Currently, the presence of smart meters are not an input into the Standard Assessment Procedure EPC calculation.
Nor will they affect the EPC calculation in the 2022 revised SAP 10.2 - but their presence
may be noted on the EPC.
See
https://bregroup.com/sap/sap10/ and follow the 'SAP 10.2 specification (21/04/2022)' link to open the PDF: 'The Government’s Standard Assessment
Procedure for Energy Rating of Dwellings'.
Section 12.3 says:
"SAP software should allow assessors to record whether a smart electricity meter is fitted. This does not affect the results of the SAP calculation but may be referenced in the EPC."Likewise for a gas smart meter (section 12.4.1)