Biomethane sites are required to have performance evaluations to demonstrate compliance with the OFGEM letter of approval/direction for a CV-directed offtake.
In the UK, the network operator requires that instruments are evaluated periodically to demonstrate they are able to meet the specifications of the Network Entry Agreement (NEA) and the Gas Safety (Management) Regulations, GS(M)R.

Performance evaluations for biomethane

Performance evaluations for custody transfer, emissions monitoring, network entry.

Biogas / biomethane plant in a maize field - performance evaluations and inspections
ME2 Flow Metering Validation

Metering system validations of secondary instrumentation for measurement of gas volume.