Product Category Rules: Why Your EPD Is Only as Good as the PCR Behind It

ISO 14025 sets the principles for a credible EPD, but it deliberately leaves the specific measurement rules for individual product types to a separate document: the Product Category Rules, or PCR. This is where the real technical detail lives, and it is also where the quality, defensibility, and comparability of an EPD is actually decided. Two organisations could follow ISO 14025 to the letter and still produce EPDs that cannot be meaningfully compared, simply because they used different PCRs, or different versions of the same one.

What a PCR actually does

A Product Category Rule provides the specific rules and guidance for developing EPDs within a defined product category, so that different practitioners assessing similar products generate consistent, comparable results. A PCR typically sets out the declared or functional unit to use, the system boundary and life cycle stages to include, allocation rules for shared processes, data quality requirements, and the specific environmental performance indicators to declare. Where a PCR covers a broad sector, such as construction products generally, it may be complemented by a complementary PCR, or c-PCR, which adds further rules and guidance for a specific subcategory, such as cement products, without duplicating the content of the main PCR.

PCRs are not written in isolation. In a well governed EPD programme, they are developed through an open, transparent, and participatory process, led by a PCR moderator working with a PCR committee that jointly holds expertise in both the product category and life cycle assessment, and reviewed and approved by a technical committee before publication. This matters because a PCR that has not gone through genuine multi-stakeholder scrutiny is far more likely to contain rules that quietly favour one manufacturer’s process or supply chain over another’s.

Why the PCR determines EPD quality

Because the PCR fixes the declared or functional unit, the system boundary, and the specific indicators to be measured before any data collection begins, it is effectively the yardstick against which every EPD in that category is built. If a PCR’s rules are too loose, allow excessive proxy data, or fail to require disclosure of key methodological choices, every EPD developed against it inherits that weakness, regardless of how carefully the individual life cycle assessment was carried out. Conversely, a well specified PCR, with clear data quality requirements and a genuinely representative declared or functional unit, gives buyers real confidence that EPDs in that category mean what they claim to mean.

This is also why choosing the right PCR, and using the current version of it, is one of the first and most consequential decisions in developing an EPD. A PCR must be valid at the time of verification, and if a c-PCR applies to your product category, it generally needs to be used alongside the applicable main PCR, not as a substitute for it. Where more than one PCR could reasonably apply, the more specific one in terms of product function is typically the better choice, since it produces results that are more directly comparable to genuine competitors.

Validity, updates, and what that means for you

Like the EPDs developed under them, PCRs are valid for a defined period rather than indefinitely, precisely to ensure they are periodically reviewed and updated as methods, data, and industry practice evolve. An expired PCR cannot be used to register a new EPD, or to extend the validity of an existing one, until it has itself been updated or had its validity period renewed. Practically, this means the PCR landscape for your product category is worth checking not just when you first develop an EPD, but throughout its life, since a PCR update partway through your EPD’s validity period does not retroactively invalidate your existing declaration, but it will shape what is required the next time you update or re-verify.

The practical takeaway

Before committing to an EPD, it is worth understanding not just whether a PCR exists for your product category, but how rigorous, current, and genuinely applicable it is to your specific product. A PCR that is a poor technical fit, even if technically available, can produce an EPD that is compliant on paper but weak in the eyes of a sophisticated buyer who knows what to look for.