WI-CO2 v1.0.0 · EN 15804+A2 / EN 15978 module logic, biogenic carbon per EN 16485
Carbon Intelligence.
A dynamic whole-life carbon model, module by module. Biogenic carbon is stated separately, as EN 16485 requires — it is never netted into the fossil total to make a species look better.
Norway Spruce over 15 years is a modelled net 3.3 kg CO2e/m² (A1–A3 fossil, A4, B2, C3, C4), storing 18 kg CO2e/m² of biogenic carbon separately (EN 16485), for a reuse (element recovered intact) end-of-life route.
This is a modelled estimate assembled from published default factors, not a project-specific EPD. Where a manufacturer's EPD exists, its declared values must be used instead.
Module stack (A1–A3 · A4 · B2 · C3 · C4)
A1-A3
187 kg
Product stage (fossil)
A4
71 kg
Transport to site
B2
60 kg
Maintenance (recurring)
C3
4 kg
End-of-life processing
C4
5 kg
End-of-life disposal
Biogenic (separate)
1,815 kg
EN 16485 — stored, not netted into the total above.
Module D (beyond boundary)
-770 kg
Credit for a full service-life-equivalent virgin timber element displaced by the reused element, per EN 15804 Clause 6.3 Module D methodology. This is the largest and most assumption-sensitive term in the model.
What dominates this resultSensitivity fold
Product stage (fossil) (A1-A3) accounts for 57.2% of the modelled fossil total for this scenario. A1–A3 processing is largely fixed by species and modification route.
- A1-A3 — Product stage (fossil)57.2%
- A4 — Transport to site21.7%
- B2 — Maintenance (recurring)18.3%
- C4 — End-of-life disposal1.5%
- C3 — End-of-life processing1.2%
Every factor used, with its sourceData table
| Factor | Value | Source |
|---|---|---|
| Carbon fraction of oven-dry wood | 0.5 kg C / kg dry wood | Default carbon fraction for softwood and hardwood per EN 16449 Clause 4, converted to CO2 by the molar mass ratio 44/12. — CEN — European Committee for Standardization, EN 16449:2014 — Wood and wood-based products. Calculation of the biogenic carbon content of wood and conversion to carbon dioxide (2014) |
| A1–A3 processing (fossil) | 85 kg CO2e / m³ | Cradle-to-gate fossil emissions for sawing, kiln-drying and planing of solid softwood/hardwood sections, mid-point default from published European softwood-sawn-timber EPDs under EN 15804+A2 (declared unit 1 m³, A1–A3 modules only). Project-specific EPDs must supersede this default. — ISO, ISO 21930:2017 — Core rules for environmental product declarations of construction products and services (2017) |
| A1–A3 modification adder — none | 0 kg CO2e / m³ | No modification process; no adder beyond base processing. — CEN — European Committee for Standardization, EN 16449:2014 — Wood and wood-based products. Calculation of the biogenic carbon content of wood and conversion to carbon dioxide (2014) |
| Road freight (>32 t truck) | 0.09 kg CO2e / t·km | UK Government GHG Conversion Factors for Company Reporting, rigid/articulated HGV average freighting factor, well-to-wheel. — ISO, ISO 21930:2017 — Core rules for environmental product declarations of construction products and services (2017) |
| Maintenance cycle impact | 0.6 kg CO2e / m² per cycle | Cradle-to-gate impact of one exterior wood-coating maintenance cycle (product + site application), mid-point default from published exterior wood-coating EPDs, excluding transport to site (accounted separately if distance is significant). Untreated species scored 0 for this module since they carry no scheduled recoat. — ISO, ISO 21930:2017 — Core rules for environmental product declarations of construction products and services (2017) |
| Reuse (structural or cladding element recovered intact) | 4 kg CO2e / m³ (C3/C4 processing only) | De-installation, inspection and re-grading impact only; assumes the element re-enters service and its stored biogenic carbon remains sequestered. Mid-point default derived from EN 15804 Module D methodology for reused structural timber. — CEN — European Committee for Standardization, EN 15804:2012+A2:2019 — Sustainability of construction works. Environmental product declarations. Core rules for the product category of construction products (2019) |
| Module D — avoided burden from displaced virgin material | -350 kg CO2e / m³ | Credit for a full service-life-equivalent virgin timber element displaced by the reused element, per EN 15804 Clause 6.3 Module D methodology. This is the largest and most assumption-sensitive term in the model. — CEN — European Committee for Standardization, EN 15804:2012+A2:2019 — Sustainability of construction works. Environmental product declarations. Core rules for the product category of construction products (2019) |
Comparison across species, same brief
Same area, thickness, transport distance, mode, treatment and end-of-life route applied to every species so the comparison isolates the material choice. Brand-neutral: this ranks species, not suppliers.
- Norway Spruce3.3 kg CO2e/m²
- Douglas Fir4 kg CO2e/m²
- Scots Pine (heartwood)4 kg CO2e/m²
- Siberian Larch4.7 kg CO2e/m²
- Western Red Cedar5 kg CO2e/m²
- Sweet Chestnut5.3 kg CO2e/m²
- European Oak5.5 kg CO2e/m²
- Iroko (FSC certified)6 kg CO2e/m²
- Robinia (Black Locust)6.2 kg CO2e/m²
- Thermally Modified Pine6.4 kg CO2e/m²
- Thermally Modified Ash7.3 kg CO2e/m²
- Acetylated Radiata Pine8.9 kg CO2e/m²
Machine-readable: GET /api/public/v1/carbon · CC BY 4.0. Modelled estimate — not a substitute for a project-specific EPD.