It is permissible to have combined metering for a shared on-site or district system that combines heating / cooling, and domestic hot water generation.
In all cases, justification is provided in the QA report for the combined metering, and explains why it is not technically feasible to provide separate meters.
21-Sep-2022 Applicability of KBCN added to BIU V6. Amended to include district heating and cooling networks.