Guidance

HNTAS: Existing heat networks - draft technical specifications for Milestone 2

Draft Heat Network Technical Assurance Scheme (HNTAS) regulatory technical requirements to help heat network operators demonstrate compliance.

Applies to England, Scotland and Wales

Documents

Details

These draft technical specifications for existing heat networks detail the requirements and technical obligations to be fulfilled at Milestone 2 as part of the upcoming Heat Network Technical Assurance Scheme (HNTAS).

Milestone 2 relates to minimum performance and reliability thresholds, including metering and monitoring requirements.

The specifications cover the:

  • technical requirements to be met 
  • performance monitoring requirements to be met 
  • key failures to be avoided
  • evidence requirements to be provided to demonstrate conformity with HNTAS

They are for use by:

  • heat network operators
  • organisations within the heat network supply chain

These technical specifications correspond to the draft HNTAS assessment procedures for Milestone 2.

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 will launch shortly.

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

Updates to this page

Published 5 January 2026

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