--- title: "How Orbit calculates transport emissions (method 2026.11)" description: "Read how Orbit calculates transport emissions, allocates them to shipments, and labels the quality of the input data." url: "https://support.staging.orbit.do/en/advanced-features/emissions-method-2026-11" locale: "en" apps: ["mission"] lastReviewed: "2026-10-12" --- # How Orbit calculates transport emissions (method 2026.11) Read how Orbit calculates transport emissions, allocates them to shipments, and labels the quality of the input data. Orbit calculates transport emissions for shipments, legs and tours. This page explains the method version 2026.11, including the sources, assumptions and data-quality labels behind each result. ## 0. Scope and units Results are expressed as well-to-wheel (WTW) kilograms of carbon dioxide equivalent (CO₂e), with tank-to-wheel (TTW) and well-to-tank (WTT) values shown separately. The method also reports transport activity in tonne-kilometres (tkm) and an intensity in grams of CO₂e per tkm. It follows ISO 14083:2023, using the GLEC Framework v3.2 as a guide. Offsets are not deducted. ## 1. Transport chain elements A leg on a tour is a road transport chain element (TCE). A cross-dock between two legs of a shipment is a hub TCE. A shipment result is the sum of its TCEs. ## 2. Which calculation applies to a leg Method 2026.11 does not accept carrier-provided ISO figures. For each leg, Orbit uses the first applicable method in this order: 1. For a leg whose transport mode is not `directTrip`, the category calculation in section 6. 2. For a `directTrip` leg on a tour, the tour calculation in section 3. 3. For a `directTrip` leg without a routed tour, the per-tkm floor in section 5. ## 3. Mode 1: energy for a tour Orbit estimates energy for each arc between consecutive tour stops, then adds the arc values. For each arc, the EMEP/EEA consumption curve uses the vehicle segment, emissions class, on-board load percentage and speed, multiplied by the arc distance. The vehicle segment comes from the assigned vehicle's maximum total weight, or from the tour's vehicle class when there is no vehicle. Axle count distinguishes rigid and articulated vehicles; an articulated vehicle above 32 tonnes is assumed to be in the articulated band. If the vehicle's emissions class is missing, Orbit uses Euro VI. On-board mass for an arc is divided by the vehicle's payload capacity, or the vehicle class's capacity when there is no vehicle. An empty arc, including a depot start or return represented on the tour, uses empty-vehicle consumption. Empty distance outside the tour is not added: empty kilometres are counted as they appear on the tour. Speed is the arc distance divided by its routed travel time, with a zero-percent road slope. Orbit uses planned tour distances. The EMEP/EEA guidebook has no load dimension for vans, so the DESNZ 2026 van correction is applied; its published van data make that correction neutral. For a refrigerated or frozen vehicle, Orbit applies the DESNZ 2026 refrigerated-to-standard consumption ratio for its vehicle class. Refrigerant leakage is excluded. Orbit converts tour energy to fuel or electricity using the energy-carrier factors in section 4. This is modelled tour energy; it does not add a round-trip or empty-trip uplift beyond the distances on the tour. ## 4. Energy, emissions and allocation Orbit multiplies the tour's modelled energy by the energy-carrier factors to calculate TTW and WTT CO₂e. Until permission to publish GLEC-derived energy-carrier values is recorded, the factors are from JEC WTT v5. Diesel, petrol, liquefied petroleum gas, compressed natural gas, liquefied natural gas, hydrotreated vegetable oil, synthetic diesel, electricity and hydrogen have these TTW and WTT factors, in grams of CO₂e per megajoule: | Energy carrier | TTW | WTT | | -------------------------- | ---: | ----: | | Diesel | 73.2 | 18.9 | | Petrol | 69.5 | 17.0 | | Liquefied petroleum gas | 65.4 | 7.8 | | Compressed natural gas | 55.2 | 15.1 | | Liquefied natural gas | 56.4 | 16.6 | | Hydrotreated vegetable oil | 0 | 11.1 | | Synthetic diesel | 2.7 | 27.5 | | Electricity | 0 | 110.1 | | Hydrogen | 0 | 113.0 | Orbit allocates the tour result to each shipment-leg using its declared mass multiplied by its shipment distance (SFD), divided by the total of those products across the tour's shipment-legs. Declared mass is used. There is no distance-adjustment factor in Mode 1: the tour's own distance carries the energy, and SFD is used only to calculate each leg's share. ## 5. Per-tkm floor for a direct trip without a routed tour When a `directTrip` leg has no routed tour, Orbit multiplies its mass and SFD by a per-tkm intensity for the vehicle segment. The floor is the GLEC Framework v3.2 Module 2 Europe road method. Its published intensity incorporates assumptions for load, empty distance and SFD uplift. Orbit applies the published intensity directly and labels the result as a default. The numerical floor factors are not included here while permission is pending. ## 6. Mode 2: network legs For `partLoad` and `groupage` legs, Orbit multiplies mass and SFD by the category intensity from GLEC Framework v3.2 Module 5, Table 3. The intensity distinguishes ambient and temperature-controlled transport. Groupage also uses the source's distance adjustment. These results are labelled as category defaults. The numerical category factors are not included here while permission is pending. There is no parcel default in this method version. Orbit records `no default available` and does not calculate a figure. A `directTrip` leg in Mode 2 follows the direct-trip calculation in section 3 or section 5. ## 7. Hubs For a cross-dock between two shipment legs, Orbit calculates emissions from the shipment mass and the GLEC Framework v3.2 Table 3 hub intensity. The source distinguishes ambient from mixed or temperature-controlled handling. The result is labelled as a default. The numerical hub factors are not included here while permission is pending. ## 8. Data-quality labels Each result carries the factor-set and method versions, a primary-data share, and labels for the inputs used. In method 2026.11, the primary-data share is 0%. | Input | Source label | | ------------------------------------- | ------------------------------------------------------- | | Distance used for tour energy | `tourPlanned` | | Shipment distance used for allocation | `sfdRouted` or `estimated` | | Vehicle | `vehicle`, `vehicleClass`, `default` or `notApplicable` | | Energy | `tourModel`, `floorDefault` or `categoryDefault` | | Transport-mode source | `product`, `carrier`, `adapter` or `default` | | Temperature treatment | `none` or `defaultUplift` | | Mass | `declared` | The `carrierProvided` energy label is reserved in the data model but is not emitted in method 2026.11 because carrier-figure ingestion is not supported. The shipment distance approximates the shortest feasible route using the routed pickup-to-dropoff distance. If routing fails, Orbit uses a κ-based beeline estimate and labels it `estimated`; the estimate is not a strict shortest route. Each input also has a quality category: `primary`, `modelled` or `default`. A missing mass is flagged as `massMissing`. If a shipment-leg has no mass, it receives no figure or allocation share; the other legs share the available tour result and are marked to show that co-loaded mass is missing. ## 9. Worked example A 12-tonne rigid diesel Euro VI vehicle makes a Hamburg tour carrying three shipments: A weighs 2 tonnes, B weighs 1 tonne and C weighs 3 tonnes. The tour runs 65 km from the depot to A with 6 tonnes on board, 40 km from A to B with 4 tonnes, 70 km from B to C with 3 tonnes, then 20 km to the end with no load. The energy model calculates each arc from its load and routed speed. For 95 litres of diesel, the JEC WTT v5 fallback factors give approximately 296 kg WTW, split into 235 kg TTW and 61 kg WTT. The SFDs are 65 km for A, 95 km for B and 160 km for C. Their transport activity is 130, 95 and 480 tkm respectively, or 705 tkm in total. Orbit allocates approximately 54.5 kg to A, 39.8 kg to B and 201.3 kg to C. Each receives an intensity of about 419.4 g/tkm. If C's mass is missing, C receives no figure. A and B share the tour's 296 kg in proportion to 130:95. This example does not include the per-tkm floor or groupage category variants while permission for their GLEC-derived figures is pending. ## 10. Sources and versions The method is version 2026.11, with factor set `orbit-v1-2026-11`. Its sources are: * EMEP/EEA Guidebook 2023, Appendix 4 (May 2026), COPERT 5.10.1, for vehicle energy consumption. * JEC Well-to-Tank v5 (EUR 30269 EN, 2020), for the open energy-carrier factors. * UK DESNZ 2026, for van and temperature-control adjustments. * GLEC Framework v3.2 (October 2025), Modules 1, 2 and 5 and Table 3, for energy-carrier, floor, category and hub methods. Its numerical values are omitted pending permission. ## Source attributions Contains data from the EMEP/EEA air pollutant emission inventory guidebook 2023, Appendix 4 (May 2026), © European Environment Agency. JEC Well-to-Tank report v5, Prussi et al., EUR 30269 EN, 2020, CC BY 4.0. Values derived and combined by Orbit. Contains public sector information licensed under the Open Government Licence v3.0 GLEC Framework v3.2 (October 2025) is cited as the method source. Its numerical values, including the groupage distance adjustment, are omitted pending permission. These calculation results have been established in accordance with ISO 14083:2023 **Q: Why is a result labelled as a default?** A default uses a published per-tkm floor, transport-category intensity or hub intensity instead of tour energy calculated from a routed tour. **Q: What happens if a shipment's mass is missing?** That shipment-leg has no emissions figure or allocation share. The other shipment-legs on the tour share the available result, and their data-quality labels show that co-loaded mass is missing. **Q: Does the tour include empty distance outside its stops?** No. The calculation includes the empty arcs represented on the tour. It does not add depot approach or return distance that is outside the tour.