Part B in PCRs: the product type-specific fine print for your EPD
Ever wondered why a rulebook called "Part A" is never alone? Part B is its sidekick, quietly deciding how your flooring plank or HVAC coil gets measured, compared, and ultimately specced.
Why PCR titles talk about Part B at all
A Product Category Rule comes in two chunks when it follows EN 15804 or ISO 21930. Part A is the core: generic rules for any construction product. Part B layers on product-family tweaks so a gypsum board is not judged by the same yardstick as a window frame (IBU, 2024).
Part A versus Part B in one sentence
Think of Part A as the league rulebook and Part B as the sport-specific add-on. Football and volleyball both share the same anti-doping clause, yet only volleyball cares about net height.
What Part B adds and why bids hinge on it
Part B usually nails down three things: the functional or declared unit, permitted data sets, and any module quirks. For insulation, Part B forces a thermal-resistance unit, which removes wiggle room and makes comparisons fair in LEED v5 submittals (UL Environment, 2025). Miss that rule and your product might look dirtier than it really is.
Spotting the right Part B fast
Open a competitor’s recent EPD. The reference PCR line will list something like “Part B for thermal insulation products”. If your slab insulation belongs to the same spec section, use that PCR, not the generic "other Itms" one. There is two common traps: chasing the freshest date rather than the closest match, and ignoring regional variants that clash with your datasets.
No Part B yet? Two options
- Use the generic fallback Part B offered by some operators, often titled "unclassified construction products." It keeps you compliant but may leave performance nuances out.
- Join an industry working group to draft a new Part B. Plan on six to twelve months of committee calls and public comment rounds. The time sink is real, yet large portfolios sometimes choose it to lock in favorable assumptions (NSF International, 2024).
Renewal check: when Part B shifts beneath you
Part B documents expire every five years on average. Your existing EPD stays valid, but at renewal you must adopt the updated rules. Watch for moves such as new recycling credit caps or extended A4 transport ranges that could nudge impact scores by double-digit percentages. Good LCA partners preview drafts early so you can tweak formulations rather than scramble later.
Wrap-up: read the tiny appendix, win the big project
Clients skim glossy EPD covers, specifiers read Part B citations. Matching the exact Part B their tender expects can be the difference between landing on the shortlist or landing in the recycle bin. Teh fine print pays back.
Frequently Asked Questions
Does Part B replace Part A in a PCR?
No. You always need both. Part A gives the general framework, Part B sharpens it for one product family.
Can I publish an EPD if my product lacks a dedicated Part B?
Yes. Use the program operator’s generic Part B or help draft a new one, but never skip it.
Will switching to a newer Part B change my EPD score?
Quite possibly. Updated data sources or boundary tweaks can swing Global Warming Potential by 5–15 percent, based on IBU renewals in 2024.
How do I find out when a Part B expires?
Check the cover page; operators list an expiration date next to the version number. Calendar reminders beat last-minute scrambles.
About the Author
Walker Ryan is a climate-tech entrepreneur focused on driving industrial decarbonization through better data. As the founder and CEO of Parq, he helps manufacturers generate high-quality, third-party–verified carbon disclosures at scale—accelerating a traditionally slow and expensive process. Before starting Parq, Walker led over $200 million in sustainability-focused investments as VP of Strategy & Growth at ReStream Solutions, following earlier experience in investment banking at Deutsche Bank. He brings a rare mix of capital markets expertise and hands-on sustainability knowledge to tackling the infrastructure of industrial emissions.
