Technology alone is not enough. If we are to decarbonise heat and convince 30 million homes to switch to low carbon heating, we need innovation, investment and policies to increase deployment and support residents and businesses to make the move away from traditional heat systems to low-carbon and electrified systems.

While lockdown has brought about a significant drop in carbon emissions as well as a clearer London skyline, the economical and societal impacts of Covid-19 have served to amplify the urgent need to build resilience to climate change. The build back better message has been taken to heart by national and local government, as well as consumers and businesses. The support offered by central government is an enabling factor – and now the public sector as a whole needs to step up to tackle carbon emissions in heat. Heat represents nearly 40% of UK emissions – we will not get to net zero without radical change here.

The UK’s commitment to net zero carbon by 2050 requires a large-scale transformation in the way in which energy is generated, distributed, and consumed. The past decade has seen considerable advances in decarbonising the power sector. The closure of coal-fired power stations and the increased proportion of renewable electricity in the grid (both large-scale schemes and individual buildings and developments) have contributed to the plunge in electricity carbon intensity, which is predicted to be as low as 50g CO2e/kWh by 2030 and must be less than 20g CO2e/kWh at net zero. However, heating remains the largest source of greenhouse gas emissions in the UK, and decarbonisation efforts lag well behind power, waste and industrial emissions.

Why do we need to decarbonise heat?

“Heating is central to our lives. In our homes, we rely on it for comfort, cooking and washing. Businesses need heating and cooling for productive workplaces and heat is integral to many industrial processes. It is the biggest reason we consume energy in our society.”

Department for Business, Energy and Industrial Strategy

At 37%, heating accounts for the largest proportion of UK greenhouse gas emissions. Fossil fuels deliver most of the heating in our buildings and industries; and natural gas remains the predominant heating source for most customers connected to the grid. At the current rate, it is estimated that it would take 1,500 years to decarbonise the heat sector. While the scale of the challenge may appear daunting, the time for action is now.

For a number of reasons, the decarbonisation of heat is the greatest challenge the UK faces to become a net zero carbon economy.

Scale of the challenge – Around 85% of the 28 million UK households are connected to the gas grid. Only about 5% of homes currently have low carbon heating – mainly comprising electric heat pumps, wood burners and biomass boilers. We need to be converting 20,000 homes a week (1 million annually) by 2025 to hit our 2050 targets.

No silver bullet solution – As is so often the case, there is no ‘one size fits all’ approach to decarbonising heat. Moreover, estimates suggest that mandating a blanket solution such as all-electric is projected to cost 2-3.5% more than a tailored approach looking at solutions at an individual building level.

Poor energy efficiency –  UK building stock is the worst in Europe, with approximately half of it owned by local authorities. Retrofitting low carbon heating poses a challenge as technologies operate most effectively in conjunction with energy efficiency upgrades. This has led to increased demands for new standards for zero carbon homes and commercial properties. While this is vital for improving the quality of our new build stock, we still need to address our existing buildings – 85% of which will still be occupied in 2050.

Current heat decarbonisation policies are not working – Policies like the renewable heat incentive (RHI) and the ECO scheme have failed to have the desired effect. Simply put, the high upfront cost of renewable heating systems reduces the viability for most households. Over nearly four years, only 60,000 renewable appliances were installed under the Domestic RHI, compared to 6.2m gas boilers. As a result, other policies are having to work harder to enable the government to meet its legal obligations. The capital injection from central government through mechanisms like the Green Homes Grant is obviously welcome, but with such tight timeframes to implement, many households will be left behind. Long-term programmes of support are needed to ensure the net zero transition is equitable.

Resistance to change – Unlike the power sector, heat decarbonisation has a direct effect on consumers as it often involves upgrading technologies within the home. About 90% of UK homes still use gas boilers, many of whom are opposed to removing a technology which has long been accepted as a comparatively efficient and convenient heating source.

How can we make zero carbon buildings?

  • Heat pumps are the most efficient way of using electricity to heat your home. They offer a modern, low-carbon solution to provide space heating and domestic hot water. Heat pumps are particularly appropriate in countries which have both high heating requirements (in winter) and cooling requirements (in summer). Manufacturers offer either air-source and ground-source heat pumps, which sit outside a building and extract warmth from the air or ground to heat water for radiators.
  • District Heating involves a system of highly insulated pipes delivering heated water to radiators in numerous homes and buildings. Heat is generated from a central boiler plant or other heat source, such as a biomass or gas-powered ‘combined heat and power plant’ or local waste heat from industry.
  • Other prospects to help achieve net zero in buildings include hydrogen boilers and Heat as a Service, although these remain in the early stages of development.
  • Biogas injection to the grid will also contribute to decarbonisation for homes that cannot move away from gas, however, currently only 30% of biogas production is upgraded to biomethane suitable for injection into the gas network. Policy and Regulation will be required to incentivise biomethane injection into the gas networks.

But technology alone is not enough. If we are to convince 30 million homes to switch to low carbon heating, we require a combination of innovation, investment and incentives policies to expand on the current uptake and provide consumers with the confidence that new technologies can be as efficient, cost-effective and reliable as the traditional systems.

Government targets and increasing public awareness of the immediate action required to combat the effects of climate change have thrust heat decarbonisation to the forefront at a national and local level. With multiple stakeholders comes the urgent need for leadership and a clear path to net zero if we are to meet our targets for 2050 and beyond.

Other barriers to decarbonising heat

We find that the barriers to decarbonising heat are not usually the technology. While some energy users may be uncomfortable with moving away from fuelled systems including heating oil and gas, the real stumbling blocks come in the commercial case for change. Our engagements with communities often reveal that individuals are convinced of the need for change, but they’re not prepared for it to cost more in the short term. Having in principle won hearts and minds, we need to do more to quantify and monetise the benefits of low carbon heat for end users.

At the moment the business case for changing away from gas (cheap) to electrified heat (more expensive) is not straightforward. For the typical home-owner or business user, the switch to low carbon heat is more expensive – largely because we don’t usually consider the whole life cost of heat when making this decision. Heat tariffs usually account for costs like O&M and life-time replacement costs – which we do pay for as gas boiler users, but normally in an emergency! Therefore the “unit cost” comparison of a heat tariff compared to gas is always unfavourable.

We also don’t currently account for the social costs of carbon-intense and traditional heat sources. Without a meaningful cost of carbon or air quality, gas will always out-perform electrified heat.

And finally, there is general resistance to change. This is understandable – we have a reliable low-ish incumbent heat system in the UK – the natural gas grid. So it is a challenge to try to convince someone to switch away to something that is perceived to be less reliable, more expensive, and a hassle! Energy users need to understand that the choice is not really between natural gas and air source heat pumps, because shortly policy will not permit install of new gas systems. We anticipate that this will extend to phasing out all fossil fuel heat systems in due course. So energy users are choosing whether to decarbonise now, when it is within their control, or in a few years’ time, when it will be enforced. We have a duty to communicate this to residents and businesses clearly and winsomely, so that they make an informed choice.

Government targets and increasing public awareness of the immediate action required to combat the effects of climate change have thrust heat decarbonisation to the forefront at a national and local level. With multiple stakeholders comes the urgent need for leadership and a clear path to net zero if we are to meet our targets for 2050 and beyond.


For more information on tackling the challenges on decarbonising heat, please contact: Daniel Collins

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