HNTAS: Existing heat networks - draft assessment procedures for Milestone 4

These draft assessment procedures for existing heat networks detail the activities to be undertaken to verify compliance with Milestone 4 requirements in the upcoming Heat Network Technical Assurance Scheme (HNTAS).  They cover the requirements to achieve HNTAS Certification 1.

The documents are for use by:

• heat network assessors
• heat network operators

These assessment procedures correspond to the draft the HNTAS technical: Existing heat networks - draft technical specifications for Milestone 4.

Next steps

We will be requesting feedback on the information in these documents. We will run a change management process in parallel with the HNTAS technical standards consultation which willcloses launchon shortly.15 April 2026.

We will make final versions of these documents available before the scheme starts.