How to Calculate CO2 Per Move for Corporate Clients

Why a client is asking

The buying organisation has to account for emissions from transport it purchases. That sits in Scope 3, Category 4, upstream transportation and distribution, under the GHG Protocol.

The pressure comes from several directions at once. Streamlined Energy and Carbon Reporting has been mandatory since 2019 for large companies. TCFD-aligned disclosure became mandatory in April 2022 for over 1,300 of the largest UK companies and financial institutions. UK Sustainability Reporting Standards were published in February 2026 and are currently voluntary, with the FCA consulting on mandatory application to listed companies for financial years beginning on or after 1 January 2027. EU CSRD reaches UK businesses through EU parent companies and through value-chain data requests.

In the public sector it is more concrete. Under PPN 006, a published Carbon Reduction Plan covering Scope 1, Scope 2 and defined Scope 3 categories including upstream transportation is a condition of participation for contracts above five million pounds a year. NHS procurement has required one across all procurement since April 2024.

So the request is not an environmental gesture. It is a reporting obligation being passed down the supply chain.

The method

Step one: establish fuel consumed

The strongest basis is actual fuel. Litres, by vehicle, by date, from fuel card records or fuel management data.

This matters because measured data is materially more defensible than modelled data, and a sophisticated buyer will ask which you are using.

Where actual fuel is unavailable, distance travelled multiplied by a vehicle-class consumption factor produces a modelled figure. This is accepted practice but should be labelled as modelled rather than measured.

Step two: convert to emissions

Apply the published UK government greenhouse gas conversion factors, updated annually, to convert litres of fuel into kilograms of CO2 equivalent.

ISO 14083 uses well-to-wheel accounting, which includes the emissions from producing and distributing the fuel as well as burning it. This produces a higher and more complete figure than tank-to-wheel accounting.

Step three: allocate to the job

This is the difficult part, and it is where most attempts fall down.

A vehicle carrying four jobs in a day consumed fuel once. Attributing the right share to each job requires an allocation basis, normally weight or volume share multiplied by the distance each consignment travelled.

ISO 14083 also requires accounting for empty running and partial loading, because a half-empty vehicle emits nearly as much as a full one and the emissions have to go somewhere.

Allocation is only possible if you know what was on the vehicle, how much it weighed or measured, and what route it took. Without an operational record containing all three, per-job allocation is guesswork.

The standards

ISO 14083:2023, published 20 March 2023, is the international standard for quantifying and reporting greenhouse gas emissions from transport chain operations. It distinguishes transport operations from hub operations and specifies well-to-wheel accounting.

The GLEC Framework, maintained by Smart Freight Centre, is the primary industry implementation guideline and is aligned with ISO 14083. The current version is 3.2, released in October 2025, which added a module covering air pollutant emissions.

Conformance is expressed through the levels defined in ISO 14083, described as declared, verified and third-party assured. These are operationalised through Smart Freight Centre's Conformity Assessment Scheme, which also certifies tools and programmes and maintains a register of validation and verification bodies.

In the EU, the CountEmissions initiative sets EN ISO 14083:2023 as the reference methodology, which will consolidate its position further.

What to give the client

Three things, in ascending order of usefulness.

A figure. Kilograms of CO2 equivalent for the move.

The basis. Whether it is derived from measured fuel or modelled from distance, what conversion factors were used and from which year, and what allocation method was applied.

A method statement. A short document setting out the approach, referencing ISO 14083, which the client's sustainability team or auditor can review.

The third is what makes the first two credible. A number without a method is not usable in a reporting context, because the client cannot defend it.

Claims to avoid

Do not describe a figure as certified unless it has been through a conformance assessment. Conformance to a methodology is not the same as certification against it, and the distinction matters to the people receiving the data.

Do not present modelled figures as measured.

Do not claim uniqueness. The methodology is public and the conversion factors are free.

The defensible position is that the calculation is built to the ISO 14083 method with the workings available. That is both accurate and sufficient for most procurement purposes.

Why most suppliers cannot do this

Not because the maths is difficult. The conversion is arithmetic and the factors are published.

The obstacle is allocation. Producing a per-move figure requires knowing what was on the vehicle, what it weighed or measured, where it went and what fuel was consumed, all joined together. Most operators hold those four things in four different places, if they hold them at all.

Which is why the request from a corporate client frequently receives either no answer or a figure with no method behind it. This is one of four emerging requirements in corporate relocation tendering.

Frequently asked questions

How do you calculate CO2 for a removals job?

Take the fuel consumed, convert it to CO2 equivalent using the published UK government conversion factors, then allocate the result across the jobs the vehicle carried, normally by weight or volume share against distance. ISO 14083 is the recognised methodology.

What is ISO 14083?

The international standard for quantifying and reporting greenhouse gas emissions arising from transport chain operations, published in March 2023. It uses well-to-wheel accounting and requires empty running and partial loading to be accounted for.

What is Scope 3 Category 4?

Upstream transportation and distribution in greenhouse gas accounting. Transport services a company purchases, including relocation and removals, fall into this category in the buying organisation's emissions reporting.

Do removals companies need to report carbon emissions?

Not directly, unless they are large enough to fall within SECR. The requirement arrives contractually, through corporate clients who need the data for their own Scope 3 reporting and through public contracts requiring a Carbon Reduction Plan.

Is modelled emissions data acceptable?

Generally yes, provided it is labelled as modelled rather than measured. Actual fuel data is materially stronger and a sophisticated buyer will ask which basis was used, so the distinction should be stated rather than obscured.

Sources and further reading

• ISO 14083:2023, greenhouse gas emissions of transport chain operations
• GLEC Framework version 3.2, Smart Freight Centre, October 2025
• UK government greenhouse gas conversion factors, published annually
• GHG Protocol Corporate Value Chain (Scope 3) Standard, Category 4
• Cabinet Office PPN 006, Carbon Reduction Plans and its Technical Standard
• Department for Business and Trade, UK Sustainability Reporting Standards S1 and S2, February 2026

Position current as at July 2026. Conversion factors are updated annually and the current year's figures should always be used.