The science behind the CO₂e calculator

1What does CO₂e mean?

CO₂e stands for „carbon dioxide equivalents“. Besides CO₂, other greenhouse gases – such as methane (CH₄) and nitrous oxide (N₂O) – also have a climate effect, but to different degrees. To make them comparable, each quantity is, via its Global warming potential (Global Warming Potential, GWP) converted to the climate impact of CO₂.

The GWP values come from the IPCC assessment reports (usual: GWP₁₀₀). By definition, CO₂ has GWP = 1; methane and nitrous oxide have a multiple of that. Thus a single CO₂e value bundles the entire climate impact of a transport.

2Normative framework

The calculation follows the logic of established international standards for transport emissions:

3System boundary: well-to-wheel

What matters is which part of the energy chain is accounted for. The standards distinguish three system boundaries:

The calculator shows the Well-to-Wheel-value as the main result, because only it reflects the entire climate impact – including the fuel upstream chain. For diesel, the upstream chain (WTT) is typically on the order of 15–20 % of total emissions.

4The core formula: tonne-kilometres

The functional unit in freight transport is the Tonne-kilometer (tkm): one tonne of freight over one kilometer. Emissions result from transport performance × emission intensity:

The emission factor is additionally adjusted for the Utilization corrected (see section 5): the lower the utilization, the higher the emission per tonne-kilometer.

The Premium analysis (CSV batch) calculates on a distance- and energy-based basis per shipment: E = total km × EF [kg/km] × utilization factor, including empty km, and then aggregates across the entire fleet.

5Utilization & empty runs

Emissions per tonne-kilometer depend heavily on how full the vehicle is running. A half-loaded truck causes nearly twice as much CO₂e per transported tonne as a full one. The calculator represents this via a Utilization factor from:

In the fleet analysis, utilization is derived from Weight (based on ~24 t payload) and loading meters (based on 13,6 loading meters) is estimated and combined in a weighted manner. In addition, Empty kilometers into the total distance – because the return trip without cargo also causes real emissions. The Empty-run rate (empty km ÷ total km) is thus one of the most important levers for reduction.

6Emission factors by transport mode

For each mode of transport, the calculator stores a representative standard emission factor (Well-to-Wheel, in g CO₂e per tonne-kilometer). The values are on the order of common EN 16258/GLEC defaults and serve for estimation and comparison:

HVO100 (hydrotreated vegetable oil) is modeled as a significantly lower-emission scenario. TTW emissions remain similar to diesel; the major advantage lies in the upstream chain (WTT), which is why HVO counts above all as a Well-to-Wheel argument.

7Distance determination

The distance is the second major lever – and it can be determined precisely. For this, the calculator uses a clear accuracy hierarchy: the better the data source, the more exact the result.

Road route (routing) – the authoritative distance

For the actual driving route, via a routing service (OSRM based on OpenStreetMap) the real road distance is along the road network calculated – not estimated, but the concrete path from A to B (for intermediate stops, as a chain of sub-routes). This is the distance used for the calculation.

Great-circle distance (geodesic) – for control only

Via the Haversine formula the great-circle distance is additionally calculated – the shortest possible distance on the globe. It does not flow into the balance, but serves as a plausibility check on the Detour factor:

If the factor is significantly below (great-circle ≈ road) or above this, the calculator flags the result as conspicuous – a simple but effective data-quality check.

8Limits & data quality

EN 16258 and the GLEC Framework prioritize a data hierarchy: primary consumption data > modeled, activity-based values > standard defaults. For robust customer and tender reports, switching to primary data is advisable – this is exactly where the Premium analysis comes in, by processing real shipment and cost data per tour.

9Scientific studies, standards & sources

The methodology is based on recognized standards, peer-reviewed studies and public emission-factor databases. All links open the respective original source.

Standards & frameworks

• ISO 14083:2023 – Quantification and reporting of GHG emissions arising from transport chain operations. International Organization for Standardization
• EN 16258:2012 – Methodology for calculation and declaration of energy consumption and GHG emissions of transport services. CEN
• GLEC Framework for Logistics Emissions Accounting and Reporting (v3.0). Smart Freight Centre
• GHG Protocol – Corporate Value Chain (Scope 3) Standard, categories 4 & 9. WRI / WBCSD

Scientific studies

• JEC Well-to-Wheels report v5 (Prussi et al., 2020) – well-to-wheel analysis of fuel/powertrain pathways. EU Joint Research Centre
• Rail and waterborne — best for low-carbon motorised transport (2021). European Environment Agency
• Handbook on the external costs of transport (2019) – including climate costs per mode of transport. CE Delft for the European Commission
• IPCC AR6 WG1 (2021), Ch. 7 – global warming potentials (GWP₁₀₀) of CH₄, N₂O and others. IPCC

Emission-factor databases

• HBEFA – Handbook Emission Factors for Road Transport. INFRAS et al.
• Base Empreinte / Base Carbone – emission factor database. ADEME (France)
• TREMOD / transport emission data. German Environment Agency (Germany)

External links; the respective publishers are responsible for content and availability. Standards (ISO, CEN) are subject to a fee and are obtained through the publishers.