Two carriers can move the identical load on the identical lane and report very different CO₂ figures — purely because of how the number was calculated. That single fact explains most of the confusion in Scope 3 logistics reporting, and it is the reason a figure alone is no longer sufficient. Under the GLEC Framework and ISO 14083, emissions can rest on primary data — what the vehicle actually burned — on modelled data using real distance with default factors, or on default industry averages. The further you sit from primary data, the more your reported emissions are an estimate, the more calculatory buffer they carry, and the harder they become to defend to an auditor. For an era where a transport CO₂ number went into a report and nobody asked how, that was fine. That era is ending. Book a 30-minute session and bring one lane's emissions figure — we'll rebuild it in Fleet Rabbit from your own shipment records and show you which data tier you are actually reporting on.
TOP 5 · SCOPE 3 LOGISTICS
Scope 3 Logistics Emissions for Manufacturers
Activity data captured as shipments move, mode and distance factors applied correctly, boundary decisions made deliberately, and a calculation record an auditor can follow.
Carrier A
Default factors
Estimate
≠
Carrier B
Primary fuel data
Measured
Identical load. Identical lane. Different reported CO₂e. The gap is the calculation method, not the performance — which is why default-factor figures cannot be used to compare carriers against one another.
Two Documents, Two Jobs
The acronyms get used interchangeably and they do different things. Getting this straight makes everything downstream simpler.
ISO 14083
The international standard for quantifying and reporting greenhouse gas emissions from transport chain operations. It defines how to allocate emissions across the legs of a multimodal shipment, how to handle hub and transshipment emissions, how to treat empty running, and which data quality tiers count as compliant. It supersedes the earlier European standard.
In one lineThe rules for applying the numbers
GLEC Framework
The industry-standard methodology from Smart Freight Centre, supplying emission factors for road, sea, rail and air freight aligned with ISO 14083. Version 3.2 is the current edition as of 2026, with a further version in draft. It takes a bottom-up approach and is approved by the GHG Protocol.
In one lineThe numbers themselves
The method that is no longer accepted
Both the GLEC Framework and ISO 14083 are more prescriptive than general GHG accounting and do not accept the spend-based calculation methodology, because of its poor reliability for transport emissions. If your current transport figure is derived from freight spend multiplied by an intensity factor, it will not survive contact with either standard — and rebuilding it on activity data is the work, not a refinement of it.
Five Ways to Get It Defensible
Ordered by effect on auditability. The first is structural and the rest follow from it.
01Capture activity data as the shipments move
Mass, origin, destination, mode and vehicle configuration recorded per leg at the time — not reconstructed twelve months later from invoices. This is the difference between a filing built on primary data your auditors can trace and a scramble to rebuild a year of movements from whatever survived in the transport system.
Why firstEverything else is a method choice. This one is a data availability choice, and it cannot be made retrospectively
02Climb the data hierarchy where it matters
Use primary data wherever you can and fall back down the tiers only when you must. The more primary data in the calculation, the more accurate and more defensible the result. You will not get primary data everywhere, so prioritise your highest-volume lanes and accept modelled data on the tail.
Practical ruleRecord the tier used per leg, so the mix is visible rather than implied
03Get load factor and empty running right
These are the two adjustments that drive the largest deltas in the whole calculation. A half-empty truck and a full one on the same lane produce very different intensity per tonne-kilometre, and empty return legs have to be treated according to the standard rather than quietly excluded.
Practical ruleIf these two are estimated, say so — they move the answer more than anything else you might refine
04Report well-to-wheel, not just combustion
Well-to-wheel is the sum of fuel production and fuel combustion — the upstream well-to-tank component plus the tank-to-wheel component. Both CSRD Scope 3 reporting and the GLEC Framework require the well-to-wheel basis, so a combustion-only figure is not merely conservative, it is incomplete.
Practical ruleState the basis explicitly on every reported figure, because the two are not comparable
05Stamp the factor vintage on every calculation
Emission factor sets are revised — European road freight intensity values update as underlying research is published, and harmonised factor databases continue to develop. An inventory calculated against an earlier factor vintage stays auditable only if the version it used is recorded alongside the result.
Practical ruleVersion-stamp the factor set and the global warming potential basis used, per reporting period
Data tier check
Most teams do not know which tier their number actually sits on.
Bring one quarter of shipment records to a short call and we'll rebuild the calculation in Fleet Rabbit leg by leg — showing which legs have primary data, which fall back to modelled, and where a default average is carrying more weight in your total than anyone realises. You leave with the tier mix documented, which is the first thing an assurance provider will ask for.
The Calculation Spine
Bottom-up, from the smallest unit the standard recognises. Understanding this structure is what makes the boundary decisions later obvious rather than arbitrary.
1
Start at the transport chain element
The smallest unit the standard works with — a single leg, on a single mode, with a single vehicle configuration. A multimodal shipment is a series of these rather than one movement.
2
Build the activity figure
The spine is the tonne-kilometre: one tonne of cargo carried one kilometre. Cargo mass multiplied by leg distance produces the activity quantity that the factor is applied to.
3
Apply the right intensity
Emissions equal mass in tonnes, times distance in kilometres, times the well-to-wheel intensity for that vehicle class, load factor and fuel. The intensity is where vehicle class and load factor enter the arithmetic.
4
Add the hubs
Hub operations — loading, cross-docking, transshipment — get their own category and their own emissions. This is one of the framework's most distinctive contributions and the element most often left out of a home-built calculation entirely.
5
Aggregate to the transport chain
Reports can be provided at one or more levels of detail, from individual elements up to the whole chain. For a single-shipment disclosure, element-level detail is what a customer or auditor will expect.
On distance, be explicit about which convention you used. Default-factor calculations typically use a shortest feasible distance between points for the mode, while a distance adjustment factor can be applied where odometer data is available. Two calculations using different distance conventions are not comparable, and the difference is rarely small on multimodal chains.
Boundary Decisions
Four decisions that determine what lands in your inventory. Make them explicitly and write them down, because every one of them will be questioned.
← Swipe to see all columns →
| Decision | The distinction | Why it matters |
|---|---|---|
| Category 4 or Category 9 | Upstream transportation and distribution against downstream | Inbound to the plant and outbound finished vehicles sit in different categories and get disclosed separately |
| Whose Scope is it | Contracted transport is your Scope 3; a carrier's own fleet is their Scope 1 and 2 | The same physical movement is reported by both parties, in different places, without being double counting |
| Chain operator or activity operator | Who organises the chain against who performs the movement | Determines which party is responsible for reporting which portion of a multi-party chain |
| Hubs in or out | Transshipment, cross-dock and handling emissions | In scope under the standard, and frequently omitted — which understates multimodal chains materially |
On the regulatory horizon
A simplified set of European reporting standards is expected in late 2026 for mandatory use from financial year 2027, and early drafts suggest category-level Scope 3 reporting stays while aggregation becomes more flexible. That may reduce the short-term paperwork. It does not reduce the pressure arriving from customers and tender processes — and a separate EU framework is establishing a single methodology aligned with the international standard so that door-to-door figures are comparable across modes, which is precisely the reference point auditors and customers will use.
What an Audit-Ready Record Contains
Six fields per calculation. Together they let someone else reproduce your number, which is the only functional definition of auditable.
Activity quantities per legMass, origin, destination, distance and the distance convention used. The inputs, not just the output.
Mode and vehicle configurationPer element, since the intensity applied depends on it. "Road" is not a vehicle configuration.
Data tier and sourcePrimary, modelled or default, recorded per leg with any fallback shown explicitly rather than buried in a total.
Factor set and versionWhich framework version and which regional factor set, with the global warming potential basis stated.
Load factor and empty running treatmentThe two largest swing variables. Whether measured or assumed, and on what basis.
Hub emissions, itemisedSeparately from transport legs, so the chain reconciles element by element rather than only in aggregate.
A useful test before you file anything: hand the record to someone who was not involved and ask them to reproduce the figure. If they cannot, an assurance provider will not be able to either — and the conversation you have then is considerably more expensive than the one you would have had now.
Where Reductions Actually Come From
Measurement is not the objective. Four levers move the number, and three of them are decisions a plant logistics team already owns.
1Shorten the distanceReducing distance between supplier and plant, including through local sourcing. Structural, slow, and the largest single lever available.
2Improve load factorFuller loads on the same movements. Directly reduces intensity per tonne-kilometre and reduces freight cost at the same time, which makes it the easiest to fund.
3Cut empty runningFill the return leg. The least defensible category of transport emissions because nothing moves, and one of the few reductions that is auditable per route and date.
4Shift mode where the lane allowsReplacing higher-emitting modes on lanes that can absorb the transit. Real, but constrained by the same feasibility tests that govern any modal decision.
Enterprise demo
Twenty minutes on your inbound lanes and one quarter of shipment data
We'll build the element-level calculation in Fleet Rabbit — activity per leg, tier per leg, hub emissions itemised, factor version stamped — and show you the record an assurance provider would ask for alongside the number itself. You keep the calculation structure either way, and most teams discover their largest lane is also their weakest data.
Frequently Asked Questions
Can we calculate transport emissions from freight spend?
Not under the standards that matter here. Both the GLEC Framework and ISO 14083 are more prescriptive than general GHG accounting and do not accept the spend-based calculation methodology, because of its poor reliability for transport emissions specifically. If your current figure comes from spend multiplied by an intensity factor, plan to rebuild it on activity data — mass, distance, mode and vehicle configuration per leg. That rebuild is the project, and starting it before an assurance cycle rather than during one is considerably cheaper.
What is the difference between ISO 14083 and GLEC?
GLEC supplies the factors; ISO 14083 supplies the rules for applying them. The standard defines how to allocate emissions across legs of a multimodal shipment, how to handle hub and transshipment emissions, how to treat empty running and which data quality tiers count as compliant. The framework provides the emission factors for road, sea, rail and air aligned with that standard, currently at version 3.2 with a further version in draft. In practice you use both, and quoting only one in a contract or tender response is incomplete.
Why do two carriers report different figures for the same load?
Because of how each number was calculated rather than how each truck performed. Emissions can rest on primary data — actual fuel burned — on modelled data using real distance with default factors, or on default industry averages, and the resulting figures differ materially. This is also why default-factor calculations cannot be used to compare carriers against each other: if a carrier reports an actual figure for your freight, it will differ from the planned estimate, and neither is wrong.
Which two variables move the number most?
Load factor and empty running. They are the two adjustments that drive the largest calculation deltas, which means effort spent refining anything else while these remain assumptions is misdirected. Capture actual load factors on your highest-volume lanes first, and treat empty return legs according to the standard rather than excluding them. As a bonus, both are also reduction levers — improving load factor and filling return legs cuts the emissions and the freight cost together.
Do we need to include hub emissions?
Yes. Hub operations — loading, cross-docking and transshipment — get their own category under the standard, and handling them properly is one of the framework's most distinctive contributions. They are also among the most commonly omitted elements in a home-built calculation, which systematically understates multimodal chains. Itemise them separately from transport legs so the chain reconciles element by element rather than only at the total.
What does an auditor actually want to see?
Enough to reproduce your number independently: activity quantities and distance convention per leg, mode and vehicle configuration, the data tier and source for each leg with fallbacks shown, the factor set version and global warming potential basis, how load factor and empty running were treated, and hub emissions itemised. Capture it as the shipments move rather than reconstructing twelve months of movements later — a filing built on traceable primary data is a very different conversation from one assembled retrospectively.
Where should we start?
With your highest-volume inbound lanes, captured at element level, on whatever tier of data you can actually get today. Perfect coverage is not the goal in year one; a documented tier mix is. Get the structure right on the lanes that dominate your total, record the method alongside the number, and extend outward from there. Book a working session with one quarter of shipment data and we'll build the element-level structure with you before your next reporting cycle starts.
Report the Method, Not Just the Number
Activity captured as shipments move, primary data on the lanes that dominate the total, load factor and empty running measured rather than assumed, hubs itemised, and every calculation stamped with the factor version that produced it.
Standards and factor sets are revised regularly — confirm the current versions and your own reporting obligations before filing. General information, not assurance advice.
August 21, 2026
By Alex Rowan
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