If a facility is used simultaneously by multiple production processes, how do you attribute the emissions from that facility to each production process?
All inputs, outputs and corresponding emissions in an installation should be attributed to a production process, unless they relate to any non-CBAM good.
Overall, the relevant emissions of an installation should be 100% covered by production processes for CBAM goods and any non-CBAM goods, where applicable.
For an installation with several relevant production processes, where shared equipment, shared ‘source streams’ or shared emission sources are relevant, inputs, outputs and emissions should be attributed to the different production processes with an appropriate share. For example, if an installation produces purified water and 60% of that water is used to produce a CBAM good, then 60% of the direct and indirect emissions related to the water purification should be attributed to the production of the CBAM good.
Source: EC’s Questions and Answers on CBAM