The GHG Protocol Product Standard

Most organisations meet the GHG Protocol through the Corporate Standard and its Scope 1, 2 and 3 structure. The Product Standard is a different document answering a different question, and conflating them produces figures that do not mean what people think.

The distinction is simple to state and easy to lose: corporate accounting asks what an organisation emitted in a year; product accounting asks what one unit of a product causes across its life.

What the Product Standard requires

The last row is where the value is. Corporate figures are designed to be compared with the same organisation’s previous year; product figures are designed to be compared with another product, which is a considerably harder requirement.

Why you cannot divide one by the other

A frequent shortcut is to take total corporate emissions and divide by units shipped. It produces a number and the number is not a product footprint.

Corporate emissions cover a reporting year and an organisational boundary. They exclude most upstream emissions unless Scope 3 is complete, exclude the use phase almost entirely, and include overheads unrelated to any specific product. Dividing mixes an annual organisational figure into a per-unit life cycle claim.

How does it relate to ISO 14067?

ISO 14067 specifies the quantification and reporting of a product carbon footprint and is built on the ISO 14040 and 14044 life cycle assessment framework. It covers substantially the same ground as the GHG Protocol Product Standard.

The two were developed in parallel and are broadly aligned. Which to cite is usually determined by your audience: ISO references carry more weight with international suppliers and technical reviewers, while GHG Protocol references are more familiar to sustainability teams already using the Corporate Standard.

What the standard asks you to decide

1. The functional unit, expressing what the product does rather than what it is.
2. The boundary, including whether the use phase and end of life are counted.
3. The allocation method where processes yield co-products.
4. Data quality requirements, and which stages need primary data.
5. How land use change and biogenic carbon are treated, if relevant.

The fifth is the most technically contested and matters intensely for agricultural and forestry-derived products. Biogenic carbon accounting choices can move a footprint from positive to negative, which is not a rounding difference.

Where product and corporate data overlap

Substantially, and they are collected differently. Scope 3 category 1 covers purchased goods and services, which is the same supplier emissions data a product footprint needs, gathered at organisational rather than product granularity.

An organisation collecting supplier data at product level can aggregate upward to satisfy Scope 3; one collecting at spend level cannot disaggregate downward to a product. Collection granularity is therefore a decision that determines which reports are possible later.

What does a conforming study actually involve?

More process than most teams expect, and less mathematics. The quantification itself is arithmetic once the inventory exists; the work is in defining the study, obtaining supplier figures and documenting every choice so a reviewer can follow it.

The standard also requires an assurance step for public claims, and a description of uncertainty. A study reporting a single figure with no uncertainty discussion has skipped a requirement, and that omission is usually visible to a reviewer immediately.

For most manufacturers the first product study takes a quarter or more, and the second takes a fraction of that. Almost all of the first study’s cost is establishing supplier data routes that the second reuses, which is the same pattern that governs passport programmes generally.

How often should a footprint be recalculated?

When something material changes: a supplier, a production route, a formulation, or the electricity contract at a major site. Recalculating annually regardless of change consumes effort without producing new information.

The practical rule most organisations settle on is a full recalculation every few years with an interim review whenever a bill of materials or a principal supplier changes. Recording which version of the figure a given production run carries is what makes that workable, and it is another argument for holding the value against the product record rather than in a report.

What it means for the passport

A passport carbon field is a product footprint, so it is the Product Standard or ISO 14067 that governs it, not the Corporate Standard. Populating it from a corporate figure divided by volume is the specific error this distinction exists to prevent.

The field should carry the standard used alongside the number, because a reader cannot otherwise tell which question was answered. That is the same disclosure principle behind boundary and allocation reporting.