Every CO₂ figure carries exactly one tier label. A figure can only carry the tier of its weakest input — a Measured primary emission calculated using a grid factor that is Derived produces a Derived result, not a Measured one.
| Tier | What it means | Typical source |
|---|---|---|
| Measured | Based on a supplier-submitted or manufacturer-published Product Carbon Footprint (PCF) document, verified for method and version. | Apple Environmental Progress Report, Dell Product Carbon Footprint, manufacturer PCF database |
| Derived | Calculated from a primary activity figure (kWh, km, kg of material) using a published emission factor. The factor version and source are recorded at calculation time. | IEA World Energy Outlook electricity factors, AIB European Residual Mixes, EU EF 3.1 material factors |
| Estimated | Produced by the mass-estimation cascade when primary data is unavailable — a statistical proxy drawn from products in the same item-group or HS code class. Carries the widest uncertainty band. | ECO360 internal product database, median mass by item group |
Every figure carries a P5–P95 uncertainty interval, not a point estimate. We do not report uncertainty narrower than ±20 % (1σ) at any tier — this matches the MIT PAIA model used by Dell, HP and Lenovo for their own published PCF numbers, whose P5–P95 spread on a single laptop model is approximately 3.5×.
| Tier | Minimum σ (relative) | Source of additional uncertainty |
|---|---|---|
| Measured | ±5 % | Manufacturer methodology variation, functional unit boundaries |
| Derived | ±15 % | Factor vintage, grid mix vs. residual mix, mass estimation error |
| Estimated | ±30 % | Mass proxy accuracy, item-group heterogeneity, factor applicability |
Uncertainty contributions from independent sources are combined in quadrature: σ_total = √(σ_factor² + σ_mass²).
Factors are versioned and dated. A calculation result records the factor set version used at the time of calculation. Factors are never back-applied to existing results when a new version is published.
| Factor type | Source | Version / vintage |
|---|---|---|
| Electricity — market-based | Association of Issuing Bodies (AIB) European Residual Mixes | AIB ERMs 2023, 2024, 2025 |
| Electricity — location-based | IEA World Energy Outlook | IEA WEO 2024 |
| Material — EU average | EU Environmental Footprint 3.1 (JRC / EC) | EF-3.1-2024 |
| Fuel combustion | IPCC 2019 Guidelines for National Greenhouse Gas Inventories | IPCC 2019 global |
| Device CO₂ — Measured | Manufacturer published PCF documents (Apple, Dell, HP, Lenovo) | Per-document version and publication date |
Unless stated otherwise, a device CO₂ figure covers cradle-to-gate manufacturing (Scope 3, Category 1: purchased goods and services). Use-phase electricity consumption is calculated separately and reported as Scope 2 when a grid factor is available. End-of-life (Category 12) is reported separately using Eurostat EU-average treatment shares when primary data is absent.
We do not aggregate Scope 1, 2 and 3 into a single number. A single-number "carbon footprint" across all three scopes combines quantities that are typically double-counted in supply chains and should not be summed without an explicit methodology statement naming the double-counting convention used.
Every workbook produced by the ECO360 pipeline records:
Given the same input file and factor set version, the ECO360 engine produces bit-identical output. This is verified by an automated reproducibility test that is part of the CI suite on every code change.
When an error is found in a published figure, we:
To report a potential error, email data@eco360.ai with the product name, the figure in question, and the source you believe is more accurate.
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