Opinion piece by Tom Lowe, Founding Director at Thermal Storage UK

Almost everyone agrees that electrification will play a major role in decarbonising heating. That includes independent experts working for the UK and Scottish governments, the Climate Change Committee, the National Infrastructure Commission and the Energy Systems Catapult.

Electrification of heat involves a range of heating technologies, including air-source and ground-source heat pumps, heat networks and thermal batteries. Rooftop solar will also have a role to play, particularly for domestic hot water. The technologies for electrifying heating across all types of homes already exist.

To give a sense of the scale of the change required to achieve net zero, by 2050 almost every home in the UK will have a new heating system and many will have had fabric improvements. The UK is looking to upgrade 375 homes every hour every working day for the next 26 years. It is a major infrastructure challenge.

One of the key questions for electric heating is how best to reduce or minimise peak demand. Electrification without flexibility could quadruple peak demand in winter, with these peaks occurring in the morning and evening. In the absence of intervention, that means more expensive reinforcement of the electricity grid at distribution and transmission levels. The UK already needs to build more transmission network in the next 7 years than in the past 30 years. This is paid for by people and businesses. Ensuring that electric heating systems are flexible lowers the amount of network investment required and makes the most of renewable electricity. This involves shifting when electricity is consumed by storing heat in dedicated thermal batteries or preheating energy efficient homes.

As building professionals know only too well, upgrading homes is a much more personal intervention than decarbonising the power system or transport. We can build wind turbines out-of-sight in the North Sea or solar in low-grade fields. We can install EV chargers at home or in street lamps that are discrete and straightforward to wire.

In comparison, upgrading heating systems and installing measures such as insulation require deeper changes to people’s homes. That might include lifting floorboards and carpets, redecorating walls where internal wall insulation is fitted and changing window recesses. In many homes, this may mean moving or removing cupboards for hot water cylinders. For instance, installing a 200 litre hot water cylinder involves taking up the equivalent space of a tall fridge-freezer. That is premium space for a homeowner that they might not have. Innovative companies such as Sunamp have developed phase change material thermal batteries which are highly flexible, efficient and very compact.

Working inside people’s homes requires extra care and attention. This means heating engineers possessing a good understanding of the PAS 2035 framework for retrofit and working with retrofit coordinators to consider insulation, ventilation and heating distribution.

It also means giving customers options between different heating technologies. For most homes looking to electrify, this is primarily a choice between heat pumps and thermal batteries. The Energy Systems Catapult has shown through the Electrification of Heat demonstration project that all types of home can have a heat pump and thermal store system installed. In practice, some homeowners may struggle with planning restrictions, limits to internal or external space or not want to invest in their building fabric. The Prime Minister acknowledged in September 2023 that it is harder to install heat pumps in some homes. Highly flexible technologies such as tepeo’s Zero Emission Boiler can work in homes where heat pumps are more difficult to install.

Governments recognise the importance of thermal batteries in keeping homes warm and providing flexibility to the electricity grid. The Scottish government’s Home Energy Scotland provides grants and loans for thermal batteries. The UK government has included thermal batteries in its proposed standards for the forthcoming Smart Heat Mandate.

However, in many areas the policy landscape is playing catch up with innovation in flexible electric heating. Various barriers to electrification of heat remain. Some of these barriers are deep within UK energy policy. Electricity wholesale prices are set by marginal gas generation and net zero policy costs being loaded onto electricity bills. The UK government has opened a major programme of work through the Review of Electricity Market Arrangements (REMA) and committed to start to address the imbalance in gas and electricity prices during 2024. Ofgem has started to allow networks to build the electricity grid in advance of need and the UK government is making it easier to build critical network infrastructure.

But much more work is required to address barriers to maximising flexibility. This means valuing flexibility, including from heating. Time-of-use or type-of-use tariffs will become much more common, encouraging people to use their heat pumps and charge their thermal batteries when wholesale prices are low. To achieve this, Ofgem must deliver half-hourly settlement by 2026 at the latest and energy suppliers must complete the smart meter roll-out in the next few years.

There is also a role for the tax system to encourage flexibility. While the UK’s flagship Boiler Upgrade Scheme provides a grant to super-efficient heat pumps, the grant is not yet available to highly flexible thermal batteries. While the government has extended zero-rated VAT to electro-chemical batteries until 2027 and confirmed thermal batteries qualify when they are ancillary to an energy saving material, further work is required on definitions to bring thermal batteries into scope.

Beyond the realm of buildings, there is a momentous challenge for UK businesses to decarbonise industrial heat processes. Britain has a long heritage of innovative manufacturing and we want to keep making things in the UK in a net zero world. This means moving away from fossil fuels such as gas or oil. Companies such as Caldera have developed large thermal batteries to support companies to electrify industrial heat processes.

Ultimately, this is a message of hope. Innovative companies, including British companies such as Sunamp, tepeo and Caldera, have developed the technologies to decarbonise and electrify large chunks of energy demand currently met by fossil fuels. Everyone involved in the heating and building sectors has a role over the next 25 years in delivering the largest ever upgrade to homes to deliver low carbon, flexible heating.