy data	Limited, justified	More flexible
Documentation	Extensive requirements	Programme varies

Cut-off Criteria Comparison#

Both standards allow excluding minor material and energy flows from the assessment, but EN 15804+A2 is more stringent. These cut-off rules balance completeness with practicality. Table 12 shows the specific limits.

Parameter	EN 15804+A2 Limit	ISO 21930 Limit
Per unit process	1% mass, 1% energy	Not specified
Total excluded	<5% mass and energy	<5% mass and energy
Environmental impact	<5% per category	<5% total
Hazardous materials	Cannot be excluded	Cannot be excluded
SVHC substances	Must be declared	Should be included

Allocation and Recycling Methods#

How the standards handle recycling and multi-output processes represents another fundamental difference. This particularly affects products with recycled content or those that can be recycled at end-of-life – which includes most construction materials.

EN 15804 uses a “cut-off” approach where recycled materials enter the system burden-free (their impacts were allocated to the first use), while ISO 21930 allows programmes to choose different allocation methods. This seemingly technical difference can significantly affect results.

Allocation Approach Comparison#

Table 13 summarises how each standard approaches allocation in various scenarios.

Scenario	EN 15804+A2	ISO 21930
Recycled input	0% burden (cut-off)	Programme choice
Co-product allocation	Physical > Economic	ISO 14044 hierarchy
Waste outputs	No allocation	No allocation
Energy recovery	Current efficiency	Programme defined
Module D calculation	Net output × substitution	Optional method
Avoided burden	Current average tech	Various approaches

Impact on Recycled Content Products#

Recycled Content	EN 15804+A2 Result	ISO 21930 Result
0% recycled	Full virgin impacts	Full virgin impacts
50% recycled	50% virgin impacts	Varies by programme
100% recycled	Only processing impacts	Varies by programme
End-of-life credit	Module D mandatory	If Module D included

Verification and Programme Operations#

The verification landscape represents a practical challenge that significantly affects costs and market access. EN 15804 benefits from the ECO Platform, which enables mutual recognition between major European programmes. Get your EPD verified by IBU in Germany, and it’s automatically recognised by programmes in France, UK, Norway, and dozen other countries. This single verification covers the entire European market.

ISO 21930 lacks this unified approach. Each programme operates independently with its own verification requirements, interpretations, and costs. An EPD verified by UL Environment in the USA isn’t automatically accepted by EcoLeaf in Japan or EPD Australasia. This fragmentation means manufacturers targeting multiple international markets may need three, four, or even five separate verifications of essentially the same EPD.

The verification requirements themselves also differ. While both standards require independent third-party verification, EN 15804 programmes have harmonised their requirements through ECO Platform. ISO 21930 programmes each set their own verifier qualifications, documentation requirements, and review processes. This creates uncertainty and additional cost for international manufacturers.

Market Requirements and Recognition#

Understanding which standard is required in different markets is crucial for EPD strategy. The divide is relatively clear: European markets require EN 15804+A2, while most other regions use ISO 21930. However, the details matter for international manufacturers.

Geographic Requirements#

In Europe, EN 15804+A2 is mandatory across all EU member states, as well as the UK (which retained the standard post-Brexit), Norway, Switzerland, and increasingly Türkiye. The Construction Products Regulation drives this requirement, and no alternative is accepted for regulatory compliance.

North America primarily uses ISO 21930, though interestingly, LEED v4 accepts EN 15804 EPDs. Federal and state procurement policies in the USA typically specify ISO 21930, as do Canadian requirements. Asia-Pacific markets generally prefer ISO 21930, though Japan has its own parallel system and China is developing domestic standards.

Green Building Certification Requirements#

The major green building schemes also show clear preferences. BREEAM, operating primarily in the UK and Europe, requires EN 15804 and doesn’t accept ISO 21930 alternatives. LEED, as a global system, accepts both but shows preference for ISO 21930 on international projects. DGNB in Germany and HQE in France mandate EN 15804, while Green Star in Australia prefers ISO 21930 but accepts both. WELL and the Living Building Challenge, as international standards focused on transparency, accept either.

This geographic split creates a clear decision framework: if you’re focused on European markets, EN 15804+A2 is essential. For global reach, you’ll likely need both standards, though ISO 21930 alone may suffice for non-European international markets.

Decision Framework#

Scenario	Best Choice	Rationale
European sales only	EN 15804+A2	Regulatory requirement
Global exports	Both	Market access
North America focus	ISO 21930	Market preference
Public procurement EU	EN 15804+A2	Tender requirements
International projects	ISO 21930	Broader acceptance
Phased EPD development	ISO 21930 first	Start simple, expand
Complete transparency	EN 15804+A2	All modules mandatory

Multiple Products and Average EPDs#

Both standards allow multiple products to be covered by a single EPD, but their rules differ significantly. This affects manufacturers with product ranges – can you create one EPD for your entire insulation range, or do you need separate EPDs for each thickness and density?

Product Variation Rules#

EN 15804 allows average EPDs when products are “technically equivalent” – they must have the same function and technical performance characteristics. The standard doesn’t specify numerical variation limits, instead requiring that:

• Products use the same manufacturing process
• Technical performance is equivalent for the intended application
• Material composition is similar
• The average represents actual production volumes

ISO 21930 is more prescriptive about variation. Products can be grouped in a single EPD if the variation in environmental impacts doesn’t exceed specific thresholds. While the exact limits can vary by programme operator, typical rules include:

• Maximum ±10% variation in any impact category for averaged products
• Maximum ±25% variation for product ranges (showing min/max values)
• All products must serve the same function
• Manufacturing processes must be similar

Practical Implications for Product Families#

Consider a manufacturer of mineral wool insulation with different densities. Under EN 15804, if all products use the same raw materials and manufacturing process, they might create a single volume-weighted average EPD. The key is demonstrating technical equivalence – all products provide thermal insulation using the same technology.

Under ISO 21930, the same manufacturer would need to check if the environmental impacts vary by more than 10% between densities. If the denser products have 15% higher impacts due to more raw material use, they would need separate EPDs or must present the range showing minimum and maximum values.

This difference significantly affects EPD development strategy. EN 15804‘s approach allows more flexibility for genuinely similar products, while ISO 21930‘s numerical thresholds provide clearer but more restrictive boundaries. Manufacturers with diverse product ranges may find they need fewer EPDs under EN 15804 but must be more careful about demonstrating true technical equivalence.

Practical Examples: Real Product Comparisons#

To understand how these differences affect real products, consider two examples that highlight the key distinctions.

Cross-Laminated Timber Example#

For a CLT panel, the biogenic carbon treatment creates strikingly different EPDs. Under EN 15804+A2, the EPD would show:

• Fossil emissions (A1-A3): 150 kg CO₂e/m³
• Biogenic carbon storage: -800 kg CO₂e/m³ (shown separately)
• End-of-life biogenic release: +800 kg CO₂e/m³ (in Module C)
• Water scarcity: 15 m³ world equivalent

Under ISO 21930, the same product shows:

• Total GWP (A1-A3): 150 kg CO₂e/m³
• A note mentioning “stores 800 kg CO₂e/m³” without standardised presentation
• Module C might not be reported at all
• Water scarcity likely not included

The EN 15804 version provides complete transparency about carbon flows, while the ISO 21930 version may appear to have lower impacts by not showing the eventual release of stored carbon.

Recycled Steel Example#

For structural steel with high recycled content, the allocation rules create different results. EN 15804‘s cut-off approach means recycled steel enters burden-free, with impacts only from remelting and processing. ISO 21930 EPDs might allocate some burden to the recycled content, depending on the programme’s rules.

This can create a 20-30% difference in reported impacts for the same product, affecting competitive positioning in markets where both standards are used.

Conclusion: Strategic Navigation of Dual Standards#

The choice between EN 15804 and ISO 21930 isn’t simply technical – it’s strategic. EN 15804+A2 provides the comprehensive, standardised reporting essential for European markets, with complete life cycle coverage and separated biogenic carbon accounting. ISO 21930 offers the flexibility needed for global trade, allowing partial EPDs and regional adaptation of methods.

For manufacturers serving multiple markets, the question isn’t which standard to choose but how to efficiently comply with both. The key lies in developing robust LCA models that can serve both standards, understanding regional requirements, and strategically timing verification processes. Start with the standard required by your primary market, but design your LCA model with enough flexibility to adapt to the other standard when market expansion justifies the investment.

As environmental transparency becomes mandatory globally, expertise in both standards becomes an increasingly valuable competitive advantage. The standards may converge in the future – ISO 21930 revision discussions are underway – potentially simplifying compliance. Until then, navigating both EN 15804 and ISO 21930 remains essential for construction products competing in international markets.

We hope that this guide has shown you the key differences that matter: mandatory versus optional modules, separated versus combined biogenic carbon, prescribed versus flexible methods. Understanding these differences enables informed decisions about EPD investment and market strategy. Whether entering European markets requiring EN 15804+A2 or pursuing global opportunities through ISO 21930, success depends on choosing the right approach for your specific context.