District heat networks should not be overlooked, writes Jennifer Castle, chief operating officer at LHCPG
Like an extra overshadowed by the lead actors, one section of the Warm Homes Plan drew little attention when it was announced.
Heat pumps? Centre stage. Solar panels? Politicians were shouting from the rooftops about those. District heat networks? Hardly got a mention.
But as no book should ever be judged by its cover, so the merits of district heat networks should not be overlooked simply because of the uninspiring name; they are, in fact, a key part of the push towards net zero and integral to heating thousands of homes cheaply.
District heat networks (or district heating) provide heat and hot water, or sometimes steam, to multiple buildings from a central source via insulated underground pipes, acting like “central heating for cities” by eliminating individual boilers.
Internal heating systems
In each building, heat is transferred from the pipes to an internal heating system via heat interface units (HIUs) or substations, which effectively pass the heat into radiators or hot water systems inside homes or offices.
A bit of technical detail now on the substations, which normally have one or more of the following parts:
- A heat exchanger to split the primary and secondary side of the system.
- A control valve to regulate the flow through the heat exchanger.
- A heat meter to measure energy consumption and allocate costs.
- A “strainer” to remove particles that could block the heat exchanger or control valve.
After passing through heat exchangers at the customer end, the cooler return water comes back toward the energy centre to be reheated and sent out again. The system uses flow and return pipes to ensure that heat circulates efficiently around the network.
Some of the benefits of the system are that it offers economy of scale, cuts many maintenance issues in larger-scale developments and, importantly, uses heat from some really interesting sites that would otherwise have gone to waste.
Take data centres, for instance, specifically the Danish city of Odense, home of Hans Christian Andersen.
Since 2020, Meta’s hyperscale data centre, spanning 50,000 sq m on an industrial estate on the edge of the city, has been pushing warm air generated by its servers into the district heating network under the city. That heat is then dispersed through 100,000 households hooked up to the system, with Meta providing enough heat to cover roughly 11,000.
In Ireland, an Amazon data centre already helps heat TU Dublin, the country’s first technological university, while Microsoft is building what is expected to be the world’s largest data centre heating system in Espoo, a city in southern Finland.
Using waste heat to warm homes and other buildings is common practice in northern Europe, particularly in Nordic countries, where sources of waste heat – including data centres, power plants, incinerators and sewage plants – are required to connect to heat networks.
Fuel poverty hotspots
Why does this matter for the UK? Well, look at the statistics in new analysis from energy platform EnergiRaven and Danish sustainability consultancy Viegard Maagøe: waste heat from the UK’s rapidly expanding data centre sector could produce enough heat for up to 6.3m homes by 2035, but only if the government acts now to help accelerate the roll out of heat networks across the country.
“Our national grid will be powering these data centres – it’s madness to invest in the additional power these facilities will need and waste so much of it as unused heat, driving up costs for taxpayers and bill payers,” said Simon Kerr, head of heat networks at EnergiRaven.
From a government perspective, district heat networks make absolute sense. From this year, Ofgem will take over regulation of heat networks and new technical standards will be introduced through the Heat Network Technical Assurance Scheme (HNTAS) to help boost consumer and investor confidence.
The Warm Homes Plan also sets a target of doubling the proportion of heat demand met by heat networks in England to 7% – or 27TWh – by 2035, while heat networks are expected to supply around a fifth of all heat by 2050.
To support these and other targets, the government has pledged an injection of £1.1bn for heat networks, including £195m per year to 2030.
Momentum is gathering and there needs to be a delivery system that keeps up. For me, that involves frameworks.
LHCPG’s N9 framework workstreams
Our own Retrofit & Decarbonisation (N9) framework includes a category within Workstream 4 for District & Network Heating Systems.
Including design, installation, upgrade and integration of networked heat solutions, the framework provides a proven route to delivering the kind of low-carbon heating systems many local authorities and housing associations could benefit from.
The framework’s structure also covers consulting, strategy, funding support and multidisciplinary works that support heat network projects as part of broader retrofit and decarbonisation goals.
Heat networks are vital to making net zero a reality in the UK. In high density urban areas, they are often the lowest cost low carbon heating option.
They offer a communal solution that can provide heat to a range of homes and businesses by capturing or generating heat locally.
By driving forward new low carbon technologies like heat networks, the government says Britain can cut the use of fossil fuels for heating homes and shield households from oil and gas price rises that are being pushed up by pressures on global energy markets.
District heat networks… an uninspiring name maybe, but a key player in Britain’s journey to a net zero future and delivery of a comfortable, warm life for tens of thousands more households.
*Please note that this is a commercial profile.
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