Shipment Emissions Calculation for Forwarders: ISO 14083 and the GLEC Framework in Practice

A shipment emissions figure is the greenhouse gas footprint of one consignment from the point it leaves the shipper to the point it reaches the consignee, expressed in kilograms or tonnes of CO2e. The international method is ISO 14083:2023, applied through Smart Freight Centre's GLEC Framework. For a forwarder the practical rules are short: count well-to-wheel, not just the exhaust; split the journey into legs and hubs; use the shortest feasible distance, not the route the cargo happened to take; prefer carrier data over defaults; and divide shared transport by tonne-kilometres. What the customer then does with the figure (Scope 3 categories, CSRD scope, US rules) is covered from the shipper's side in freight emissions reporting in 2026.

ISO 14083 and the GLEC Framework: what each one does

ISO 14083:2023, published in March 2023, sets the method for quantifying and reporting greenhouse gas emissions from transport chains: every mode, plus the hubs in between. The GLEC Framework is Smart Freight Centre's practitioner's manual for it. As of October 2026 the current edition is version 3.2, released in October 2025 as a minor annual update (mainly the data sources behind its fuel emission factors, plus a new air pollutant module). It supplies the default emission intensities you use when a carrier gives you nothing better, and sets out what a report must contain. Check for a newer edition before relying on any figure.

If a report claims conformity with ISO 14083, the GLEC Framework says it should state that the results have been established in accordance with ISO 14083:2023, and any deviation from the method must be highlighted, justified and its effect described.

Well-to-wheel, not tank-to-wheel

Both documents split emissions in two. Tank-to-wheel (TTW), or operational emissions, is what the vehicle or hub equipment emits when it uses its energy (at sea, tank-to-wake). Well-to-tank (WTT), or energy provision emissions, is producing and delivering that fuel or electricity. Together they make well-to-wheel (WTW), and ISO 14083 requires WTW. The common mistake is to send a customer a TTW figure because that is what a fuel-burn calculation produces. In the GLEC v3.2 industry-average figure for dry containers, energy provision is 12.7 of 71.7 g CO2e per TEU-km, roughly 18% of the total. For electric legs TTW can be near zero while WTT carries the whole footprint, so a TTW-only report makes an electric truck look emission-free. Report CO2e (all greenhouse gases as a CO2 equivalent), not CO2 alone.

Break the shipment into transport chain elements and hubs

A transport chain runs from consignor to consignee and is made of transport chain elements (TCEs). Every change of vehicle starts a new element, and hubs (a CFS, a terminal, a cross-dock, a warehouse) are elements with zero distance.

For each element: work out the transport activity (tonnes multiplied by kilometres, so tonne-km), find the emission intensity for that kind of operation, and multiply. For a hub the activity is the tonnes passing through, multiplied by an intensity in kg CO2e per tonne.

Two details trip people up. The mass includes the packaging the shipper provided but not the load carrier, so container tare and air ULDs do not count as cargo. And if you only know the shipment in TEU, the GLEC Framework allows an assumed 10 tonnes per TEU (6 for light cargo, 14.5 for heavy), provided you document it.

Distance: shortest feasible, great circle and the adjustment factor

The intuitive approach is to measure the route the cargo actually took. That is not the method. For each shipment's transport activity, ISO 14083 and the GLEC Framework use the shortest feasible distance (SFD): the shortest practical route for that kind of vehicle given real constraints such as vehicle size and road type, usually from route-planning software or a port-distance table. Air uses the great circle distance (GCD) between airports.

The reason is consolidation. A truck on a milk run or a vessel calling at several ports travels further than any one consignment needs to; that network effect belongs in the operation's emission intensity, not in each shipment's distance. Where you only have actual distance, a distance adjustment factor (DAF) reconciles the two:

• Ocean container: GLEC cites the Clean Cargo recommendation of a DAF of 1.15, because actual container ship distances were on average 15% longer than the shortest feasible port-to-port route.
• Air: the GLEC default air intensities already include a +95 km adjustment for diversions and out-of-route flying. Apply them to the great circle distance without adding the 95 km again.

Red Sea diversions are the awkward case: a Cape of Good Hope routing runs thousands of kilometres longer than Suez (background in Red Sea, Cape routing and the 2026 capacity squeeze). Whether the longer route is the feasible one is a judgement the standard does not settle for you. Ask the carrier what its figure is based on, pick one approach, and state it.

Default factors versus carrier primary data

Every regime ranks primary data from the operator first, modelled data next and default values last (the shipper-side post linked above explains the ranking). For a forwarder, what matters is where each kind comes from and what you record.

The GLEC reporting rules ask you to state the share of primary and secondary data, and to split secondary into modelled and default. Mixed sources are normal. Watch for carrier figures quoted TTW or as CO2 only: the GLEC Framework notes that IMO operational indicators are TTW CO2, so the WTT share must be added and the result scaled to CO2e before they fit.

A legal point limits how hard you can push suppliers. Since the EU's 2026 Omnibus changes to the CSRD, companies in a reporting company's value chain with up to about 1,000 employees can decline requests that go beyond the voluntary SME standard. Many hauliers are small, so plan on modelled or default data for some road legs.

Allocating a shared container or truck: tonne-kilometres

LCL and groupage share a vehicle by design. The rule is to allocate emissions by transport activity: each consignment's mass multiplied by its shortest feasible distance on that element, as a share of the total tonne-km on it. If every consignment in a box travels the same port-to-port leg, that reduces to a share by mass.

Three points cause disputes:

• Container factors are usually per TEU-km. Apply one to the box and divide by mass, and the cargo inside bears the box's empty space. Convert it to a per tonne-km figure with the 10-tonne default, and a light box looks much cleaner than it is. The worked example shows the difference.
• Mass, not revenue or volume. ISO 14083 and GLEC allocate freight by mass. If you depart from that for a volume-limited operation, treat it as a deviation: document and justify it.
• Be consistent. The GLEC Framework says allocation principles should stay constant over time and be documented. Changing method between quarters makes your customer's year-on-year trend meaningless.

Base the split on the same consignment records you use to divide the freight cost; how the consolidation itself is bought and run is covered in LCL co-loading and consolidator relationships.

A worked example: one LCL consignment, Port Klang to Duisburg

This example is illustrative. Distances are rounded assumptions and the factors are example values, in the same order of magnitude as published defaults, chosen for readable arithmetic. Do not reuse them: take real factors from the current GLEC tables or, better, the carriers involved.

Assumptions: Shipper A's consignment weighs 4 tonnes with packaging. It is trucked 40 km from Shah Alam to the forwarder's container freight station (CFS) at Port Klang, consolidated into a 40-foot container (2 TEU) holding 12 tonnes from three shippers, shipped an assumed 15,000 km to Rotterdam (Suez routing), deconsolidated at a CFS and trucked 230 km to Duisburg. All factors are well-to-wheel.

What the example shows:

• The ocean leg dominates at about 87%, so that is where carrier primary data is worth chasing. The hubs add under 2%, but omitting them is still a deviation to declare.
• The conversion choice cuts the ocean leg by 40%. Had you converted the 70 g per TEU-km factor to 7 g per tonne-km using the 10 tonnes per TEU default, the ocean leg would come out at 4 t x 15,000 km x 7 g = 420 kg. The box carries only 6 tonnes per TEU, so the per-TEU method assigns its empty space to the cargo. State which you used; mixing them across customers is the real problem.
• TTW-only would understate it. With about 18% of the ocean factor being energy provision, as in the GLEC industry average, a TTW figure for that leg would be about 576 kg instead of 700.

For a quick order-of-magnitude check, the estimators in our free freight tools give an indicative figure by mode, weight and distance: an estimate, not an ISO 14083 report.

What customers need the number for

Most requests come from one of four places: a customer's own Scope 3 inventory (purchased freight usually sits in Category 4, the upstream transportation category), a science-based target or CDP response, a tender that scores sustainability, or a customer comparing routings. Emissions questions often appear in RFQs; answering them is part of responding to a freight RFQ.

On regulation, as of October 2026:

• CSRD now applies only to companies with more than 1,000 employees and more than 450 million euro net turnover, after the 2026 Omnibus directive, so fewer customers are directly obliged.
• CountEmissionsEU is no longer a proposal. It was adopted as Regulation (EU) 2026/1030 on 29 April 2026, published in the Official Journal in May and entered into force in June 2026. Its substantive rules apply from December 2030. It does not require anyone to calculate emissions. It requires that anyone who calculates and discloses emissions for a transport service within its scope (voluntarily, under contract or under another law) uses its common method, built on EN ISO 14083:2023 and prioritising primary data. Before then the Commission is to build EU databases of emission factors and default intensities and a free calculation tool. Larger entities face independent verification; SMEs are exempt but may opt in. A forwarder already calculating to ISO 14083 is most of the way there.

The EU ETS surcharge is not your customer's carbon footprint

Customers sometimes ask you to turn the ETS line on the ocean invoice into a carbon figure. It does not work. The surcharge is the carrier's cost of EU allowances for the voyage emissions the ETS covers: measured at the ship (tank-to-wake), counting only half of a voyage between an EU and a non-EU port, allocated to containers by the carrier's own method and priced at the allowance market. A shipment footprint is well-to-wheel, door to door including hubs, and allocated by tonne-km. Keep the two apart; the surcharge is explained in EU ETS and FuelEU surcharges. The carbon embedded in the goods themselves is a third, unrelated calculation under CBAM.

What to put in an emissions statement for a customer

• The consignment or period covered, and the elements and hubs included (any excluded, with the reason).
• Total kg CO2e well-to-wheel (with the TTW and WTT split if asked), plus emissions and intensity per mode and the distance type used.
• Data sources per element, the primary, modelled and default shares, and the allocation method for shared transport.
• The statement of conformity with ISO 14083:2023 if you claim it, and any deviations with their effect.
• Gross emissions: any offsets reported separately, never netted off.

What to do next

1. Map your three busiest lanes into transport chain elements, including every CFS, terminal and warehouse.
2. Ask the carriers on those lanes what emissions data they supply, on which basis (WTW or TTW, CO2 or CO2e) and how they allocate.
3. Pick one default source for the gaps, record its edition, and decide once how to convert per-TEU factors for consolidated cargo.
4. Write a one-page method note to attach to every emissions statement.

More than 29,300 logistics companies are searchable by country and service in the CargoLinked directory, and the public requests board lists freight that shippers have posted for forwarders to quote on directly. When a shipper asks about emissions, a written method is the answer to have ready.

This article is general information, not legal, regulatory, tax or environmental reporting advice. Standards, default factors and EU rules change; check the current ISO 14083 text, the latest GLEC Framework edition from Smart Freight Centre and the official EU legislation, and confirm your approach with a qualified sustainability or legal professional before relying on it.