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, one of the most common questions manufacturers face is: what is the difference between EN 15804 and ISO 21930? Both provide core rules for construction EPDs, yet the EN 15804 vs ISO 21930 comparison reveals significant differences in market access, verification requirements, and 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.

Non-European markets developed ISO 21930 partly in response to EN 15804’s success. Published by the International Organization for Standardization 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, the +A2 amendment fundamentally changed EN 15804 — redefining how it handles biogenic carbon, which environmental impacts to report, and which life cycle stages are mandatory. ISO 21930 never caught up with these changes, and that gap created 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)

EN 15804 vs ISO 21930: 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 has not 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 in the EN 15804 vs ISO 21930 comparison 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

Scenario Development Requirements#

For the life cycle stages beyond manufacturing, both standards require scenarios — but 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 in the EN 15804 vs ISO 21930 debate 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 is no standardised method for doing so.

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

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

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.

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

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

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.

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

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.

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

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 programme operators. Get your EPD verified by IBU in Germany, and it is automatically recognised by programmes in France, UK, Norway, and a 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 is not 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.

Market Requirements and Recognition#

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 LEED v4 accepts EN 15804 EPDs. Asia-Pacific markets generally prefer ISO 21930, though Japan has its own parallel system and China is developing domestic standards.

The major green building schemes also show clear preferences. BREEAM, operating primarily in the UK and Europe, requires EN 15804 and does not accept ISO 21930 alternatives. LEED, as a global system, accepts both. DGNB in Germany and HQE in France mandate EN 15804, while Green Star in Australia prefers ISO 21930 but accepts both.

EN 15804 vs ISO 21930: Which Standard Should You Use?#

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. EN 15804 allows average EPDs when products are “technically equivalent” — they must have the same function and technical performance characteristics. EN 15804’s approach allows more flexibility for genuinely similar products, while ISO 21930’s numerical thresholds (typically ±10% variation in any impact category for averaged products, ±25% for product ranges) provide clearer but more restrictive boundaries.

Conclusion: Choosing Between EN 15804 vs ISO 21930#

The choice between EN 15804 and ISO 21930 is not simply technical — it is 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 is not 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. Understanding the key differences that matter in the EN 15804 vs ISO 21930 comparison — mandatory versus optional modules, separated versus combined biogenic carbon, prescribed versus flexible methods — enables informed decisions about EPD investment and market strategy.

If you are a UK manufacturer working out which EPD standard applies to your products, get in touch with the Below280 team. We can help you understand your obligations and develop an EPD that works for the markets you sell into.