The basic idea
Calculating the carbon footprint of moving goods comes down to one simple question: how much effort did it take to move this cargo, and how dirty was the energy used to do it?
You multiply the effort by the pollution factor, and you get a CO₂ number.
That's it at the core. The complexity comes from making it fair, consistent, and comparable across different vehicles, routes, and companies.
What you need to start
Three ingredients:
| Ingredient | What it means | Example |
|---|---|---|
| Cargo weight | How heavy are the goods? | 5 tonnes of furniture |
| Distance | How far do they travel? | 800 kilometres by road |
| Energy type | What vehicle moves them, and what fuel does it use? | A diesel HGV truck |
Step 1: Turn weight × distance into one number
Logistics uses a combined unit called a tonne-kilometre (tkm). It captures both how heavy the cargo is and how far it travels in a single figure.
Move 2 tonnes of goods for 100 km = 200 tonne-kilometres
Think of it like a taxi meter — except instead of measuring time and distance, it measures weight and distance. The heavier your cargo and the longer the trip, the higher the reading on the meter.
Step 2: Apply the "pollution factor"
Now you multiply the tonne-kilometres by an emission intensity factor — a standard number that tells you how much CO₂ a particular vehicle type produces per tonne-kilometre.
200 tkm × 0.062 kgCO₂e per tkm = 12.4 kg of CO₂
These intensity factors are published in the GLEC Framework and are different for every transport mode:
| Transport mode | Approximate intensity | Why the difference? |
|---|---|---|
| Large truck (HGV) | ~0.06–0.09 kgCO₂e/tkm | Road friction, diesel engine |
| Container ship | ~0.008–0.015 kgCO₂e/tkm | Very efficient per tonne at scale |
| Freight aircraft | ~0.5–0.8 kgCO₂e/tkm | Jet fuel, high altitude |
| Electric rail | ~0.002–0.01 kgCO₂e/tkm | Grid electricity, low friction |
A ship is roughly 5–10× more efficient than a truck per tonne-kilometre, which is why sea freight has a much lower carbon footprint per unit of cargo despite travelling much further.
Step 3: Handle multi-modal journeys
Most international shipments use several different vehicles. A factory in Germany might ship goods:
- By truck → to a port in Hamburg
- By container ship → to a port in Singapore
- By truck again → to the customer's warehouse
You don't try to calculate the whole journey at once. Instead, you break it into legs — one calculation per vehicle, per mode. Then add them all up.
| Leg | Distance | Mode | CO₂ |
|---|---|---|---|
| Hamburg factory → port | 80 km | HGV truck | 4.2 kg |
| Hamburg → Singapore | 19,300 km | Container ship | 12.6 kg |
| Singapore port → warehouse | 45 km | Light truck | 1.8 kg |
| Total | 18.6 kg |
This is exactly what ISO 14083 standardises — the rules for breaking a journey into consistent, comparable legs and calculating each one the same way, regardless of who did the calculation.
Step 4: Share emissions fairly between customers
Here's the tricky part. A truck carrying goods from a warehouse doesn't carry goods for just one company — it carries pallets for ten different customers at once.
So whose CO₂ is it?
The answer: you split it proportionally, based on weight.
Think of it like splitting a taxi fare. If five people share a cab, you don't charge the whole fare to one person. You split it based on how much space each person took up and how far they stayed in the cab.
For freight, the same principle applies:
- Your 2-tonne pallet on a 20-tonne truck = you're responsible for 10% of that truck's emissions on that leg
- If your pallet also travels twice as far as another customer's goods, you bear more of the total
This process is called allocation, and it's one of the most regulated parts of ISO 14083 — because getting it wrong means one company overpays in carbon terms while another underpays.
What "Well-to-Wheel" means
When a truck burns diesel, you see exhaust coming from the tailpipe. That's the obvious part. But before the diesel reached the engine, it had to be:
- Extracted from the ground (drilling)
- Refined into diesel
- Transported to the fuel station
- Pumped into the truck's tank
All of those steps also produce CO₂ — typically an additional 15–25% on top of what the tailpipe produces.
Well-to-Wheel means counting both parts:
Well → Tank + Tank → Wheel
(fuel production) (vehicle operation)
= FULL carbon footprintISO 14083 and the GLEC Framework require both to be included. A calculation that only counts the tailpipe is understating the true impact by roughly 20%.
Rough estimates vs. precise calculations
Not all emissions calculations are equally trustworthy. There are two approaches:
Rough estimate (default data)
Uses industry-average figures. Like guessing your monthly grocery bill based on what a typical household spends.
- Fast and cheap to produce
- Useful when you have no other data
- Tends to be conservative (higher than actual) to avoid underreporting
- May draw scrutiny under CSRD assurance review, even the lighter limited-assurance check CSRD requires, and is less likely to satisfy a shipper customer's own contractual ask for better data
Precise calculation (primary data)
Uses actual data from the specific shipment — real fuel receipts, GPS-tracked distance, verified cargo weight, measured load factors.
- Requires data from the carrier
- More work to collect
- More accurate to the actual trip
- Preferred by CSRD assurance reviewers and increasingly asked for directly by shipper customers, even though limited assurance itself doesn't strictly require it
The GLEC Framework scores data quality on a 4-tier scale. Tier 1 is the most precise (measured primary data); Tier 4 is the roughest (industry-average defaults). Companies filing CSRD disclosures are expected to improve their tier over time.
Why consistency matters more than precision alone
Two carriers could calculate emissions for the same route and arrive at numbers that differ by 75%. Both could be using legitimate methods — just different ones.
This is the problem ISO 14083 solves. By standardising:
- Which emission sources to include
- How to measure distance
- Which allocation method to use
- Whether to apply Well-to-Wheel or just tailpipe figures
…it creates a common language. When every company uses the same rules, the numbers become comparable — between carriers, between reporting periods, and between companies in a supply chain.
That comparability is what makes freight emissions data useful for CSRD reporting, procurement decisions, and external assurance.
The CO2Path approach
CO2Path applies this process at the shipment level. Each shipment is broken into legs (matching the ISO 14083 structure), each leg is calculated using the correct emission intensity factor for that mode and vehicle type, the full Well-to-Wheel figure is computed, and the result is written to a blockchain-secured record that is traceable back to the source data.
The output is not just a number — it is a verifiable, auditable record of how that number was reached.