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James Chaplen highlights a role for heat pumps in the next generation of heat networks

The Government is targeting 600,000 heat pump installations per year by 2028.

The aim is to move the UK away from its reliance on fossil fuels (largely natural gas) for its space heating and hot water production.

Highly energy efficient heat pumps will enable households and businesses to make use of our increasingly renewable electricity.

They’re also a well-known technology that has already been applied in thousands of buildings (domestic and commercial) across the country.

Heat networks, which can serve individual buildings or even whole towns, are another important low-carbon technology for the future of UK heating.

Currently, they only represent around 2% of heating systems, but the ambition of the Climate Change Committee is to increase their use to 42% by 2050.

One of the issues with many of the heat networks in use today is that they rely on fossil fuels such as gas to produce the heat required.

While this is still a lower-carbon option than multiple individual gas boilers, it’s not ideal.

Harnessing renewable energy alongside heat recovery takes us further along the road to net zero

James Chaplen James Chaplen Senior Product Manager

Overheated buildings

What’s more, because these networks operate at temperatures between 55oC and 70oC, they can contribute to overheating in buildings.

A study by BRE identified that this is often due to poor pipework insulation.

But it can also be the result of low heat demand on the network, which continues to maintain those high temperatures – wasting energy and contribute to overheating.

However, there is a growing interest in combining heat pumps and heat networks to create a next-generation heat network system that operates at temperatures as low as 10oC to 30oC.

This means no heat loss or contribution to overheating in the system.

A low-temperature heat source

Fifth Generation heat networks (as they are known) circulate low-temperature water around an ambient energy loop.

Each building or apartment on the loop has a heat pump installed that provides domestic hot water and space heating.

But these energy loops don’t simply act as a heat source – they can also be a heat sink.

So, if the building or group of buildings includes cooling systems, rejected heat can be sent into the loop. By using heat recovery, the whole network is more efficient and reduces primary energy consumption.

A heating and cooling vision

Mitsubishi Electric has been developing its expertise in heat pumps for many years. Our heat pumps range from domestic to commercial and recently we have added to that range with our new Ecodan Hydrodan, which a water-to-water heat pump designed to work in Fifth Generation heat networks.

Our vision is that heating and cooling works on a single system, seamlessly transferring heat around the ambient loop which is kept in balance by heat pump technology. Primary energy consumption is reduced, relieving pressure on our electricity grid as we shift away from fossil fuels.

The system is particularly valuable when applied in mixed-use developments. For example, a building which has apartments over retail outlets and a gymnasium which use water-cooled VRF for cooling.

Heat rejected from this system in cooling mode can be transferred into the ambient loop. The Ecodan Hydrodan units in each apartment use this heat to meet residents’ domestic hot water needs.

Important synergies

The Ecodan Hydrodan units have been designed with a small footprint and an integrated water tank.

This means they fit easily into a utility cupboard and can be accessed for trouble-free maintenance. Operating a very low noise levels, the unit provides residents with water on tap and comfortable space heating.

As we move forward into a new low-carbon heating era, applying well-known technologies in new ways is an ideal solution.

Engineers and contractors understand the principles behind these systems and have the knowledge to make them work effectively.

By harnessing renewable energy alongside heat recovery, we gain important synergies – taking us further along the road to a net zero future.

James Chaplen is Senior Product Manager at Mitsubishi Electric