The UK Heat Interface Unit (HIU) testing regime developed as part of a government-funded project in the UK has been praised by judges at an international district heating conference.

The testing regime designed for UK operating conditions was the culmination of a year-long project carried out by energy consultancy FairHeat on behalf of the UK government’s Department of Business, Energy and Industrial Strategy (BEIS).

A paper, presented on the testing regime by Martin Crane of Carbon Alternatives (who worked as an integrated member of the project team), was named best presentation and awarded €1,000 in prize money at the 4DH Conference in Aalborg, Denmark.

The 2nd International Conference on Smart Energy Systems and 4th Generation District Heating (4DH) brought together experts from around the globe to investigate the potential for and develop 4th generation district heating.

Professor Sven Werner, world renowned expert on district heating from Halmstad University in Sweden, was part of the judging panel. He said:

“Fourth generation district heating systems and technologies will play a big part in future cost-effective sustainable energy systems and are likely to replace the import of fossil fuels and create jobs and economic growth in Denmark and in Europe.Our senior winner is a person working close to reality. The committee was impressed by his presentation of a substation test ensuring performance in real district heating systems.”

The test regime was developed as part of a government project to improve the energy efficiency of heat networks.

District heating is already well established across Europe, and in Sweden HIUs required to be certified to the Swedish District Heating Association F:103-7e.

Martin Crane of Carbon Alternatives (centre) pictured with Jan Eric Thorsen of Danfoss (left) and Professor Sven Werner (right) receiving an award at this year’s 4DH Conference in Aalborg, Denmark.
Photo credit: May-Britt Vestergaard Knudsen.

As part of a wider project using data to improve energy efficiency on heat networks, F:103-7e was evaluated for use in the UK. The project team found that while aspects of the Swedish regulations are appropriate for the UK, there are significant differences between the operational parameters of heat networks in Sweden and the UK.

Gareth Jones, Managing Director of FairHeat, said: “Aspects of the Swedish regime simply don’t apply to the UK, for example here is no requirement to test to 120°C, as UK heat networks do not typically operate to these temperatures.

“HIUs have a major impact on the overall performance of any heat network and if HIUs perform poorly then it is very difficult to limit network losses and achieve a low cost of heat.This regime sought to provide a framework for HIU manufacturers to evaluate the performance of their equipment within the UK context, and provide data on the impact of different design and installation choices on HIU performance to operators.”

The project team took the Swedish test regime and modified it to suit typical UK heat network operating parameters, selecting the same testing body that operates the Swedish testing regime (SP Technical Research Institute of Sweden), and paid for modifications to the standard Swedish test rig.

The initial regime developed as part of the project has seen six leading manufacturers send their components to be tested, the results for which have been published online.

Martin Crane of Carbon Alternatives said:

“It’s very flattering to be selected for this award by such an esteemed group of the world’s experts in energy efficient district heating.  Over the years I have learnt much from their research.  It’s great that they value the HIU testing regime we have developed in the UK.  Many thanks to the DECC/BEIS for funding the research.The test has already got HIU manufactures improving and retesting their products to achieve lower return temperatures under the real world test conditions.  The test has also prompted, the overdue, consideration of how the efficiency of DH network can be achieved in practice, specifically consideration of standby performance.  The test, through the calculation of a volume weighted return temperature (VWART) for each HIU tested now provides a more robust route to specifying a HIU that will be efficient in operation and puts, long absent, focus on the correct setup of the radiator in the heating system.”

Following the completion of the project, a steering group made up of representatives from BESA, BEIS, CIBSE, Engie, E.ON and SSE has worked with FairHeat and Carbon Alternatives to finalise the testing regime with the input of leading manufacturers.

The finalised regime is due to be released in November.
To find out more about the regime or the project please go to:

The award-winning presentation can be found at