Product carbon footprints for chemical suppliers

Why your chemical customers are asking

For a chemical company, purchased raw materials are often the largest source of emissions outside its own plants. They count as Category 1 of Scope 3, purchased goods and services. To report and cut them, your customer needs product figures from the suppliers who make those materials.

The TfS Product Carbon Footprint Guideline for the Chemical Industry, version 3.0, published in December 2024, sets a clear order of preference for where your customer's figure comes from:

1. 1BestThe supplier's own product footprint, calculated to the guideline.
2. 2NextAn average for that material from a recognised database.
3. 3Last resortAn estimate based on the money spent.

A database average treats every supplier of a chemical as the same. Your own footprint lets a customer credit you for lower-carbon production and track your progress year on year.

The unit and the boundary

Under the guideline, a footprint is stated per 1 kg of unpackaged product at your factory gate, whether the product is a solid, liquid or gas. If packaging is included, the unit becomes 1 kg of packaged product, still counting only the mass of the product. Currency units are not used.

The boundary is cradle-to-gate, including transport. In summary, the guideline's boundary table looks like this:

Flows that are insignificant may be left out, but must be reported as exclusions. A material with a large upstream footprint must be included however little of it you use. If in doubt, estimate it first.

Data age, energy and steam

The guideline sets limits on how old your data can be. Primary data should be as recent as practicable, normally the latest full year and never older than three years. Secondary data should be the latest available, with database inventories no older than ten years. A footprint stays valid for up to three years from the reference year of its data. Recalculate sooner if a change in the production process moves the footprint by more than 20%.

Energy is often a large part of a chemical footprint. The guideline asks you to calculate electricity using the market-based approach in the GHG Protocol Scope 2 Guidance and to say that you did. Energy emissions should include the upstream supply of fuels as well as generation, so if your supplier gives you only a combustion factor, you add the upstream part yourself.

For steam from your own boiler, count the fuel burned and its upstream supply, then share the boiler's emissions between the products that use the steam. A combined heat and power unit also needs its emissions split between heat and power, and the guideline explains how.

When one process makes several products

Reactions give co-products, distillation splits a stream, and plants export steam. The guideline, following the PACT Methodology, sets this order for dividing emissions between outputs:

1. 1Product rulesUse the method in an accepted product category rule, where one exists.
2. 2Divide the processSplit it into sub-processes to avoid allocation, if possible.
3. 3Expand the systemInclude the co-product where a clear substitute exists.
4. 4Physical relationshipAllocate by mass, energy content or the stoichiometry of the reaction.
5. 5Economic valueUse value only where no physical relationship works.

Only co-products receive a share. Waste receives none; the emissions from treating it are added to the products instead. Emissions that your product helps others avoid are never subtracted from its footprint, and carbon credits you buy do not reduce it either. Both may be reported separately.

The guideline also has specific rules for tolling and contract manufacturing, recycled content, carbon capture and mass-balanced materials. For mass balance, the link between documents and physical material must hold as ISO 22095 sets out. If any of these applies to you, read that section in full and state which rule you applied.

Data quality and a first footprint

Version 3.0 aligns data quality with the PACT Methodology. Two measures travel with your footprint: the primary data share, meaning the proportion of emissions calculated from primary data, and a data quality rating for how well each dataset matches the real process in technology, geography and time. Neither is a pass mark, and both should improve each year.

A practical order of work for your first product:

• Find out which products your customers want footprints for, by when, and to which rules.
• Choose one high-volume product made on few lines.
• Draw its process: inputs, outputs, co-products, wastes and energy.
• Collect a full year of production, raw material, energy and waste data.
• Ask your largest raw material suppliers for their own footprints.
• Calculate, share out multi-output emissions and rate the data quality.
• Keep an evidence file: product definition, bill of materials and yields, energy data with meter or invoice references, factors with name, version and year, allocation choices and exclusions.

For the general method, step by step, see our product footprint calculation guide.

How ESGen helps

Carbon per product is a service our team scopes with you, following the TfS guideline, the PACT Methodology or ISO 14067 as your customer asks. The ESGen platform holds your site electricity, gas and fuel figures with the bill and factor behind each one, which is where the energy part of a chemical footprint starts.

ESGen is not a member of or partner to TfS, and we do not verify footprints; independent verifiers do. Read more on product footprints, or book a demo and send us the request your customer sent you.