One boiler and one furnace serve our CBAM product and our other products. How do we split the emissions?
Attribute them to the production processes using the rules in Annex III of Implementing Regulation (EU) 2025/2547. All of the installation's emissions must land in some process, CBAM or not, with no gap and no double count. For steam, the Commission's guidance attributes boiler emissions by the heat each process consumes.
The 100% test
The Commission's Q&A says an installation's relevant emissions should be covered 100% by production processes, for CBAM goods and for any non-CBAM goods. Shared equipment, shared fuel streams and shared emission sources are split between the processes with an appropriate share. Annex III sets the attribution rules.
A shared boiler or steam network
The Commission's guidance on calculating embedded emissions says boilers, combined heat and power units and steam pipe networks used by several processes must be monitored on their own. Their emissions are then attributed according to the amount of heat each production process consumes.
What a verifier checks
- Every good is attributed to a production process without gaps or double counting.
- No non-CBAM good has crept into the boundary of a CBAM process.
- A good added during the year went into a suitable process.
What to keep
- A site diagram marking each shared unit.
- Heat or steam meter readings for each consuming process.
- The working that shows the shares add up to the installation total.
Checking the split adds up (round numbers)
- Installation total from fuel and power records: 10,000 tCO2e.
- CBAM process A: 6,500. CBAM process B: 2,800. Non-CBAM products: 700.
- 6,500 plus 2,800 plus 700 = 10,000, so 100% is covered.
If the three shares add to less or more than the installation total, a verifier will ask why.
What Senseible does here
Senseible reads your fuel, power and steam bills into verified emission records, so the monthly figures a monitoring plan needs are ready to hand to your verifier. Verified here means rule checks passed against the evidence. It is not third-party assurance, and a CBAM verifier still signs the report.
Sources: European Commission, CBAM Questions and Answers (definitive period), European Commission, CBAM Guidance No. 3, calculation of embedded emissions
Last reviewed 2026-11-04.