Heat pumps can be a divisive topic but in cities of the future, they may be ubiquitous.
The heating systems are being widely promoted because they cause less carbon emissions than gas central heating, which is currently used by three quarters of UK homes.
Some homeowners are cautious, though, because installing a heat pump generally requires a large initial investment and disruptive building work.
However, a small but growing number of homes are part of futuristic “district heating systems”, supplied by communal heat pumps connected to streets of houses or blocks of flats.
Such super heat pump systems are predicted to save people hundreds of pounds a year on their energy bills. They lead to energy bills that are 40 per cent less than with individual heat pumps for each building, according to district heating firm Vital Energi. They are also even more carbon efficient, which is vital for the country’s net-zero ambitions.
They are already operating at a few sites around the UK and the Government has announced plans for seven more district heating systems, in Leeds, Plymouth, Bristol, Stockport, Sheffield, and two in London. They could meet a fifth of total UK heat demand by 2050, according to the last Government’s Net Zero Growth Plan.
Instead of homes being connected to the gas supply, super heat pumps have pipes that deliver hot water.
Some of the systems have water-source heat pumps, which use heat energy from rivers, through a network of pipes that lie under the water. Others, called ground-source heat pumps, have been installed underneath roads.
Customers have control over how much hot water they use, and how much heat to supply to their radiators, and are billed accordingly.
But, because any kind of heat pump system is more efficient than gas boilers, energy bills are generally less, said Bean Beanland of the Heat Pump Federation.
One of the first district schemes in the country is taking heat from the River Clyde in Glasgow, where there has been a £250m regeneration scheme at a former docklands area called Queens Quay.
The water-source heat pump system has been connected to many of the new office blocks and public buildings in the development since 2020.
In 2024 the same heat pump system began supplying heat and hot water to two blocks of flats. While one was a new build, a more complex project was to retrofit the system into a 1919 block of tenement flats.
These flats had previously been using electric storage heaters, which lead to higher energy bills, said Jack Devlin of Clydebank Housing Authority, which manages the building.
With the new system, heating bills are generally £60 to £70 a month. That compares with about £140 in similar tenement flats that have gas-powered heating, said Devlin.
Elizabeth Thom lives in a Glasgow flat where the hot water and heating takes heat energy from the River Clyde. The flats used to have storage heaters, which use electricity to heat a tank of water, a relatively expensive way to heat a home.
But her tenement block is located near the new Queens Quay waterfront regeneration scheme, which has a district heat network, where hot water is generated in a plant next to the river, and piped to the new offices and buildings. So, Clydebank Housing Association used green subsidy schemes to connect her building to the network, too. She pays a monthly bill based on how much hot water she uses.
This is the first winter since the new heating system was installed. Last month, her heating bill was £56. Combined with her monthly electricity bill, the total was about £100. With the previous storage heater, her electricity bill could be up to £140 a month in winter, she said.
Mrs Thom is satisfied with the warmth when her heating is turned on, although she still limits how much she uses it because of the cost-of-living crisis, only turning it on for a couple of hours every evening. “Once you get it on, it is warm. It’d be great if you could put it on for longer and generate the heat constantly,” she says. “But I’m happy with the system.”
An even bigger scheme is planned for a network of public buildings, businesses and apartments in central London, using heat from the River Thames.
Landmarks such as the Houses of Parliament, Westminster Abbey and the National Gallery have been identified as suitable buildings for the system.
A network of underground insulated pipes will carry hot water at 80°C through an area stretching from Victoria Station to the Strand, bordered by St James’s Park to the west and the Thames to the east.
The work will be funded by two district heat network companies, Hemiko and Vital Energi, which have formed a collaboration called the South Westminster Area Network (Swan) Partnership. The plan has backing from the Department for Energy Security and Net Zero, and Westminster City Council.
The Swan Partnership is currently in talks with potential customers, whose names are still confidential, said Charlotte Owen, growth director at Hemiko. “At the moment, we have really strong enthusiasm and will to join the network among lots of different buildings, ranging from the public sector through to big hotels, major banks. We’re still under confidentiality agreements with them, but the network is very much happening.”
Some blocks of residential flats in the Westminster area will also be able to join the heat network if they currently have a communal gas boiler in their basement that serves all the flats, she said. “There are a few buildings that have approached us and said: ‘We are a group of tenants that are really motivated by decarbonisation, and we want to join the heat network.’”
A district heat network is also up and running in Stithians, a small village in Cornwall, although this uses ground-source heat pumps.
Ground-source pumps require digging either a network of trenches or deep bore holes – usually in people’s gardens. But in Stithians, a communal network of bore holes has been dug under the roads, which all the connected houses share. Pipes take the warmed water to a heat pump in each home.
A district heat network was considered for Stithians because the village is not connected to the mains gas supply, so most homes were using electric storage heaters. “If we’re taking people off storage heating, we tend to see 40 to 50 per cent reduction in bills,” said Wouter Thijssen, director of Kensa, the firm that installed the district heat network in Stithians.
“The challenge has always been that for an air-source pump, you put a box outside your house, and for a ground-source pump, you need to drill a hole and that costs more.
“But when we start linking all of these holes together and having one utility company pop up to your street, and drill all of them and then charge people a monthly fee, that’s when we see ground-source getting rolled out,” said Thijssen.
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