A word on… TS1 and the future of heat network assurance
Steve McConnell, Director, Manufacturers of Equipment for Heat Networks Association (MEHNA), explains why the publication of Technical Standard TS1 marks a defining moment for the UK heat network sector.
For the first time, we have a national framework that will move heat networks from voluntary ‘best practice’ to mandatory, independently assured performance. This is the first part of the government’s Heat Network Technical Assurance Scheme (HNTAS), and it signals the most significant regulatory change our sector has ever faced.
Heat networks have long been criticised for inconsistent performance, with end users experiencing high costs or unreliable heating due to shortcomings in design, commissioning, or operation. Until now, there has been no formal mechanism to verify whether a system is performing as intended. TS1 begins to close that gap.
The overarching objective is one we can all support: ensuring that heat networks are designed, installed, and operated properly, so they deliver reliable, efficient heating throughout their life. With the detail now emerging, building owners, operators, and the supply chain must start to understand what is expected of them and the implications of the legislation that will follow.
Why TS1 matters
TS1 establishes a baseline for how heat networks must be specified, installed, and maintained. It is the first in a suite of standards that will underpin HNTAS and provide the reference point against which third-party assessments will be made.
Crucially, this does not only apply to new projects. Once HNTAS is in force, all heat networks will require certification. New schemes will need to comply immediately, while existing networks will be given a longer transition period. However, that is not a reason to wait. Operators should be preparing now, reviewing performance, and identifying gaps against the new requirements.
What the standard covers
TS1 is a comprehensive document because heat networks are complex systems with many interdependent parts. It addresses the full system, from plant room to consumer interface, including:
- System design principles
- Plant room configuration
- Pipework, hydraulics, insulation, and controls
- Network temperatures and efficiency
- Hydronic balance and commissioning
- Ongoing operational performance
- Consumer interfaces and metering
The message is clear: every element must be planned, delivered, and managed to a consistent, defined level. TS1 is only the first release, with further standards to follow. The Department for Energy Security and Net Zero (DESNZ) is taking a long-term, structured approach, and industry will need to keep pace.
HIU certification: A key requirement
Heat interface units (HIUs) are the critical link between the network and the end user. TS1 references the need for product testing and certification through an ‘acceptable accredited route’. In practice, this currently means compliance with the BESA HIU test standard, which is the recognised benchmark in the UK. Manufacturers, developers, and operators will therefore need to ensure they are working with certified equipment. The test assesses domestic hot water performance, space heating efficiency, heat loss, control behaviour, responsiveness, metering, and system integration.
As HNTAS is phased in, this moves from best practice to mandatory compliance, with assessors looking for HIUs labelled as tested to the BESA 3.0 or 3.1 standard.
A shift for owners and operators
Perhaps the greatest change will be felt by those responsible for running heat networks. For the first time, there will be independent assurance of performance, with third-party certification required not only at completion, but throughout the system’s operational life. This not only creates accountability, it also creates opportunity. Well-designed, well-managed networks will have the evidence to prove it, helping to restore trust among end users, building owners, and local authorities.
There will, of course, be challenges. Retrofitting older systems to meet new requirements will take time, investment, and expertise. We must ensure standards raise performance without discouraging development. Heat networks remain essential to decarbonising heat in dense urban environments, and that balance will be critical.
Preparing for what comes next
Although the original HNTAS start date has been delayed while government reviews timings, the technical direction is now clear. Delay in legislation should not mean delay in preparation. Working closely with its members and the wider industry, MEHNA has launched a new guidance document, Installation, Commissioning and Maintenance of Heat Interface Units for the Heat Network Technical Assurance Scheme, to support installers, commissioners, and service engineers working with HIUs. MEHNA will continue to share information, support compliance, and feed practical insights back to policymakers.
TS1 is an industry milestone. If implemented correctly, it will strengthen confidence, improve outcomes for consumers, and help secure the future of heat networks as a cornerstone of the UK’s Net Zero journey.
