ISO 20423

ISO/DIS FDIS 20423:2024(en)
Date: 2024-06-10
ISO/TC 234/WG 12
Secretariat: SN
Date: 2025-03-18
Carbon footprint for seafood — Product category rules (CFP-PCR) for
macroalgae
FDIS stage
ISO/FDIS 20423:2025(en)
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Published in Switzerland
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ISO/FDIS 20423:2025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Quantification of the carbon footprint of a product . 1
3.2 Products, product systems and processes . 2
3.3 Data and data quality. 5
3.4 Greenhouse gases . 5
3.5 Waste, storage and transport . 6
4 Calculation and communication requirements . 6
5 Methodological requirements . 7
5.1 General . 7
5.2 Functional unit or declared unit. 7
5.3 Principles of data and methodological reporting . 7
5.4 System boundaries . 8
5.5 Data requirements . 13
5.6 Allocation . 15
5.7 Impact assessment . 15
5.8 Interpretation . 15
5.9 Fossil and biogenic carbon . 16
5.10 Communication of carbon footprints for macroalgae . 16
Annex A (informative) Example of data collection in the calculation of the carbon footprint of
macroalgae products . 17
Annex B (informative) Additional information for farming nutrients accounting through
elemental mass balances of macroalgae . 18
Annex C (informative) Example of mass allocation for kelp co-product processing . 21
Annex D (informative) Example of LCA dried Porphyra yezoensis value-chain modelling . 23
Annex E (informative) Example of LCA ground seaweed value-chain modelling . 26
Bibliography . 28

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ISO/FDIS 20423:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
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This document was prepared by Technical Committee ISO/TC 234, Fisheries and aquaculture.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO/FDIS 20423:2025(en)
Introduction
With the increasingly serious global climate problem, the low-carbon revolution of globalization is rising, and
carbon peaking and carbon neutrality have become important goals of global low-carbon development.
Countries all over the world are actively carrying out double carbon research to achieve the goal of carbon
neutrality as soon as possible.
As an important participant in the ocean carbon cycle, algae can synthesize organic matter through
photosynthesis and release oxygen to achieve carbon sequestration, so it is of great significance to study its
carbon footprint.
This document contains product category rules for the calculation and communication of the carbon footprint
of macroalgae products, providing a convenient and feasible carbon footprint evaluation basis for the
macroalgae farming industry.
This document sets out rules for the calculation and communication of farmed macroalgae products, which
are applicable to the evaluation of the carbon footprint of the entire value chain of farmed macroalgae. The
methodology is based on the requirements of the life cycle assessment and International Standards for the
carbon footprint of products. The overarching aim of the document is to provide a basis for reliable and
accurate information about the climate impact of the product. It is a pre-condition for a market-driven
reduction of climate impact of macroalgae products that dealers and consumers are able to choose the
products with the least climate impact. In addition to this, the document will provide:
— a basis for the development of tools and database for calculating the carbon footprint of macroalgae
products;
— a basis for internal improvement efforts in the macroalgae industry;
— an improved knowledge base concerning the value chains of macroalgae products, their resource
consumption and climate impacts;
— a basis for further understanding the environmental impact of macroalgae products beyond climate
change alone.
This document is intended to function in line with ordinary market mechanisms. Providing credible and
transparent information about the products’ climate impact will pave the way for increased demand and
market value of the most climate-friendly macroalgae products. It will also provide incentives to drive further
improvements and reduce energy consumption and climate impacts from all links in macroalgae value chains.
This document will promotepromotes the transformation of the global fishery industry structure and the
innovative development of low-carbon technology, which can contribute to realizing the construction of low-
carbon fishery and increasing the carbon sink of fishery, thus making due contribution to the global low-
carbon development.
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Carbon footprint for seafood — Product category rules (CFP-PCR) for
macroalgae
1 Scope
This document specifies requirements for calculating the carbon footprint specific to farmed macroalgae
product category rules (CFP–PCR). This methodology builds on the requirements of International Standards
for life cycle assessment (LCA) and products’ carbon footprints.
This document is applicable to the calculation and communication of farmed macroalgae products’ carbon
footprints from seedling production to the consumption of macroalgae products. It is applicable to the carbon
footprints of products from aquaculture value chains.
This document used alone does not apply to specifying a product’s overall environmental or sustainability
characteristics.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 14026:2017, Environmental labels and declarations — Principles, requirements and guidelines for
communication of footprint information
ISO 14040, Environmental management — Life cycle assessment — Principles and framework
ISO 14044, Environmental management — Life cycle assessment — Requirements and guidelines
ISO 14067:2018, Greenhouse gases — Carbon footprint of products — Requirements and guidelines for
quantification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1 Quantification of the carbon footprint of a product
3.1.1
carbon footprint of a product
CFP
sum of greenhouse gas (GHG) (3.4.1) emissions and GHG removals in a product system (3.2.14), expressed as
CO equivalents (3.1.2) and based on a life cycle assessment using the single impact category of climate change
[SOURCE: ISO 14067:2018, 3.1.1.1, modified — Notes 1 and 2 to entry deleted.]

ISO/FDIS 20423:2025(en)
3.1.2
carbon dioxide equivalent
CO equivalent
CO e
unit for comparing the radiative forcing of a greenhouse gas (3.4.1) to that of carbon dioxide
Note 1 to entry: Mass of a GHG is converted into CO2 equivalents by multiplying the mass of the GHG by the corresponding
global warming potential (GWP) or global temperature change potential (GTP) of that gas.
Note 2 to entry: In the case of GTP, CO equivalent is the unit for comparing the change in global mean surface
temperature caused by a GHG to the temperature change caused by CO within a certain time (usually 100 years).
Note 3 to entry: Radiative forcing refers to difference between incoming solar radiation on the Earth and outgoing
thermal radiation from the Earth. A positive radiative forcing tends to warm the surface and a negative radiative forcing
tends to cool the surface.
[SOURCE: ISO 14067:2018, 3.1.2.2, modified — “within a certain time (usually 100 years)” added to Note 2 to
entry. Note 3 to entry added.]
3.1.3
partial carbon footprint of a product
partial CFP
sum of greenhouse gas (GHG) (3.4.1) emissions and GHG removals of one or more selected process(es) in a
product system (3.2.14), expressed as CO equivalents (3.1.2) and based on the selected stages or processes
within the life cycle (3.2.11)
Note 1 to entry: A partial CFP is based on or compiled from data related to (a) specific process(es) or footprint
information modules, which is (are) part of a product system and can form the basis for quantification of a CFP. More
detailed information on information modules is given in ISO 14025:2006, 5.4.
Note 2 to entry: “Footprint information modul
...