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.

If you make construction products and someone has asked you for an EPD, you are likely facing the same question: EN 15804 or ISO 21930? Both are standards for Environmental Product Declarations (EPDs) for construction products, both are widely used, and both produce a document called an EPD. But they are not interchangeable. The EN 15804 vs ISO 21930 comparison matters because choosing the wrong standard for your market can mean your EPD is rejected, a tender is lost, or you end up paying for a second verification. This guide explains what sets them apart and which one applies to you.

Why Are There Two Standards for Construction EPDs?#

EN 15804 came first, published in 2012 to harmonise construction product environmental declarations across European member states. The Construction Products Regulation needed a consistent method for environmental assessment, and EN 15804 provided it. Its success prompted international interest in a global equivalent.

Non-European markets developed ISO 21930 in response, published by the International Organization for Standardization in 2017. At the time, ISO 21930 was deliberately aligned with EN 15804 as it stood in 2013. The two standards used the same modular structure, similar impact categories, and comparable LCA approaches.

However, the divergence came in 2019 when the +A2 amendment significantly changed EN 15804, redefining how biogenic carbon is handled, which environmental impacts must be reported, and which life cycle stages are mandatory. ISO 21930 was never updated to match, and that gap is what creates confusion 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. When ISO 21930 was published in 2017, it aligned closely with EN 15804+A1. The two were broadly equivalent. The divergence came two years later, driven by European regulatory changes that ISO 21930 has not yet followed.

Table 2 shows the key milestones in both standards’ development. Note how ISO 21930 aligned with EN 15804+A1 but has not updated to match the significant changes introduced 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, both of which reference EN 15804 specifically. International markets rely on ISO standards for trade facilitation and compatibility with global green building schemes like LEED.

Core Methodological Differences#

The most fundamental difference between EN 15804 and ISO 21930 is what each standard requires you to report. EN 15804+A2 requires complete life cycle coverage, from raw material extraction through to end-of-life and beyond. In contrast, ISO 21930 takes a more flexible approach, mandating only the production stage while leaving everything else optional.

In practice, this means an EN 15804 EPD tells the full environmental story of a product, including what happens during installation, use, and disposal. An ISO 21930 EPD can focus solely on cradle-to-gate impacts, which is simpler to produce but gives specifiers and procurement teams less to work with.

Life Cycle Module Requirements#

Table 3 shows which life cycle modules each standard requires. EN 15804+A2 mandates all modules; 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 life cycle stages beyond manufacturing, both standards require scenarios to be developed. EN 15804 makes these mandatory; ISO 21930 leaves them optional. Table 4 summarises what scenarios each standard requires.

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#

For manufacturers of timber, bamboo, or other bio-based construction products, the treatment of biogenic carbon is the most commercially significant difference between the two standards.

EN 15804+A2 introduced separate reporting of fossil and biogenic carbon. Carbon stored in timber appears as a negative emission when the tree grows and a positive emission when the wood eventually decomposes or burns. For sustainably managed forests, the net effect over the full life cycle is zero, but the separation gives architects and specifiers clear visibility of the carbon storage benefit during the building’s use phase.

ISO 21930 takes the traditional approach of combining all carbon into a single Global Warming Potential value. Programmes may allow separate reporting of biogenic carbon as additional information, but there is no standardised method for doing so. Table 5 shows how each standard treats the different carbon types.

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

Biogenic Carbon in Practice: The CLT Example#

To make this concrete, consider cross-laminated timber (CLT). Under EN 15804+A2, the EPD would show a large negative biogenic carbon value at production stage (the carbon stored in the wood) and a corresponding positive value at end-of-life. Under ISO 21930, both would be absorbed into a single total figure, making the carbon storage benefit much harder to communicate to specifiers. Table 6 shows this difference in practice.

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

Notably, both standards prohibit carbon offsets and temporary storage credits. Table 7 summarises the carbon accounting rules that apply to both.

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 in which environmental impacts must be assessed and reported. EN 15804+A2 expanded its requirements considerably, adding a mandatory water scarcity indicator, splitting eutrophication into three separate categories, and requiring additional toxicity and particulate matter indicators.

ISO 21930 maintains a more traditional set of impact categories and allows regional programmes to choose which specific methods to apply. This gives flexibility but reduces comparability between EPDs produced under different programmes. Table 8 shows exactly which categories each standard requires.

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 requires six additional indicators to be declared, though with a disclaimer noting that the scientific methods behind them are still developing. ISO 21930 leaves these to programme discretion. Table 9 shows their status under each standard.

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

Impact Assessment Methods#

The standards also differ in which impact assessment methods are permitted. EN 15804+A2 prescribes EC-JRC methods only, ensuring consistency across all European EPDs. ISO 21930 allows regional programmes to choose from multiple methods, which can make direct comparison between EPDs from different programmes unreliable. Table 10 summarises the differences.

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 how prescriptive they are. EN 15804+A2 mandates specific data for certain processes and sets strict age and quality requirements. ISO 21930 acknowledges 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

Cut-off Criteria#

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 is another area of significant difference. It particularly affects products with recycled content or those you can recycle at end-of-life, which covers most construction materials.

EN 15804 uses a cut-off approach: recycled materials enter the system burden-free, because it allocates their production impacts to the first use. ISO 21930 allows programmes to choose different allocation methods. This technical difference can produce meaningfully different results for the same product.

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#

Verification is where the practical cost difference between the two standards becomes most visible, especially for manufacturers targeting more than one market.

EN 15804 benefits from the ECO Platform, which enables mutual recognition between major European programme operators. Get your EPD verified with IBU in Germany, and programmes in France, the UK, Norway, and a dozen other countries automatically recognise it. One verification covers the entire European market.

ISO 21930 has no equivalent system. Each programme operates independently with its own verification requirements, interpretations, and costs. EcoLeaf in Japan or EPD Australasia won’t automatically accept an EPD that UL Environment verified in the USA. 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 regulators accept no alternative for 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?#

For most UK manufacturers, the answer is EN 15804+A2. If your products go into European construction projects, are specified under BREEAM, or need to meet UK or EU public procurement requirements, EN 15804 is not optional. Table 15 covers the main scenarios.

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 let a single EPD cover multiple products, but their rules differ. EN 15804 allows average EPDs when products are technically equivalent, meaning they share the same function and technical performance characteristics. ISO 21930 uses numerical thresholds, typically allowing averaged products where no single impact category varies by more than 10%, or up to 25% for product ranges. EN 15804’s approach allows more flexibility for genuinely similar products; ISO 21930’s thresholds are clearer but more restrictive.

Conclusion: Choosing Between EN 15804 vs ISO 21930#

The choice between EN 15804 and ISO 21930 is not a technical preference, it is a market decision. EN 15804+A2 is the standard for Europe, with mandatory life cycle coverage, separated biogenic carbon reporting, and a unified verification system that covers most of your potential customers in one go. ISO 21930 is the standard for global trade, offering more flexibility but requiring programme-by-programme verification if you are targeting multiple international markets.

If you sell into both, the most efficient approach is to build an LCA model flexible enough to serve both standards, start with the one required by your primary market, and expand when the business case justifies it. The standards may converge in the future, as committees are currently discussing ISO 21930 revisions, but for now, understanding which one your customers actually need saves time, money, and the frustration of an EPD that a client rejects at tender stage.

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.

FAQs#