The Heat Network Technical Assurance Scheme (HNTAS) will mandate minimum technical requirements for new and existing heat networks. This article provides an overview of the proposed scheme and how developers, landlords, and heat network operators can prepare.
The Department for Energy Security and Net Zero (DESNZ) intend to introduce minimum technical requirements for new build and existing heat networks. These standards will apply to all networks – from small communal heat networks to city-wide district heat networks.
What is HNTAS?
The Heat Network Technical Assurance Scheme (HNTAS) is the new compliance framework for technical standards. A technical standards Code will contain minimum requirements (such as water flow temperatures), and an assessment and certification scheme will set out how compliance with these requirements can be demonstrated.
The aim is to ensure a minimum level of performance and reliability for heat networks in the UK, alongside reducing carbon emissions, improving affordability and consumer experience, and building evidence through better data collection and reporting.
What standards will apply?
Technical Standards will be specified for each phase of design, construction and operation, and each heat network element (e.g. energy centre, distribution networks, substations and consumer systems). These Technical Standards are expected to cover:
- Technical requirements
- Performance monitoring requirements
- Key failures to be avoided
- Evidence requirements to demonstrate compliance
An impartial assessment and independent certification will be required to ensure that Technical Standards have been met and that key performance indicators (KPIs) will be (or have been) achieved.
Following certification, data must be submitted on a regular basis to demonstrate that key performance indicators continue to be met.
Technical specifications and assessment procedures
On 30 July 2025, DESNZ published draft technical specifications (that set out the Technical Standards that heat networks must comply with) and draft assessment procedures (that set out how compliance is demonstrated).
Further technical specifications and assessment procedures for new build networks and existing networks are expected to be published during Autumn – Winter 2025.
It is expected that technical standards will build on CP1 (2020) voluntary requirements, which provides a good starting point for compliance. CP1 (2020) is the recognised Code of Practice for heat networks in the UK, published by the Chartered Institution of Building Services Engineers (CIBSE).
New Gateways for new builds?
New heat networks will be required to demonstrate minimum technical standards have been met at three key "Gateways": design, construction and operation, a further assessment will be required after two years of operation, with ongoing monitoring to ensure that performance standards are maintained.
It has been proposed that "Duty Holders" will be responsible for achieving assessment passes and certification at each Gateway, with data requirements forming a "Golden Thread" throughout the network's lifecycle, similar to existing processes under the Building Safety Act.
With housebuilders already experiencing significant delays under the Gateways regime for Higher-Risk Buildings, it remains to be seen whether this process will add to the pressure on programmes, particularly if there is a shortage of licensed HNTAS assessors and certifiers.
Further clarity is also required on how HNTAS will apply to phased developments, including whether developments that have already started design or construction will be treated as "existing networks" from the introduction of HNTAS in 2026.
Upgrading legacy networks
All existing heat networks will be assessed after a set period of time to ensure minimum requirements are met. It is understood that HNTAS will set out a transition period for existing heat networks to submit improvements plans and install minimum levels of metering.
It is proposed that a different approach will be taken for heat networks installed prior to the introduction of the Heat Network (Metering and Billing) Regulations 2014.
From 2015 onwards, heat networks within scope of these regulations were required to meet minimum requirements around metering and monitoring. Older heat networks are likely to be granted a longer timeframe for achieving HNTAS certification.
How to prepare
The technical standards consultation is expected to be published before the end of 2025, ahead of the launch of HNTAS in 2026.
For existing networks, due diligence will be required to review the performance of existing heat network plant and equipment, including metering systems. Any existing defects and inefficiencies should be identified in advance so there is time to plan for any necessary works or upgrades.
New developments will need to factor HNTAS assessments and certifications into all stages of design, construction and operation, particularly where programme timelines may be impacted.
In order to help upskill the industry ahead of the introduction of regulation, the Building Engineering Services Association (BESA) has been appointed as the shadow training provider for HNTAS. The first HNTAS training courses are now live, including an introductory course funded under the Government's heat training grant scheme.
If you are concerned about how HNTAS or wider heat network regulation may impact your organisation, please get in touch with a member of our Energy and Sustainability team.
