What is EN 16485? Understanding EPDs for Wood and Wood-Based Products

Wood products present unique challenges for environmental assessment. How do you account for carbon stored in timber? When can you claim carbon neutrality? How do you allocate impacts between lumber and sawdust? EN 16485 provides the answers, establishing specific rules for wood product EPDs that build on EN 15804.

If you’re working with timber, engineered wood, or any wood-based construction product, understanding EN 16485 is essential for creating credible EPDs that properly reflect wood’s environmental characteristics.

EN 16485: The Wood-Specific PCR#

EN 16485, published in 2014, provides complementary Product Category Rules specifically for wood and wood-based products used in construction. It doesn’t replace EN 15804 but adds sector-specific requirements that address wood’s unique properties.

Think of it this way: EN 15804 provides the foundation for all construction EPDs. EN 16485 builds on that foundation with specific rules for timber products, from round logs to glulam beams, from particle board to cross-laminated timber.

The standard recognises that wood differs fundamentally from other construction materials:

1. Trees absorb CO₂ as they grow, storing carbon in wood fibres
2. Wood is both a material and an energy source
3. Forestry produces multiple co-products from a single tree
4. Wood products can be recycled, reused, or burned for energy
5. The sustainability of forest management affects carbon neutrality assumptions

These characteristics require specific methodological approaches that generic construction PCRs cannot adequately address.

The Biogenic Carbon Challenge#

The most contentious aspect of wood LCAs involves biogenic carbon – the carbon dioxide trees absorb from the atmosphere and store in their wood. This stored carbon creates complexity in environmental assessment.

The System Boundary with Nature#

EN 16485 makes a crucial distinction about where the product system begins. The standard states that forests are natural systems with multiple functions, timber production being just one. Therefore:

1. Natural growth and decay processes aren’t attributed to timber production
2. Forest carbon pool changes must be assessed at landscape level, not individual stands
3. Only technical forestry operations (planting, thinning, harvesting) fall within the system boundary

This approach prevents double-counting and ensures consistency across wood product EPDs.

Carbon Neutrality Assumptions#

EN 16485 allows carbon neutrality assumptions (the “-1/+1 approach”) only under specific conditions:

1. Wood comes from countries accounting for Article 3.4 of the Kyoto Protocol, OR
2. Wood originates from certified sustainable forest management schemes

Currently, all major European timber-producing countries report increasing forest carbon pools under Kyoto Protocol reporting, supporting carbon neutrality assumptions for European timber.

For wood of unknown origin or from unsustainably managed forests, carbon neutrality cannot be assumed. The standard requires accounting for forest degradation impacts in these cases.

Tracking Carbon Through the Life Cycle#

The standard provides precise characterisation factors for biogenic carbon:

1. Wood entering the system: -1.83 kg CO₂/kg oven-dry wood
2. Wood leaving the system: +1.83 kg CO₂/kg oven-dry wood

This “-1/+1” approach means carbon storage provides a benefit when wood enters the product system but creates an emission when it eventually releases that carbon (through decay or combustion).

For scenarios where carbon neutrality cannot be assumed, the standard provides different factors that account for forest carbon pool degradation.

Material Inherent Properties#

EN 16485 requires tracking two key material properties throughout the life cycle:

Biogenic Carbon Content#

Every wood product must declare its biogenic carbon content based on oven-dry mass. The standard provides the calculation:

• 1 kg of biogenic carbon = 44/12 kg CO₂ (3.67 kg CO₂)
• Wood typically contains about 50% carbon by oven-dry mass

Energy Content#

Wood’s calorific value must be tracked as both:

• Lower heating value (LHV) for energy calculations
• Material inherent property for resource accounting

This dual tracking ensures proper accounting when wood serves as fuel in end-of-life scenarios.

Allocation Rules for the Wood Chain#

Forestry and wood processing generate multiple products from single inputs. A tree yields sawlogs, pulpwood, and residues. A sawmill produces lumber, chips, and sawdust. EN 16485 provides specific allocation rules for these multi-output processes.

Forest Operations#

The standard requires allocation between different wood assortments (sawlogs, pulpwood, energy wood) based on economic value. This reflects market drivers for forest management decisions.

Sawmill Allocation#

For sawmills producing both lumber and co-products:

1. Primary allocation should be avoided through subdivision where possible
2. If unavoidable, economic allocation is typically applied
3. The allocation must reflect actual market values, not theoretical ones

Cascading Use#

When wood products are recycled into new products (cascading), the standard distinguishes between:

1. Closed-loop recycling (same product type)
2. Open-loop recycling (different product type)
3. Energy recovery

Each scenario has specific calculation rules for Module D benefits.

System Boundaries and Modules#

EN 16485 follows EN 15804’s modular structure but adds wood-specific requirements:

Product Stage (A1-A3)#

Must include:

1. All forestry operations (establishment, tending, harvesting)
2. Transport from forest to processing
3. Manufacturing processes
4. Accounting for biogenic carbon uptake

The standard clarifies that impacts from extracting logging residues for bioenergy aren’t attributed to timber products, as these activities aren’t causally linked to timber production.

Use Stage (B1-B7)#

For most wood products, the use stage involves:

1. Potential emissions from preservatives or coatings
2. Maintenance and replacement scenarios
3. No biogenic carbon flux (carbon remains stored)

End of Life (C1-C4)#

Critical considerations include:

1. Release of stored biogenic carbon
2. Allocation between recycling, energy recovery, and disposal
3. Degradation rates in landfills (wood decays slowly in anaerobic conditions)

Module D#

Benefits beyond the system boundary might include:

1. Substitution of virgin wood in recycled products
2. Displacement of fossil fuels through energy recovery
3. Carbon storage in long-term landfill scenarios

Practical Requirements for EPDs#

EN 16485 mandates specific information in wood product EPDs:

Declared or Functional Unit#

Wood EPDs must specify:

1. Moisture content (typically 12% or 18%)
2. Density at declared moisture content
3. Volume, mass, area, or length as appropriate
4. Conversion factors between units

Technical Information#

EPDs must include:

1. Wood species or mix
2. Origin information (supporting sustainability claims)
3. Preservative treatments if applicable
4. Structural properties where relevant

Carbon Accounting#

Clear reporting of:

1. Biogenic carbon stored in product
2. Fossil carbon emissions
3. Total GWP including biogenic carbon
4. Separate reporting of biogenic and fossil impacts

Common Challenges in Implementation#

Sustainability Verification#

Demonstrating sustainable forest management for carbon neutrality assumptions requires:

1. Chain of custody certification
2. Documentation of forest origin
3. Evidence of sustainable management practices

Without this verification, more conservative assumptions must be used, potentially showing higher environmental impacts.

Data Availability#

Forestry operations data can be challenging to obtain:

1. Operations vary by region and forest type
2. Multiple suppliers with different practices
3. Long rotation periods complicate averaging

Allocation Controversies#

Different allocation approaches can significantly affect results:

1. Economic allocation favours high-value products
2. Mass allocation treats all outputs equally
3. Energy allocation benefits fuel wood

The choice must be justified and consistently applied.

Biogenic Carbon Communication#

Explaining biogenic carbon in EPDs remains challenging:

1. Negative emissions in production seem counterintuitive
2. Time delays between storage and release aren’t captured
3. Carbon neutrality assumptions require careful explanation

Relationship with Other Standards#

EN 16485 connects with several related standards:

EN 16449 – Calculation of biogenic carbon content in wood Provides the detailed methodology for determining carbon content based on wood species and composition.

EN 15804+A2 – The base PCR for construction products EN 16485 builds on this foundation, with EN 15804+A2 now incorporating many biogenic carbon principles from EN 16485.

ISO 21930 – International construction EPD standard Less prescriptive on biogenic carbon than EN 16485, creating potential inconsistencies for global markets.

National Forest Standards Various countries have additional requirements for demonstrating sustainable forest management.

Implications for Different Wood Products#

Solid Wood Products#

Sawn timber and engineered lumber benefit from:

1. High carbon storage per kg
2. Minimal processing energy
3. Potential for reuse and recycling
4. Clear allocation rules for sawmill co-products

Panel Products#

Particleboard and MDF face challenges:

1. Mixed wood sources complicate sustainability verification
2. Adhesive content affects end-of-life options
3. Higher processing energy than solid wood
4. Complex supply chains

Modified Wood#

Thermally or chemically modified wood requires:

1. Accounting for modification process impacts
2. Adjusted biogenic carbon calculations
3. Special end-of-life considerations

Engineered Wood Products#

Glulam and CLT must address:

1. Adhesive impacts
2. Multiple processing stages
3. Higher value justifying economic allocation
4. Extended service life potential

Future Developments#

The landscape for wood product EPDs continues evolving:

Temporal Carbon Accounting#

Growing interest in accounting for the timing of carbon storage and release, recognising that delayed emissions have less climate impact than immediate ones.

Forest Carbon Dynamics#

More sophisticated methods for assessing forest-level carbon impacts, potentially moving beyond simple carbon neutrality assumptions.

Cascading Use Incentives#

Policy developments encouraging wood reuse and recycling before energy recovery, affecting Module D calculations.

Harmonisation with EN 15804+A2#

As EN 15804+A2 incorporates more biogenic carbon provisions, the relationship with EN 16485 may need clarification.

Practical Guidance from Decerna#

At Decerna, we navigate EN 16485’s requirements daily for timber and engineered wood manufacturers. Key areas where expertise matters:

Biogenic Carbon Modelling: We ensure proper application of characterisation factors and carbon neutrality criteria. This includes verifying sustainable forestry credentials and applying appropriate factors for different scenarios.

Supply Chain Tracing: We help establish chain of custody documentation and map wood sources to support sustainability claims.

Allocation Decisions: We justify and apply consistent allocation approaches across the wood processing chain, ensuring transparency about methodological choices.

Module D Calculations: We model end-of-life scenarios reflecting regional waste management practices and recycling possibilities.

The standard’s complexity reflects wood’s unique position as both a carbon store and renewable resource. When properly applied, EN 16485 enables EPDs that accurately represent wood’s environmental profile, supporting its role in low-carbon construction.

Whether you’re producing sawn timber or advanced engineered wood products, EN 16485 provides the framework for credible environmental declarations that stand up to scrutiny.

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Need help navigating EN 16485 for your wood products? Decerna specialises in EPDs for timber and engineered wood products, ensuring compliance with both EN 15804 and EN 16485 requirements. Contact us to discuss your wood product EPD needs.