Guidance

Heat Network Technical Assurance Scheme (HNTAS)

Updated 30 April 2025

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This publication is available at https://www.gov.uk/government/publications/heat-networks-regulation-technical-standards/heat-network-technical-assurance-scheme-hntas

The Energy Act 2023 provides the powers for government to mandate heat network technical standards in Great Britain through regulations. We are introducing regulatory technical requirements and a Heat Network Technical Assurance Scheme (HNTAS) to help heat network operators demonstrate compliance with these requirements. HNTAS is due to launch in 2026 and aims to ensure that heat networks meet a minimum level of performance and reliability.

1. Overview of HNTAS

Since the end of 2022 DESNZ has been working with its Technical Author (Fairheat) to develop a technical standards Code. This sets out technical requirements (e.g. pipe insulation, water flow temperatures) which will be mandated in upcoming regulation. Many of these technical requirements build on the voluntary standards set out in CIBSE CP1 (2020). DESNZ and Fairheat have also been developing a scheme of assessment and certification to ensure heat network compliance with these technical requirements can be demonstrated. Together, these requirements and assurance processes form the Heat Network Technical Assurance Scheme (HNTAS).

Technical standards regulation will apply to heat networks from communal to city wide district systems, including both new build and existing legacy networks.

2. Objectives and principles

HNTAS is being designed with deliverability and proportionality as two of its leading principles. Specifically, we are keen to ensure that the introduction of HNTAS does not place undue burden or cost on heat network operators or heat network consumers.

HNTAS will enhance the transparency of heat network performance, and strengthen accountability for parties engaged in the planning, construction, management, and maintenance of heat networks. As a result, HNTAS has the potential to reduce carbon emissions by making heat networks more efficient, reduce capital and operational costs, and improve consumer experience. 

Scheme objectives and core principles

Vision

Enable low-emissions, reliable and affordable heat to be delivered to UK communities via heat networks.

Aim

Develop a heat network technical assurance scheme that ensures a minimum level of performance and reliability for heat networks in the UK.

Objectives

  • Reduce carbon emissions and cost of heat by making heat networks more efficient
  • Improve affordability by reducing capital and operational costs
  • Improve consumer experience with improved reliability and quality of heat supplied
  • Improve reputation and investor confidence in heat networks
  • Build evidence through better data collection and reporting on technical quality

Core principles

  • Outcomes orientated
  • Preventative
  • Proportionate
  • Deliverable
  • Adaptable
  • Enforceable

HNTAS will be a performance-based assurance scheme which applies to different identifiable elements (such as energy centre, district distribution network, communal distribution network) of a heat network. For each element, assessments against minimum standards are made in various lifecycle stages of a heat network. In the design and construction stages, assessments will be made to validate the claims that certain performance outcomes will be achieved. Upon commissioning, assessments will verify that performance outcomes have been achieved and maintained.

3. How compliance will be demonstrated

Under HNTAS, heat networks will be required to pass assessments to demonstrate that they have achieved the mandated minimum technical standards.

3.1 New networks

For new networks an assessment pass will be required at 3 key points in a heat network’s lifecycle:

  • before a network is allowed to start design
  • before starting construction
  • before starting operation

An assessment pass will also be required after 2 years of operation to ensure that performance levels continue to meet requirements.

3.2 Existing networks

For existing networks, assessments will be required after a set period to ensure performance levels meet requirements. The existing stock of communal and district heat networks will also have a significant transition period to get the right metering in place, to be able to prove performance. Final performance thresholds will be set at a more permissive level for existing networks and these networks will be given time to reach these.

3.3 After achieving HNTAS certification

For both new and existing networks, assessment passes will enable a network to be awarded a HNTAS certificate as evidence of compliance with HNTAS.

Once a network achieves HNTAS certification, the heat network operator will be required to regularly submit data to a HNTAS digital portal to show they continue to meet HNTAS key performance indicators.

4. Governance structure

As provided by the Energy Act 2023, Ofgem will be the regulator of heat networks. The Energy Act provides for Ofgem to award a licence to a technical standards Code Manager. It is expected that this Code Manager will maintain the Code documents which will include the:

1. Technical specifications (what heat networks must comply with)
2. Assurance procedures (how compliance is demonstrated)
3. Assessor requirements (who can assess compliance)

The Code Manager may outsource the day-to-day operation of HNTAS to a Scheme Operator.

It is expected that registered assessors will be licensed by the Code Manager to carry out HNTAS assessments. We anticipate that certifiers also need to be licensed by the Code Manager to deliver certification activities.

5. Stakeholder engagement and consultation

Stakeholder engagement has been key in developing HNTAS. Multiple technical workshops have been held to gather ideas and expertise from manufacturers, housing associations, local authorities, consultancies, developers, contractors, energy service companies, trade associations, and professional bodies. 

The outputs of these workshops are being used to inform the Code documents, outlining the regulatory technical requirements of the scheme and how compliance can be demonstrated.  

The first draft of these documents, which includes the scheme’s technical assessment and certification requirements, will be completed shortly. We will be consulting on the HNTAS proposals and publishing the Code documents in some form in 2025. 

6. CIBSE CP1: Heat networks: Code of Practice for the UK

CP1 (2020), published by the Chartered Institution of Building Services Engineers (CIBSE), is the recognised Code of Practice for heat networks in the UK. It contains technical guidance and sets out voluntary minimum standards for UK heat networks. Having most recently been updated in 2020, CP1 will be the basis for the minimum regulatory standards used within HNTAS.

CP1 (2020) will not be an exact representation of HNTAS standards, but it does give a very good starting point in that CP1 (2020) compliant networks will be very well prepared for forthcoming regulatory technical standards. Until recently it has only been free to CIBSE members, but a partnership between CIBSE and DESNZ has now removed the paywall to make CP1 (2020) free-to-all:

7. HNTAS pilot programme

We are undertaking a pilot programme to test the technical requirements and assurance processes on real networks to make sure they work in practice.

The first wave of the programme, which includes eleven new build pilots, is underway. We’ve appointed four Assessor Organisations to evaluate these projects and have trained both Assessor Organisations and duty holders. The pilot projects span various heat network types and stages to gather comprehensive insights. Our aim is to begin piloting HNTAS on existing networks from Spring 2025. The lessons learned will help ensure HNTAS works in practice and aligns with industry needs.

8. Shadow Training Provider

Building Engineering Services Association (BESA), has been appointed as the HNTAS Shadow Training Provider.

Stakeholders have regularly raised the importance of setting up and delivering high quality training courses to prepare the market for regulation. We anticipate that HNTAS will introduce several new roles and create new job opportunities for the sector. The Shadow Training Provider will develop and deliver training courses, many of which will need to be attended by organisations and individuals before they will be able to fulfil these roles. The Training Provider is ‘shadow’ as they will be active before HNTAS launches.

The courses delivered will work towards achieving accreditation, which will ensure delegates receive high quality training and can perform key HNTAS roles to a high standard. The training courses are expected to be delivered later in 2025.

9. Next steps

  • Winter 2024 to Autumn 2025 - HNTAS pilot programme
  • Spring 2025 – first draft of Code documents completed
  • First half of 2025 - technical standards consultation
  • Within 2026 - HNTAS launches

10. News updates and reference materials

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