10. What are Product Category Rules (PCRs)?

Product Category Rules are the specific methodological requirements that make EPDs within a product category comparable rather than just a collection of incomparable environmental studies. Without PCRs, every manufacturer would define their own system boundaries, choose their own impact categories, and make their own allocation decisions. The resulting EPDs would all be technically valid but impossible to compare meaningfully.

PCRs solve this problem by establishing detailed rules for conducting Life Cycle Assessment and creating EPDs within a defined product category. The PCR for insulation specifies exactly how to assess insulation products. The PCR for concrete defines precisely what goes into a concrete EPD. These detailed specifications eliminate the flexibility that makes general LCA studies incomparable.

Understanding what PCRs contain, how they’re developed, and why they matter helps you navigate EPD creation and interpret EPDs correctly. PCRs are the mechanism that transforms EPDs from individual declarations into a system enabling fair comparison.

What PCRs Actually Contain#

A PCR is a technical document, typically 30-60 pages, specifying methodology for a product category. It builds on ISO 14025 and ISO 14040/44 but adds product-specific detail.

Product category definition establishes exactly what products the PCR covers. A window PCR might cover all window systems or might separate aluminium windows from timber windows. The definition determines which products can use the PCR and which need different rules.

Category definitions balance specificity against practicality. Too broad and products with fundamentally different environmental profiles get lumped together. Too narrow and you need dozens of PCRs for minor variations, creating fragmentation.

Functional unit or declared unit specifies the reference quantity for reporting results. Most construction products use declared units (1 kg, 1 m², 1 m, 1 item) rather than functional units. The PCR states which unit applies and how to define it precisely.

For insulation, the declared unit might be “1 m² of insulation at declared thickness and density.” For concrete, it might be “1 m³ of ready-mix concrete at declared strength class.” Precision matters because results must be reportable consistently.

System boundaries define which life cycle stages must be included. Following EN 15804, construction product PCRs now require at minimum Modules A1-A3 (production), C1-C4 (end of life), and D (beyond system boundary). Some PCRs mandate additional modules. Others leave certain modules optional.

The PCR specifies exactly what goes into each module. For Module A1, what’s included as raw material supply? For Module A3, what’s considered part of manufacturing versus subsequent installation? These boundaries prevent manufacturers from drawing lines favourably.

Data quality requirements establish minimum standards for data collection. The PCR might require:

• Primary manufacturing data covering at least one year
• Specific percentages of primary versus secondary data by environmental significance
• Database versions and data currency (data less than 10 years old)
• Geographic relevance of data
• Cut-off criteria for excluding processes

Stricter data quality requirements mean more representative EPDs but higher data collection burdens. PCRs balance these considerations based on product category characteristics and data availability.

Impact categories and assessment methods list which environmental impacts must be calculated and which characterisation factors to use. Construction product PCRs following EN 15804+A2 mandate specific impact categories and European Commission characterisation methods. Other PCRs might use TRACI methods or other approaches.

The PCR doesn’t just say “calculate climate change.” It specifies which characterisation factors from which source to apply to which emission types. This eliminates methodology variation between EPDs.

Allocation rules define how to divide environmental impacts between co-products or how to handle recycling. These rules are critical because allocation choices dramatically affect results.

For a manufacturing process producing both the primary product and valuable by-products, does the by-product get credited with avoiding virgin production (substitution approach) or do impacts get divided based on mass, economic value, or other allocation keys? The PCR specifies the approach.

For recycled content, does the product get credited for using recycled materials? How much credit? What’s the baseline for comparison? The PCR determines these rules.

Scenarios for life cycle stages beyond the manufacturer’s control get documented. Transport to site, installation, use stage activities, and end-of-life treatment all depend on conditions the manufacturer can’t know. The PCR provides default scenarios or rules for developing scenarios.

A PCR might state: “For Module A4, assume average transport distance 500 km by truck with 20-tonne capacity at 80% load factor, unless more specific information is available.” This gives a baseline while allowing refinement based on better information.

Additional technical information requirements ensure EPDs support building-level assessment. The PCR specifies what product properties, performance data, and technical characteristics must be reported beyond environmental impacts.

Why PCRs Exist: The Comparability Problem#

Before PCRs, Life Cycle Assessment studies of similar products reached contradictory conclusions because methodological choices varied. One study might exclude packaging while another included it. One might use European electricity data while another used global averages. One might allocate co-product impacts by mass while another used economic allocation.

Each choice was defensible within general LCA methodology, but the different choices made comparison meaningless. A product appearing environmentally better might just have been assessed with more favourable assumptions.

PCRs remove this flexibility within product categories. Every EPD for flat glass follows the same PCR. System boundaries, allocation rules, and impact assessment methods are identical. Differences in results then reflect actual product differences, not methodology choices.

This standardisation is what enables comparing EPDs. You can compare two concrete EPDs knowing they used the same rules. You cannot meaningfully compare concrete EPDs from different PCRs because methodology might differ despite both being valid under ISO 14025.

PCR Development Process#

ISO 14025 requires PCRs to be developed through open, consultative processes involving interested parties. The process typically takes 6-18 months.

Initiating PCR development usually comes from industry associations, major manufacturers, or programme operators identifying need. Someone must commit resources to driving the process.

Conducting preparatory LCAs is mandatory. Before writing a PCR, someone must conduct detailed Life Cycle Assessments of products in the category. These studies identify significant environmental aspects, reveal where methodological choices matter most, and inform PCR requirements.

This preparatory work prevents PCRs from being written based on assumptions about what matters. Actual LCA data shows where impacts occur and which methodology choices significantly affect results.

Stakeholder identification and engagement involves finding interested parties including manufacturers, customers, environmental groups, academics, and technical experts. The programme operator must provide transparent procedures for participation.

Stakeholder engagement happens through meetings, comment periods on draft PCRs, and consultation rounds. Different stakeholders have different priorities. Manufacturers want feasible data requirements. Environmental groups want comprehensive coverage. Customers want comparability. Technical experts want methodological rigour.

Balancing these interests creates PCRs that are rigorous but practical, comprehensive but feasible.

Drafting the PCR requires LCA expertise, product category knowledge, and understanding of ISO requirements. The draft must address all required elements while remaining clear and implementable.

Good PCRs are specific enough to ensure consistency but not so prescriptive that they’re impossible to follow. They provide clear rules without unnecessary complexity.

PCR review is mandatory. An independent panel of at least three members with combined expertise in the product category, LCA methodology, and environmental aspects must review the PCR. This review verifies:

• Conformance with ISO 14040/44 LCA requirements
• Conformance with the programme operator’s general instructions
• Appropriateness of the prescribed methodology for the product category
• Adequacy of requirements to capture significant environmental aspects

The review panel can require revisions before approving the PCR. Their oversight ensures PCR quality.

Publication and registration makes the PCR available for EPD development. Most programme operators maintain searchable PCR registries where you can find relevant PCRs for your products.

PCR Validity and Updates#

PCRs don’t last forever. They typically remain valid for five years but may require updates sooner if:

• Underlying standards change (e.g., when EN 15804+A2 superseded earlier versions)
• Manufacturing processes change substantially
• New environmental issues emerge requiring additional indicators
• Technology changes enough that scenarios become outdated
• Stakeholder consensus evolves on appropriate methodology

PCR updates follow similar processes to initial development: stakeholder consultation, technical revision, and review. Updates aim to improve PCRs while maintaining reasonable continuity so existing EPDs don’t become immediately invalid.

When PCRs update, existing EPDs created under the old version typically remain valid until their expiry dates. New EPDs must follow the updated PCR. This creates transition periods where EPDs following different PCR versions coexist.

PCR Harmonisation: The Unrealised Dream#

ISO 14025 encourages programme operators to harmonise PCRs to enable cross-programme comparison. In theory, the PCR for concrete should be the same regardless of which programme operator publishes it.

In practice, PCR harmonisation is limited. The same product category often has multiple incompatible PCRs across different programmes:

• EPD International’s PCR for a product
• IBU’s PCR for the same product
• Regional operators’ PCRs with different rules

These PCRs might differ in system boundaries, required modules, allocation rules, or scenarios. EPDs following different PCRs aren’t directly comparable even though both comply with ISO 14025.

Harmonisation efforts exist. The European Construction Products Regulation pushes toward consistent requirements. ECO Platform coordinates between European construction product EPD programmes. Some programme operators have mutual recognition agreements.

But complete harmonisation remains elusive. Regional differences in manufacturing, energy systems, and markets create legitimate reasons for varying PCR requirements. Regulatory timelines and stakeholder priorities differ between regions. Technical debates about allocation or system boundaries don’t have universal answers.

For users, this means checking that EPDs follow compatible PCRs before comparing. For manufacturers selling globally, this might mean creating EPDs under multiple PCRs to satisfy different markets.

Finding the Right PCR#

Before creating an EPD, you need to identify which PCR applies to your product.

Search programme operator registries for PCRs matching your product type. Most operators provide searchable databases with keywords, product categories, and PCR titles.

Check PCR scope carefully. A PCR title might seem applicable but the scope definition might exclude your product. Read the product category definition section to verify your product fits.

Verify PCR currency. Check the publication date and validity period. Using expired PCRs isn’t permitted. If the most recent PCR is about to expire, contact the programme operator about timing and potential updates.

Assess feasibility. Read the PCR requirements thoroughly. Can you obtain the required data? Do the system boundaries match what you can model? Are allocation rules applicable to your situation?

Consider alternatives if no direct match exists. Some programmes have generic PCRs for products without specific rules. These are less ideal but may be workable. You might also consider whether a related product PCR could apply with justification.

Engage the programme operator if uncertainty exists. They can clarify whether your product fits within existing PCRs or whether new PCR development is needed.

When Suitable PCRs Don’t Exist#

If your product category lacks a PCR, you face several options:

Use a generic PCR if the programme provides one. Generic PCRs offer flexibility but less comparability. They’re better than nothing but don’t enable the detailed comparison that product-specific PCRs support.

Initiate PCR development if you’re willing to invest resources. Developing a PCR requires funding preparatory LCAs, coordinating stakeholder engagement, and supporting the development process. Costs typically range £20,000-50,000 or more.

First-mover advantage exists. The company initiating PCR development influences the rules (subject to stakeholder input and review). If you have environmental advantages, shaping PCR methodology to reflect them benefits you. But you also bear the costs and time burden.

Wait for others to develop the PCR. If your product category is emerging or small, someone might develop a PCR eventually. Waiting saves you development costs but delays your ability to create EPDs.

Consider whether EPDs are premature. For truly novel products without comparable alternatives, EPDs might not be necessary yet. Focus on performance improvement and data collection infrastructure. Pursue EPDs when the product category matures.

PCRs and Building-Level Assessment#

PCRs design EPD data to support building-level environmental assessment under standards like EN 15978. The modular structure, scenario requirements, and technical information serve this purpose.

When architects use EPDs in building assessments, they aggregate Module A impacts from all products for production stage totals. They use Module B data with building operational analysis. Module C integrates into building end-of-life assessment. Module D benefits aggregate at building level.

PCR requirements ensure this aggregation works. Consistent functional units, compatible system boundaries, and appropriate scenarios let EPD data feed building calculations accurately.

PCRs also specify technical information that building assessors need beyond environmental data: thermal performance, durability, maintenance requirements, and other characteristics affecting building-level performance.

The Limits of PCRs#

PCRs enable comparison within product categories following the same PCR. They don’t solve all comparability challenges.

Cross-category comparison remains problematic. PCRs for insulation versus PCRs for windows use different functional units, different scenarios, and may emphasise different life cycle stages. Comparing insulation to windows using EPD data alone misses functional differences.

Comparing across categories requires building context. You don’t compare insulation to windows. You compare building thermal performance with different combinations of insulation and windows, considering how products interact with building energy systems.

PCR scope boundaries can be arbitrary. Where does “window” end and “wall system” begin? Products that integrate multiple functions might fit awkwardly into PCR categories designed for discrete components.

Technology evolution can outpace PCRs. New materials, processes, or product designs might not fit established PCR assumptions. PCRs need updating but updates take time.

Regional variations aren’t always captured. A PCR might assume European manufacturing conditions. Products made in Asia with different energy systems, databases, and practices might not fit well.

Despite limitations, PCRs remain the best mechanism available for enabling comparable environmental declarations. They’re not perfect but they’re vastly better than unstructured LCA studies.

PCRs in Practice#

When you work with EPDs, PCR understanding matters:

As an EPD creator, the PCR is your rulebook. Everything in your EPD must conform to PCR requirements. Deviations mean verification problems. Read the PCR thoroughly before starting data collection.

As an EPD user, the PCR tells you what the EPD contains and doesn’t contain. Understanding PCR scope helps you interpret results correctly and know when comparison is valid.

As a specifier or buyer, knowing that EPDs follow PCRs explains why you can compare some EPDs directly but others require more careful analysis. Checking PCR compatibility is part of proper EPD comparison.

The PCR is referenced in every EPD document. The EPD states which PCR it follows, usually in the first few pages. If you need to understand an EPD deeply, download and read the PCR it references.

The Future of PCRs#

PCR development continues as new product categories need EPDs and existing PCRs get updated. Trends include:

Greater harmonisation pressure from regulations requiring EPDs. When regulations mandate declarations, having dozens of incompatible PCRs for the same products becomes problematic.

Digital PCRs and machine-readable rules to enable automated compliance checking and digital EPD formats. Current PCRs are text documents. Future PCRs might include structured data that software can interpret.

Broader scope integration as products become more complex and integrated. PCRs might evolve to cover systems rather than just individual components.

More sophisticated methodologies as LCA science advances. New impact categories, better allocation approaches, and improved scenario modelling will feed into PCR updates.

The fundamental purpose remains: enabling comparable, credible environmental declarations by removing methodology flexibility within product categories. PCRs will continue serving this purpose even as specific approaches evolve.

Key Takeaways#

Product Category Rules are the mechanism that makes EPDs comparable. They remove the flexibility that makes general LCA studies incomparable, imposing standardised rules within product categories.

Good PCRs balance rigour with practicality, comprehensiveness with feasibility. They result from stakeholder consultation and technical expertise, reviewed independently before publication.

Finding and following the right PCR is essential for creating EPDs. Understanding PCR scope and requirements is essential for using and comparing EPDs correctly.

PCR harmonisation remains incomplete, creating comparison challenges when EPDs follow different PCRs. But within programmes and PCRs, the standardisation works, enabling the fair comparison that EPDs promise.