HEAT NETWORKS


2026: The Year for HIUs?


Pete Mills, commercial technical operations manager at Bosch Commercial & Industrial, looks at the latest developments for heat interface units and what needs to happen in 2026 for heat networks to be further adopted


H


eat Interface Units (HIUs) play an important part in the performance of heat networks. A poor-performing HIU can be the make-


or-break moment for a newly developed heat network. It can cause a network to not deliver on the effi ciency levels needed or promised – and in extreme cases may need replacing. Heat networks have been around for a long time


and are regularly fl oated as one of the best ways to help decarbonise heat in multi-storey, communal and new-build domestic properties. However, the historic and continued installation of poor- performance HIUs could be an inhibitor instead of an enabler of consumer satisfaction in the future. The industry has to – and in many areas is – stepping up to the plate to restrict and remove poor performing HIUs. With new Regulations due to come into eff ect, the industry is looking to raise the bar in HIU performance and there’s more on the way. Let’s take a look at the main changes and the impact they will have on the industry.


Bring on BESA Back in 2023, trade body Building


Engineering Services Association (BESA) introduced the latest version of the HIU test regime. A mechanism that focused mainly on improving the performance of HIUs to make the journey towards a net-zero future more of a reality whilst ultimately raising the bar for higher performance from manufacturer


Left: Pete Mills, commercial technical operations manager at Bosch Commercial & Industria


www.heatingandventilating.net


products. – Although voluntary, benchmark for


HIUs thanks to its as VWART pass or


it provided a crucial specifi ers to select tough criteria such targets, clearer fail criteria and incorporating reduced return temperatures


for better network performance.


It always been a procurer led scheme, with the aim of improving overall heat network effi ciency and consumer comfort. Although implemented in 2023, awareness in the industry has been low with minimal publicity, even though it’s in its third iteration. This is something that needs to change so that all manufacturers are encouraged to embrace the tougher test regime it off ers for all of their HIU range. Back in 2024, Bosch launched the Flow 8500 – one of the fi rst range of HIU to be tested and registered under the regime. This is something that should be the norm, not the exception – only then will the industry see true high-performance HIUs readily available on the market.


Here comes HNTAS


The Heat Network Technical Assurance Scheme (HNTAS) has recognised the need for heat networks to improve their overall performance if they are to deliver the consumer benefi ts and carbon savings that are so needed.


12 February 2026


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