Road Freight Emissions — GLEC Framework Methodology and Calculation Approach
Road freight is the largest single source of logistics emissions for most companies, and the hardest to pin down — the same shipment can carry three different carbon numbers depending on which boundary, which region, and which truck class you choose.
The GLEC Framework exists to make that one number, comparable across every carrier and every border.
GLEC road-freight emissions are tonne-kilometres × a well-to-wheel intensity (kg CO₂e/t-km) selected by region, truck class, and fuel. The result reports under GHG Protocol Scope 3 Category 4 on an AR6 GWP-100 basis.
The reference methodology for calculating road-freight carbon under the Smart Freight Centre’s GLEC Framework v3.2: how a tonne-kilometre is built, how the region / truck-class / fuel intensity row is selected, why the framework reports well-to-wheel by default, the empty-running and load-factor treatment that separates a defensible figure from a misleading one, and the data-quality hierarchy verifiers will check. Intensity factors are read live from the GreenCalculus MasterBrain; worked examples are hardcoded for audit reconciliation.
This page documents the road mode of the GLEC Framework v3.2 — the logistics-emissions accounting method maintained by the Smart Freight Centre and the operational backbone of ISO 14083‘s transport-chain conformance. It produces a single well-to-wheel intensity in kg CO₂e per tonne-kilometre, reported under GHG Protocol Scope 3 Category 4 (upstream transport & distribution). The sea and air modes — plus rail and inland waterway — share the same skeleton but use different intensity sets and are documented separately.
A methodology page is the execution layer: it turns the standard into a calculation you can run and a verifier can reproduce. Jump to the intensity factor tables, the worked examples, or the error traps.
GLEC Framework v3.2 and Its ISO 14083 Backbone
The Global Logistics Emissions Council (GLEC) Framework is the harmonised method for calculating and reporting greenhouse-gas emissions across multi-modal logistics supply chains. It is maintained by the Smart Freight Centre and is the method that operationalises ISO 14083, the international standard for quantifying transport-chain emissions. Where ISO 14083 sets the principles, the GLEC Framework supplies the default intensity factors, modal segmentation, and allocation rules a practitioner actually applies.
Road freight is the most data-rich mode in the framework. The GreenCalculus MasterBrain holds 125 GLEC v3.2 road rows segmented across four region sets — Europe & South America, North America, China, and India — each carrying a well-to-wheel intensity in kg CO₂e per tonne-kilometre on an AR6 GWP-100 basis. Every road figure on this page is read live from those rows.
A common procurement question is whether to “use GLEC or ISO 14083”. They are layers of the same stack: ISO 14083 is the conformance standard; the GLEC Framework is the implementation guidance and default-factor library that lets you conform to it. A GLEC-compliant road-freight calculation is, by construction, an ISO 14083-conformant one. Reporting under GHG Protocol Scope 3 Category 4 then consumes that result.
When to Use This Methodology
- You move goods by road through a carrier or your own fleet and need a Scope 3 Category 4 figure
- You want a number comparable across carriers, countries, and modes
- You have tonne-kilometre activity data, or fuel/distance data you can convert to it
- You are reporting to CDP, SBTi, or a customer that expects ISO 14083-conformant logistics figures
- The vehicles are your own and you hold fuel records — that is Scope 1 mobile combustion, not Cat 4 (see the DEFRA delivery-vehicle basis)
- You need last-mile parcel or cold-chain treatment — those carry mode-specific refinements documented separately
- The freight is sea, air, rail, or inland waterway — use the matching GLEC modal methodology
- You are quantifying upstream fuel production only — that is well-to-tank, a component, not the whole figure
- You are the seller arranging carriage of sold goods onward to customers or retailers — that is downstream transportation & distribution (Scope 3 Category 9), not upstream Category 4
Step 1 — Activity Data: The Tonne-Kilometre
Every GLEC road figure rests on one activity unit: the tonne-kilometre (t-km) — one tonne of goods moved one kilometre. The intensity factors are expressed per t-km, so the calculation is deliberately simple at its core:
Emissions (kg CO₂e) = transport activity (t-km) × intensity factor (kg CO₂e / t-km). Everything difficult about GLEC road freight is in building the t-km correctly and selecting the right intensity row — not in the multiplication.
Mass × distance — and which distance counts
Transport activity is chargeable mass multiplied by distance travelled. Mass is the actual goods weight (including packaging carried as part of the consignment). Distance is where most errors enter, because three conventions exist and they do not return the same number:
| Distance convention | What it measures | When GLEC accepts it |
|---|---|---|
| Actual distance | Real road kilometres driven for the consignment, from telematics or routing data | Preferred — highest data quality where available |
| Shortest feasible distance (SFD) | Realistic road network distance between origin and destination | Accepted default when actual distance is unavailable |
| Great-circle distance (GCD) | Straight-line distance between two points | Not appropriate for road on its own — it understates real road distance and is used only with a documented road correction |
Where tonne-kilometres come from
In order of decreasing data quality: primary carrier data (the carrier reports actual t-km and fuel), modelled t-km from shipment weight and a routed distance, and — as a last resort — an estimate from spend or average payloads. The data-quality tier you land in is recorded and affects how a verifier weights the figure (see Step 7). If you only hold fuel and distance, GLEC lets you work from fuel consumption directly rather than t-km, which is the most accurate route of all because it removes load-factor assumptions.
Step 2 — Selecting the Right Intensity Row
The intensity factor is not a single number — it is selected along three axes. Picking the wrong row is the most common and most material error in road-freight accounting, because intensities span more than an order of magnitude between a loaded long-haul artic and a small diesel van.
freight_detailed.road.<region>
<region>.<class>
<class>.<fuel>
The GLEC road factor set groups Europe and South America together because their representative road fleets and fuel specifications are close enough to share one default intensity table. This is a deliberate framework grouping, not a data error. If a journey is wholly within one of those regions, the shared factor still applies; do not “correct” it to a Europe-only or South-America-only row, because none exists.
Step 3 — The Well-to-Wheel vs Tank-to-Wheel Boundary
GLEC reports well-to-wheel (WTW) by default, and this is the single most important boundary decision in the method. WTW is the sum of two components:
Well-to-wheel = well-to-tank + tank-to-wheel
The headline GLEC intensity is always the WTW figure. It decomposes into an upstream fuel-production component (WTT) and a combustion component (TTW). The factor tables below render the WTW figure live; the WTT/TTW split is taken from the GLEC source citation and shown in the worked examples.
Well-to-tank
Extraction, refining, and distribution of the fuel before it reaches the vehicle tank. For battery-electric freight this is where the grid-generation emissions sit. Maps to well-to-tank in the glossary.
Tank-to-wheel
Emissions from burning the fuel in the engine — the tailpipe figure. This is the boundary a DEFRA-style Scope 1 fleet calculation reports on its own, which is why the two methods rarely match.
Well-to-wheel
WTT + TTW. The GLEC default and the figure that belongs in a Scope 3 Category 4 inventory, because Cat 4 accounts for the full upstream transport footprint, not just combustion.
For a battery-electric road vehicle the tank-to-wheel figure is zero — there is no tailpipe combustion — so the entire well-to-wheel intensity sits in the well-to-tank component, representing grid-generation emissions. This is the opposite shape from diesel, where TTW dominates. It is the clearest illustration of why reporting tank-to-wheel alone would flatter an electric fleet to zero while penalising none of its real grid footprint. Always report WTW.
If you are reconciling a GLEC figure against a tank-to-wheel-only fleet calculation built on DEFRA delivery-vehicle factors, expect the GLEC number to be higher — it includes the upstream fuel-production term the tailpipe figure omits. The two are not inconsistent; they report different boundaries.
Step 4 — Emission Intensity Factors (kg CO₂e per tonne-km)
The tables below render the live GLEC v3.2 well-to-wheel intensities from the MasterBrain. Each value updates automatically when the underlying GLEC data version bumps. All figures are kg CO₂e per tonne-kilometre on an AR6 GWP-100 basis, reporting under Scope 3 Category 4.
Europe & South America — summary defaults by truck class
| Truck class | Weight band | WTW intensity WTW | Unit |
|---|---|---|---|
| Van | < 3.5 t | 0.840 | kg CO₂e/t-km |
| Urban truck | 3.5–7.5 t | 0.335 | kg CO₂e/t-km |
| Medium goods vehicle | 7.5–20 t | 0.210 | kg CO₂e/t-km |
| Heavy goods vehicle | > 20 t | 0.125 | kg CO₂e/t-km |
Per-tonne-kilometre intensity falls sharply as vehicle size rises, because a larger truck spreads its fuel burn across far more payload. A heavy articulated lorry can be an order of magnitude more carbon-efficient per tonne-km than a small van carrying the same goods. This is why consolidating freight onto fewer, fuller, larger vehicles is the highest-leverage operational decarbonisation lever — and why the load factor (Step 6) matters as much as the vehicle choice.
Detailed rows — Europe & South America and North America
These are the specific rows used in the worked examples below. The WTW column renders live; the well-to-tank and tank-to-wheel components are documented in the worked examples and are taken from the GLEC source citation, not the shortcode (the factor field exposes the WTW total only).
| Row | Region | Fuel | WTW intensity WTW |
|---|---|---|---|
| Articulated 34–40 t, average | Europe & South America | Diesel | 0.101 |
| Rigid 7.5–12 t, average | Europe & South America | Diesel | 0.223 |
| Articulated 34–40 t (SI), average | Europe & South America | LNG | 0.105 |
| Truckload (TL) dry van | North America | Diesel | 0.093 |
| Less-than-truckload (LTL) dry van | North America | Diesel | 0.218 |
| Refrigerated | North America | Diesel | 0.096 |
China carries the deepest road coverage in GLEC v3.2 (the largest set of region rows), while India is the thinnest — sufficient for headline truck classes but with less granularity. Where an India sub-class is absent, fall back to the closest documented class and record the substitution as a data-quality note rather than borrowing a row from another region.
Step 5 — Worked Examples
Two reconcilable calculations. Every input, factor, and intermediate value is hardcoded so the arithmetic still reconciles when a verifier reads it next year. The WTW intensities below match the live factor table above as of the review date; the WTT/TTW components are taken from the GLEC v3.2 source citation for each row.
Payload: 18 tonnes · Distance (shortest feasible): 600 km
Row: freight_detailed.road.eu_sa.artic_34_40t.avg.diesel WTW 0.101 = WTT 0.023 + TTW 0.078 kg CO₂e/t-km (GLEC v3.2 source cell). Intensity hardcoded here as an audit snapshot; the live table renders the same WTW value.
Payload (this consignment’s share): 4 tonnes · Distance: 1,200 km
Row: freight_detailed.road.na.ltl_dry_van.diesel WTW 0.218 = WTT 0.038 + TTW 0.180 kg CO₂e/t-km (GLEC v3.2 source cell). Compare to NA TL dry van at WTW 0.093 — the LTL row is higher because partial loads share a truck and run less efficiently per tonne.
Step 6 — Empty Running, Load Factor, and Allocation
The GLEC default intensities already embed a representative load factor and a representative share of empty running for each class — that is what makes them defaults. The edge cases below are where a practitioner either improves on the default with primary data or, more often, gets the figure wrong by double-counting or misallocating.
Load factor
The fraction of the vehicle’s capacity actually used. The GLEC default factors assume an average load; if you hold primary data showing a consistently fuller or emptier operation, GLEC permits adjusting the intensity accordingly. A lower load factor raises per-tonne-km intensity, because the same fuel moves less freight.
Empty running
Kilometres driven with no payload — the return leg of many dedicated movements. GLEC’s default intensities already allocate a representative empty-running share into the laden figure. Do not add empty kilometres a second time as separate t-km; that double-counts. Only adjust if your primary data shows empty running materially different from the class default.
Allocation across consignments
When several shippers’ goods share one vehicle (the LTL case), each consignment is allocated emissions in proportion to its t-km share — mass × distance for that consignment over the total. This is why the LTL intensity row exists: it captures the efficiency penalty of shared, partial loads so each shipper carries a fair share.
Refrigeration and ancillary load
Temperature-controlled transport burns additional fuel for the reefer unit. GLEC provides dedicated refrigerated rows (e.g. the North America refrigerated class) that embed this load. Use the refrigerated row rather than applying a generic dry-van factor and adding an ad-hoc uplift.
The most frequent material error after wrong-row selection is treating empty return kilometres as additional billable tonne-kilometres on top of a default intensity that already accounts for them. The default factor is a per-laden-t-km figure with empty running baked in. Adding empty legs again inflates the result, sometimes by 30–50%. Either use the default as-is, or switch to a fuel-based calculation that sidesteps load assumptions entirely.
Step 7 — Data Quality Hierarchy and GLEC Governance
GLEC is explicit that not all inputs are equal, and a defensible figure records where its data sits in the quality hierarchy. This is what a verifier checks first.
| Tier | Input | Example |
|---|---|---|
| 1 — Primary (highest) | Carrier-reported actual fuel and distance | Telematics fuel burn + routed distance, converted with a fuel factor |
| 2 — Modelled | Actual t-km × GLEC default intensity | Known shipment weight and distance, default region/class/fuel row |
| 3 — Estimated (lowest) | Estimated t-km from spend or average payloads | Spend on freight ÷ average rate, then default intensity |
The GLEC Framework is governed by the Smart Freight Centre, a non-profit that maintains the method, the default-factor library, and the accreditation programme for conformant tools and carriers. Because the framework operationalises ISO 14083, a calculation that follows GLEC defaults and allocation rules is positioned to meet that standard’s conformance requirements, which is increasingly what enterprise customers and disclosure frameworks ask for.
The highest-quality road-freight figure is not the most elaborate t-km model — it is a fuel-based calculation. If a carrier reports actual litres of diesel burned for your consignment, applying a fuel emission factor removes every load-factor and empty-running assumption, because real fuel already reflects real loading. Reserve the default intensity tables for when fuel data is genuinely unavailable.
GLEC vs DEFRA Delivery Vehicles vs ISO 14083 vs GHG Protocol Scope 3
| Method / standard | Role | Default boundary | Activity unit |
|---|---|---|---|
| GLEC Framework v3.2 | Logistics-emissions calculation method + default factors | Well-to-wheel | Tonne-kilometre |
| ISO 14083 | International conformance standard GLEC operationalises | Well-to-wheel | Tonne-kilometre |
| DEFRA delivery vehicles | UK factor set for own-fleet vehicles | Tank-to-wheel (combustion) | Vehicle-km or t-km |
| GHG Protocol Scope 3 | Reporting framework that consumes the result | Defines Cat 4 as upstream transport | Reports the kg CO₂e total |
The mental model: GHG Protocol tells you where the number goes (Category 4, upstream transport & distribution); ISO 14083 tells you the principles; the GLEC Framework gives you the factors and rules to compute it; and the DEFRA delivery-vehicle set is the alternative for own-fleet movements that belong in Scope 1 on a tank-to-wheel basis. A GLEC WTW figure and a DEFRA tank-to-wheel figure for the same trip will differ by the upstream fuel term — by design, not by error.
What a Calculator Handles vs What You Decide
The Road Freight Calculator automates the lookup and arithmetic. The judgement calls that determine whether the figure is defensible remain yours.
- Selecting the region / class / fuel intensity row from your inputs
- Computing t-km from weight and distance
- Multiplying t-km by the live WTW intensity
- Splitting the result into WTT and TTW components
- Converting fuel volume to emissions where fuel data is available
- Boundary: confirm WTW is what your disclosure needs (it usually is for Cat 4)
- Data quality: is your t-km primary, modelled, or estimated?
- Service type: TL vs LTL vs dedicated — it changes the row
- Load factor: accept the default, or adjust from primary data?
- Empty running: already in the default — do not add it again
- Region match: does the journey’s fleet match the GLEC region set?
GreenCalculus provides a Scope 3 Category 4 road-freight calculator that automates the steps in the left column; it reads the same GLEC v3.2 intensities documented here through the calculation engine.
Error Traps — With Consequences
| Error | What happens | Consequence | How to avoid |
|---|---|---|---|
| Reporting tank-to-wheel as the total | Using a combustion-only figure and calling it the Cat 4 number. | Understated footprint Omits the upstream fuel-production term; understates a diesel trip and zeroes an electric one entirely. |
Report well-to-wheel. GLEC’s headline intensity is already WTW. |
| Wrong truck class or service type | Applying a TL row to an LTL shipment, or an HGV row to a van. | Error > 2× either direction Intensities span more than an order of magnitude across classes; LTL is ~2.3× the TL figure. |
Match the row to the actual vehicle and service type before anything else. |
| Double-counting empty running | Adding empty return kilometres as extra t-km on a default intensity. | 30–50% inflation The default factor already embeds representative empty running. |
Use the default as-is, or switch to a fuel-based calculation. |
| Great-circle distance for road | Using straight-line distance with no road correction. | Understated distance Road distance exceeds straight-line; GCD alone understates t-km. |
Use actual or shortest-feasible road distance; correct GCD if used. |
| Mixing GWP bases in one total | Summing AR6-basis GLEC figures with AR5-basis DEFRA figures. | Inconsistent inventory GLEC road rows are AR6 GWP-100; DEFRA fuel factors carry AR5 by design. |
Keep one basis per total; do not convert or blend bases silently. |
| Forcing a region that doesn’t exist | Splitting Europe & South America, or borrowing a row across regions. | Misattributed factor eu_sa is one shared set; India lacks some sub-classes by design. |
Use the documented region set; record any sub-class substitution as a data-quality note. |
Methodology Metadata — For Reference Documentation
Intensity values render live from the GreenCalculus MasterBrain; the worked-example arithmetic and WTT/TTW component splits are hardcoded audit snapshots reconciling to the GLEC v3.2 source citation as of the last review date.
Frequently Asked Questions
The GLEC Framework is the harmonised method for calculating and reporting greenhouse-gas emissions across logistics supply chains, maintained by the Smart Freight Centre. ISO 14083 is the international standard for quantifying transport-chain emissions; the GLEC Framework is the implementation guidance and default-factor library that operationalises it. A GLEC-compliant road-freight calculation is, by construction, ISO 14083-conformant. The result then reports under GHG Protocol Scope 3 Category 4.
Emissions equal transport activity in tonne-kilometres multiplied by an intensity factor in kg CO₂e per tonne-kilometre. The tonne-kilometre is chargeable mass times distance travelled, and the intensity is selected by region, truck class, and fuel. GLEC reports the well-to-wheel intensity by default, which is the figure that belongs in a Scope 3 Category 4 inventory.
Tank-to-wheel (TTW) is the combustion emissions from burning fuel in the engine — the tailpipe figure. Well-to-tank (WTT) is the upstream emissions from extracting, refining, and distributing the fuel. Well-to-wheel (WTW) is the sum of the two and is the GLEC default. A tank-to-wheel-only calculation, such as a DEFRA-style own-fleet figure, omits the upstream fuel term, so it reports a lower number for the same trip. For battery-electric freight, tank-to-wheel is zero and the entire footprint sits in well-to-tank as grid-generation emissions.
GLEC groups Europe and South America into one road factor set because their representative road fleets and fuel specifications are similar enough to share a default intensity table. It is a deliberate framework grouping, not a data error. A journey wholly within either region still uses the shared factor — there is no Europe-only or South-America-only road row to switch to.
Emissions from freight moved by a third-party carrier report under Scope 3 Category 4, upstream transport and distribution. If you move the goods in your own fleet and hold the fuel records, the combustion belongs in Scope 1 mobile combustion instead, typically calculated on a tank-to-wheel basis with DEFRA delivery-vehicle factors. The GLEC figure on this page is the Category 4 case.
Not on top of a default intensity. The GLEC default factors already allocate a representative share of empty running into the per-laden-tonne-kilometre figure. Adding empty legs again as separate tonne-kilometres double-counts and can inflate the result by 30–50%. Only adjust if you hold primary data showing empty running materially different from the class default — or switch to a fuel-based calculation, which removes load and empty-running assumptions entirely.
The GLEC v3.2 road intensities are stated on an AR6 GWP-100 basis, consistent with current corporate GHG-reporting defaults. Note that DEFRA-sourced fuel and UK grid factors carry an AR5 basis by design — do not blend AR5-basis and AR6-basis figures inside one inventory total. Keep one basis per total.