Electrification alone won’t solve the heat challenge

Christophe Williams, CEO and Founder of Naked Energy, explains why electrification alone will not solve the UK’s heat challenge and why renewable heat must become part of the conversation.

Heat is the largest energy end use in the UK and is responsible for a third of all emissions. Heat is difficult to decarbonise as it covers various temperature ranges and applications. It really is the biggest challenge on the journey to net zero.

And yet, decarbonising heat is often presented as a straightforward electrification challenge. The narrative usually goes that all that needs to be done is to replace gas boilers with heat pumps.

While electrification is fundamental to reaching net zero, it does not mean every unit of low-carbon heat should first pass through the electricity system.

For electrical engineers, building owners and energy managers, this matters. Heat represents a significant source of energy demand across industrial, commercial and public-sector buildings. If we try to electrify all of it at once, we risk creating another problem: buildings that are lower carbon but require larger electrical connections, more network reinforcement and additional peak capacity that can be expensive or commercially unviable to secure.

Businesses are already facing long waits for new or upgraded grid connections, while concerns around network capacity and resilience are becoming harder to ignore. Heat pump deployment also needs to accelerate significantly if the UK is to meet its decarbonisation ambitions.

Do we need to stop electrification in order to reach net zero?

Of course not, but we should be treating renewable heat as a component of electrical infrastructure planning.

Solar thermal technologies can generate useful heat directly at the point of use. Instead of converting sunlight into electricity and then using that electricity to produce heat, solar thermal captures the heat itself. Solar photovoltaic-thermal (PVT) technology combines the two, producing electricity and heat from the same rooftop area.

Hotels, hospitals, leisure centres, care homes and university estates share a constant hot water demand that runs all year. Solar thermal can meet a share of it without adding to the building's electrical load.

Solar thermal can also provide preheating alongside a heat pump, reducing the amount of heat the pump needs to supply. Where a heat pump handles most of the demand, solar thermal can therefore improve the efficiency of the overall system. Where thermal storage is included, the electrical connection may also need to serve a lower peak load.

The opportunity is to design and build more balanced systems in which different technologies do the jobs they are best suited to.

That approach can have important consequences for connection capacity.

A building considering a major heat electrification project may discover that its existing electrical connection cannot support the planned load. Upgrading that connection can be expensive, slow or constrained by wider network limitations.

Reducing peak electrical heat demand can therefore change the economics of a project. Where part of the heat requirement is met directly from an on-site renewable source and buffered with thermal storage, the electrical capacity required for the heat pump can be reduced.

A modest reduction in peak demand can be the difference between paying for a routine connection and a more extensive network upgrade. Repeated across a large estate, that same effect reduces the cumulative load that heat decarbonisation places on local networks.

How can commercial and industrial buildings assess how to supply their heat demands?

A building’s energy demand needs to be viewed holistically.

What is its heat profile across the day and year? When does electricity demand peak? What grid capacity is available? How much roof or façade space can be used? Could on-site renewable heat reduce the electrical demand of a heat pump, or the electrical connection capacity or storage required?

These questions should sit alongside decisions on solar PV, batteries, EV charging and other applications.

Solar thermal has arguably been the Cinderella of the solar sector for too long, overlooked as attention and investment have flowed towards electricity generation. But this is beginning to change. The recent £8.875 million investment in Naked Energy, led by Great British Energy alongside Barclays Climate Ventures, is one indication of growing appreciation of truly renewable heating technologies.

Do we need to think beyond the grid in order to meet net zero?

Meeting net zero will take more renewable generation, a stronger network, more storage and many more heat pumps. Electrification provides the backbone, but we cannot achieve net zero in a reliable or affordable way if every low-carbon heat decision simply adds another electrical load.

The question at the start of every project should be: how do we decarbonise this building’s heat demand while placing the least possible strain on the grid?

Asking this question early changes how we design products. In buildings where hot water is a year-round load rather than a seasonal one, such as hotels, leisure centres and care homes, generating renewable heat at the point of use can reduce electrical demand. This can be the difference between a project proceeding this year and sitting in the connection queue.