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ISO/TR 25078 — Wood and Wood-Based Products: Examples of Calculating Displacement Potentials and Considerations for Further Analyses
Practical Guidance for Quantifying Greenhouse Gas Displacement When Substituting Wood-Based Products for Fossil-Intensive Alternatives
1. Introduction to Displacement Potentials for Wood-Based Products
ISO/TR 25078:2025, prepared by ISO/TC 287 (Sustainable processes for wood and wood-based products), provides calculation examples and background information for determining greenhouse gas displacement potentials when wood-based products are used in place of alternative fossil-intensive materials. The document supports the implementation of ISO 13391-1 and ISO 13391-3, which together define a comprehensive framework for calculating the greenhouse gas dynamics of wood and wood-based products.
The fundamental premise is straightforward: substituting wood-based products for alternatives such as concrete, steel, or plastics can reduce net greenhouse gas emissions because wood stores biogenic carbon and typically requires less fossil energy to produce. However, the actual displacement effect depends on numerous factors including the functional unit definition, system boundaries, geographical context, and market dynamics. ISO/TR 25078 provides worked examples that illuminate these complexities.
Displacement potential is expressed as a unitless factor — tonnes of CO2 equivalent avoided per tonne of CO2 equivalent of biogenic carbon in the wood product. A factor greater than 1.0 indicates that the substitution avoids more emissions than the carbon stored in the wood itself.
2. Calculation Methodology and Worked Examples
The Technical Report presents five detailed calculation examples covering diverse product categories, each illustrating different methodological considerations.
| Example | Wood-Based Product | Alternative Product | Key Methodological Consideration |
|---|---|---|---|
| 1 | Wooden pallet | Plastic pallet | Functional equivalence at product level; end-of-life scenarios |
| 2 | Wood-based bioenergy | Fossil energy sources | Carbon neutrality assumption; time horizon for biogenic carbon |
| 3 | Cross-laminated timber (CLT) floor | Concrete floor | System-level functional unit; multi-functionality of building components |
| 4 | Beverage packaging (carton) | Plastic/glass packaging | Recycling rates and cascading use |
| 5 | Building structure (timber frame) | Steel/concrete structure | Whole-building LCA; foundation implications |
2.1 The Displacement Factor Formula
The displacement factor for a specific use is calculated using the formula: fD,spec = (mE,ap – mE,w) / (wB,w – wB,ap), where mE,ap represents emissions from the alternative product, mE,w represents emissions from the wood-based product, wB,w is the biogenic carbon in the wood product, and wB,ap is biogenic carbon in the alternative. The resulting factor enables direct comparison across different substitution scenarios.
2.2 Data Sources and Quality
ISO/TR 25078 emphasizes that displacement factor calculations must be based on transparently documented data sources. Published scientific articles, LCA studies, and Environmental Product Declarations (EPDs) are the primary data sources. However, the document cautions that EPD comparisons are only valid when based on the same declared unit with demonstrated functional equivalency and when the conditions for comparing EPDs in ISO 14025 are met.
A critical insight from the document is that system boundary selection dramatically affects results. A cradle-to-gate boundary may miss significant downstream emissions differences, while a cradle-to-grave boundary requires assumptions about use phase and end-of-life that introduce uncertainty. Engineers must carefully document and justify their boundary choices.
3. Engineering Design Insights: Factors Influencing Realization
ISO/TR 25078 dedicates an entire clause to factors that influence whether the calculated displacement potential is actually realized in practice — bridging the gap between theoretical calculations and real-world outcomes.
3.1 Market Effects and Rebound
The displacement potential calculated at the product level may not fully materialize due to market effects. For example, if increased use of wood in construction drives up timber prices, this could reduce demand in other sectors, leading to indirect displacement effects. Similarly, improvements in manufacturing efficiency for alternative products could reduce the displacement advantage over time. The document recommends considering these dynamic market interactions when assessing long-term displacement impacts.
3.2 The Time Dimension
Biogenic carbon storage in wood products is not permanent — it depends on the product’s lifespan and end-of-life fate. A wooden pallet may store carbon for only a few years before being chipped and burned for energy, while a CLT building panel may store carbon for decades or centuries. The time horizon chosen for the analysis significantly affects the calculated displacement factor. ISO/TR 25078 recommends transparent reporting of time assumptions and, where possible, using multiple time horizons to test sensitivity.
3.3 Biases and Choice of Product System
The document candidly acknowledges that comparative LCA results can be influenced by methodological choices that favour one material over another. Key sources of bias include: allocation method for co-products, choice of electricity grid mix, assumptions about carbon stock changes in forests, and treatment of biogenic carbon emissions at end-of-life. Engineers conducting displacement analyses should perform sensitivity analyses to test the robustness of their conclusions.
For sustainability engineers and LCA practitioners, ISO/TR 25078 provides a practical toolkit: the worked examples can be adapted to specific product categories, and the discussion of realization factors provides a framework for interpreting calculated displacement factors in their broader economic and temporal context.
4. Frequently Asked Questions
Q1: Can displacement factors be compared across different studies?
Cautiously yes — but only if the functional unit, system boundaries, geographical context, and time horizon are equivalent. The document provides guidance on documenting these parameters to enable meaningful comparisons.
Cautiously yes — but only if the functional unit, system boundaries, geographical context, and time horizon are equivalent. The document provides guidance on documenting these parameters to enable meaningful comparisons.
Q2: How should recycling be handled in displacement calculations?
Recycling extends the carbon storage period and avoids the emissions associated with producing virgin material. ISO/TR 25078 recommends tracking material through cascading use cycles and allocating displacement effects across the product’s multiple life cycles.
Recycling extends the carbon storage period and avoids the emissions associated with producing virgin material. ISO/TR 25078 recommends tracking material through cascading use cycles and allocating displacement effects across the product’s multiple life cycles.
Q3: Is biogenic carbon always considered carbon neutral?
No. The carbon neutrality of biogenic carbon depends on the time horizon and forest carbon dynamics. Sustainable forestry practices that maintain or increase forest carbon stocks support the carbon neutrality assumption, but this must be verified rather than assumed.
No. The carbon neutrality of biogenic carbon depends on the time horizon and forest carbon dynamics. Sustainable forestry practices that maintain or increase forest carbon stocks support the carbon neutrality assumption, but this must be verified rather than assumed.
Q4: How does this document relate to ISO 14040/14044 (LCA standards)?
ISO/TR 25078 builds upon the LCA framework defined in ISO 14040 and ISO 14044, providing wood-sector-specific guidance for applying these general standards to displacement calculations. It does not replace or modify the LCA standards.
ISO/TR 25078 builds upon the LCA framework defined in ISO 14040 and ISO 14044, providing wood-sector-specific guidance for applying these general standards to displacement calculations. It does not replace or modify the LCA standards.
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