Comparative LCA:
a single expert or a review panel?

A comparative life cycle assessment, or comparative LCA, requires a review panel in one case only: when its conclusion, that a product performs better than or as well as a competing product, is disclosed to the public. In 2017, the Catalan comparison between the current collection of packaging, through street containers, and a mandatory deposit return scheme went before a panel. In 2022, a comparison with the European market was reviewed by a single Norwegian reviewer.

Between these 2 cases, everything depends on the use of the result and the reference chosen. The 3 questions in the tool above settle most situations; borderline cases call for a written decision as early as the scoping of the study.

1What does the standard say about a comparative LCA?

ISO 14044 reserves the panel for comparative assertions disclosed to the public. Its clause 6.1 provides that a panel of interested parties conducts the review when the results are intended to support such an assertion, to limit misunderstandings and effects on external parties, as a 2022 review points out.

The European Commission's ILCD Handbook (International Reference Life Cycle Data System) clarifies the 2 notions, drawing on ISO 14044:

• A comparative assertion concludes, on the basis of the LCA, that one option is superior, inferior or equivalent to another.
• It is disclosed to the public as soon as it goes beyond a limited, well-defined list of parties who took part in the study; a client or a supplier named individually does not count as the public.
• A comparison published with no stated conclusion leaves readers to draw their own; the ILCD Handbook applies the same review requirements to it.

ISO 14071:2024, published in October 2024, sets out how the review is conducted and the competences required of reviewers, and ISO considers it particularly important for these assertions. It creates no new obligation: the use of the result is still what decides.

What consumer law adds

The law imposes no panel. The French Consumer Code already requires comparative advertising to compare, objectively, products that meet the same needs. The EmpCo Directive (empowering consumers for the green transition) expects, in its recital 6, comparisons based on the same function, with a common method and common assumptions and verifiable characteristics. Its date of application is 27 September 2026, but France has not yet transposed it. The rules on comparative advertising are set out in our article on the "less polluting" claim, and the risks involved in the one on enforcement and penalties.

2Who sits on a review panel?

According to the summary of ISO 14044 published by Chalmers University, the panel has at least 3 members. The commissioner appoints a chair, and the panel may bring together technical experts and interested parties affected by the results, such as an association or even a competitor.

The review report on the Catalan deposit return scheme, shown below, gives an example. Commissioned by 11 trade organisations and companies from packaging, beverages and retail, the study compares the current collection system with a mandatory deposit return scheme, a debate revived in Europe by packaging reuse. For its LCA part, the panel has 3 reviewers, including a chair who is a Danish LCA specialist, and sub-panels review the economic and social strands.

• The panel conducted 2 rounds of review, in March and April 2017, on a full report submitted in March.
• The whole panel, sub-panels included, made 350 comments in round 1, technical, general or editorial, then 119 in round 2, mostly editorial.
• On 30 May 2017, the chair signed a review statement finding the method and the conclusions consistent with the ISO 14040 and 14044 standards.

The competences expected of each reviewer and how to choose them are covered in our guide to LCA critical review. The cost of a panel, considerably higher than that of a single expert, is the subject of our article on the price of a critical review.

3What happens when an internal comparison becomes public?

This is the most common case: a study carried out to inform a design decision, such as a first product LCA, ends up in a brochure, on a website or in an advertisement. The obligation follows the use, not the origin of the study: once the comparative conclusion is disclosed to the public, the panel review applies. Passing the study to a named client under a non-disclosure agreement remains a restricted disclosure: no panel is required, but the client must have no way to pass it on as it stands.

The ILCD Handbook therefore recommends deciding on the type of review at the scoping stage, and advises a review conducted in parallel with the study. A poorly framed comparison discovered at the end can delay a comparative assertion by several months, it notes. For a study that is already finished, whose cost has already been incurred, 3 options remain open:

• Submit the existing study to a panel, which reviews a full report, as for the Catalan deposit return scheme: the report must then be completed with the information that ISO 14044 requires of a published comparison.
• Reword the message so that it is no longer comparative, for example by publishing the hotspots of a single product rather than a ranking.
• Keep the study for internal use, and publish nothing that draws a comparative conclusion from it, even in the form of a chart.

If the comparison is published, ISO 14044 prohibits weighting the indicators, as the 2022 report also points out. An internal study built on a single score therefore has to be reworked indicator by indicator, like an electric car LCA that does not reach the same conclusion on every impact.

4Market average or previous version: is a single expert enough?

The wording of the standard refers to a competing product that performs the same function. 2 references fall outside the letter of the text, and reviewers treat them differently.

Comparison with a market average

In 2022, the review of the XyloBond study, which compares lignin from Borregaard with competing products, was entrusted to a single external reviewer. The reviewer accepted this single-reviewer arrangement on 2 conditions: the study compares itself with the generic European market, and it explicitly rules out any conclusion about a specific manufacturer's product. The reviewer also requires these limitations to accompany the results wherever they are disclosed.

Comparison with a previous version of the same product

Comparing the new version of a product with the old one targets no competitor, and an independent expert is often considered sufficient. The ILCD Handbook is stricter: it applies the requirements for published comparisons to any disclosed comparison of products, except hotspot analyses of a single product. A claim such as "30% less than our previous model" also falls under the rules on substantiating a claim and on banned claims.

These 2 cases are grey areas: the standard does not require a panel, and the choice of a single expert must be justified in writing. The matrix below summarises the 4 combinations of use and reference.

5How do you write the right level of review into the contract?

The level of review is set before the calculation and put in writing, alongside the internal checks on the model and, for an advertising message, an audit of the claims. 4 provisions prevent most misunderstandings between the commissioner, the author of the study and the reviewers:

• The contract states the intended use of the result (internal decision, named client, advertising or public report) and the audience that will read it.
• It names the reference for the comparison: an identifiable competing product, a published and dated average, or a previous version.
• It sets the type of review, single expert or panel, with the written reason for that choice when the reference is a grey area.
• It specifies what the review statement will say, the standard followed and the use for which the study is found fit, to be reused as it stands in communications.

A review by a single expert is not equivalent to a panel review: if the use changes, a panel takes the study up again. For an FDES (the French format of environmental product declaration for construction products) or an EPD, the process is different again: verification by an approved verifier.

For us at Projet Celsius, the question to ask on the first day is simple: will a competitor read this conclusion? If so, a panel; if the answer is uncertain, a scope that provides for a panel from the outset. We review comparative LCAs carried out by others, as a single expert or as part of a panel, and never a study we carried out ourselves.

6Key takeaways

• A comparative LCA requires a panel of at least 3 members when its conclusion targets a competitor and is disclosed to the public.
• An internal comparison becomes public once it leaves the circle of named parties: the review follows the use, not the study.
• A market average or a previous version are grey areas: choosing a single expert there must be justified in writing.
• The law does not impose a panel, but it does require an objective comparison between products with the same function.
• The type of review is written into the contract, together with the intended use and the reference for the comparison.

To choose the reviewers and understand what a review report contains, see our guide to LCA critical review.

Further resources

Frequently asked questions

1Does a comparative LCA always need a panel review?

No. ISO 14044 requires a panel when the study supports a comparative assertion disclosed to the public, that is, a claim that a product performs better than or as well as a competing product. A comparison for internal use may be reviewed by an independent expert, or not reviewed at all.

2How many members does a review panel have?

At least 3, including a chair appointed by the commissioner. The panel may include technical experts and interested parties affected by the results. For the packaging deposit return scheme in Catalonia, in 2017, 3 reviewers reviewed the LCA part, within a panel that made 469 comments over 2 rounds.

3Can you publish a comparison reviewed by a single expert?

Only if it targets no identifiable competing product, for example a comparison with a market average that rules out any conclusion about a manufacturer. The choice must be justified in the report, and the limitations of the comparison must accompany the results wherever they are disclosed.

4Does a comparison with the previous version of your own product need a panel?

The standard does not require one, since no competitor is targeted, and an independent expert is often considered sufficient. The European Commission's ILCD Handbook nevertheless recommends the same requirements for any published comparison of products. The decision is written down at the scoping stage.

5Can a competitor sit on the review panel?

Yes. According to the summary of ISO 14044 published by Chalmers University, the panel may bring together technical experts and interested parties affected by the results, including competitors or associations. Their presence makes the comparison stronger against challenges, provided the chair remains independent of the study.

6Does the law require a critical review for a comparative claim?

No. The French Consumer Code requires an objective comparison of products that meet the same needs, and the EmpCo Directive, not yet transposed in France, expects a common method. Critical review by a panel comes from ISO 14044, and it is the strongest evidence when an LCA supports a public comparison.

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