Industry-average emission factors give every carrier on a lane the same CO₂ per tonne-kilometre, so a modern, well-loaded vessel and an older, emptier one look identical in your report. ISO 14083 ranks data in a clear order: primary first, then modelled, then default values. Only vessel-level calculations show which carrier actually emits less.

What an average emission factor actually assumes

A default emission factor is an industry average for a mode, vessel type or size class, or trade lane. It fills in when you know nothing specific about the shipment.

The usual recipe looks like this. Take the factor for a "generic container ship", assume the shortest feasible distance, multiply by weight.

Why every carrier ends up looking the same

If every shipment on a lane gets the same factor, the details that drive fuel burn drop out. Vessel size, speed, actual routing and real distance travelled all vanish into one figure.

So two ships on one lane can carry the same number, even when one burns far more fuel per box. You can't book the more efficient vessel, because on paper there isn't one.

What changes when you model the real vessel

When the vessel name or IMO number is known, Lune models the fuel consumption of that specific voyage. Satellite and terrestrial AIS data give the actual route, distance and speed profile. Engine efficiency and fuel type turn that into fuel burned, and fuel burned into CO₂e. The Lune database holds over 16,000 vessels, with data on their engines.

Only when the vessel is unknown do we fall back to industry-average factors, based on trade lane, vessel type and size, and fuel type. Our calculations follow the GLEC Framework and are certified by Smart Freight Centre as ISO 14083 compliant.

What the gap looks like in Lune's data

In our 2025 analysis, "Lune analysed over 100 real shipments, using vessel-specific emission factors and tracked vessel distances via satellite technology. It then re-ran the same calculations using industry-standard inputs: the emissions factor for a 'generic container ship' and the shortest feasible distance."

• 86%: average overestimate from industry-standard calculations
• 0.42 tCO₂e per TEU: average inflation
• 0.47 tCO₂e per TEU: average inflation from the generic container ship factor alone
• ~1.2 tCO₂e per TEU: some cases approached this

Vessel-specific results came out lower and more spread out; standard results clustered high and tight. That spread is where your carrier choices live.

Put a price on it. At an EU carbon price of 85 EUR per tonne, an average overestimate of 0.42 tCO₂e per TEU adds about 36 EUR per TEU for shippers exposed to carbon pricing.

What to ask your carriers or calculation provider

• Is the vessel identified, by name or IMO number?
• Is distance actual (tracked) or assumed (shortest or great-circle)?
• Is each figure disclosed as primary, modelled or default data?
• Is there an audit trail for every leg?

Lune calculates emissions for each shipment leg and shows the data sources and method behind every number, ready for audit.

If your numbers can't tell two carriers apart, what is your carrier choice based on?

See Lune's logistics solution

FAQ

What is the difference between primary, modelled and default data?

Primary data comes from direct measurement, or is calculated from measured values. Modelled data is calculated from shipment and vehicle parameters. Default data is an industry average. Modelled and default data together count as secondary data under ISO 14083 (CLECAT guide to ISO 14083).

Can I compare ocean carriers using average factors?

Only roughly. If every carrier on a lane gets the same factor, any comparison reflects the factor itself. To compare carriers, you need vessel-level calculations based on the actual vessel and voyage.