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Blog Post 4 February 2021 Updated 23 November 2022

Making the switch to a low carbon heat pump

Please note: the Green Homes Grant and Renewable Heat Incentive are no longer available.

To tackle the climate emergency, the UK has committed to reaching net zero carbon emissions by 2050. With emissions from domestic heating and hot water currently making up around 77% of total household carbon emissions, we need a revolution in how we heat our homes over the next decade to achieve the necessary savings.

We will need to replace the high carbon fossil fuels currently used to heat our buildings with low carbon fuels and technologies like heat pumps. This will require a significant change to the current UK heating market, for which the majority of the population are largely unprepared.

At Energy Saving Trust, we recognise the need to phase out unsustainable oil and gas heating systems and support the Committee on Climate Change’s target of installing 3.3 million heat pumps across the UK by 2030. We also like to lead by example, with several of our colleagues having already made the switch to low carbon heat pumps.

Here, we learn more about their experiences of installing heat pumps, from applying for loans and planning permission to getting one installed.

The green factor

To reach net zero targets, we’re going to need to dramatically reduce our reliance on fossil fuels to heat our homes and hot water. Heat pumps use less fossil fuel than most other systems, so are a more sustainable, low carbon source of heating.

They work by absorbing heat from a source and transferring it to a fluid, which is compressed to increase the temperature further. The heat is typically transferred from the fluid into water which is used to provide heating for a property, either through radiators or underfloor heating.

These green credentials were a factor in regional account manager Fiona’s decision to install an air source heat pump. “We didn’t want to stay using oil for environmental reasons, the cost and because we needed to re-order oil each time it ran out,” she explains.

A chance to upgrade

If you’ve just moved house and are looking to make upgrades or renovations, use the opportunity to install a heat pump at the same time. When Joanna, a knowledge manager in our insights team, bought an older flat, she decided to upgrade the outdated electric storage heating system to a heat pump. The running costs were cheaper than the old system, and she was able to free up wall space by replacing wall heaters with underfloor heating.

On the other hand, if you’ve just bought a newbuild, there’s a chance it already has a heat pump. Pete, our partnership development manager for the Welsh Government’s Nest scheme, moved into a newbuild almost five years ago, which came complete with an air source heat pump.

Under current government plans, gas and oil boilers will be banned from newbuild homes from 2025. All homes built after this date must be zero-carbon ready, which means heating must come from low carbon sources like heat pumps. The current target is set at installing 600,000 heat pumps a year by 2028.

Joanna installed underfloor heating.

Weighing the options

All but one of our heat pump owners have air source heat pumps, ranging in size from 5kW to 11kW. Air source heat pumps absorb heat from the air to heat your home and hot water; they can still extract heat when air temperatures are as low as -15°C.

Other types of heat pumps include ground source and water source heat pumps. Our blog takes a closer look at the differences between air source and ground source heat pumps. Fundamentally, all heat pumps work in the same way, however ground source heat pumps are sometimes more difficult to install than air source pumps, and they require garden space suitable for digging a trench or borehole.

Water source heat pumps are less common, however our technical manager for transport in Scotland Iain’s father opted for one, using two streams that run through his property. While it’s a more niche renewable technology that extracts heat from a body of water and converts it into energy to heat your home, it’s worth considering if you live near a body of water. Find out whether a water source heat pump could work for you.

Need help covering the costs?

Talking about his decision to install a heat pump, Energy Saving Trust’s renewables technical manager Ben adds the caveat “let’s not forget that this really is a big financial decision.” However, if you’re thinking of upgrading your heating system, there is financial support available to help you install a heat pump. Click on your region to learn more about grants and loans for installing heat pumps.

Once you’ve installed your heat pump, you may be eligible to apply for the Renewable Heat Incentive (RHI) scheme (excluding Northern Ireland), which pays you for the heat your renewable system generates. You need to make sure you apply for RHI payments within 12 months of the commissioning date of your heat pump. If you have been awarded a grant towards the installation cost, this is likely to be deducted from your RHI payments, so it may not be worth claiming both.

The RHI scheme was a decisive factor for all our heat pumps owners at Energy Saving Trust. The payments can help to recover some of the installation costs, or even the entire cost of the heat pump over a longer period.


The finer details: application and installation

Applying for and installing a heat pump is relatively straightforward, however check whether you require planning permission and consider potential disruption during installation. Joanna began her application process not long after the first COVID-19 lockdown, which added some delay, but she was able to select a suitable installer from a range of quotes.

We recommend you get at least three quotes from different installers – and make sure your installer is certified under the Microgeneration Certification Scheme (MCS). Pete recommends “do your research carefully, use an MCS-registered installer and get your claim [for RHI payments] in within 12 months of installing.”

Fiona didn’t require planning permission for her air source heat pump and the installation took just three days. “The installation process was pretty simple,” she says. “The installers decommissioned our oil boiler and installed a new hot water tank, radiators and the heat pump.” Combining the installation with other building work can reduce the cost of installing the system and minimise disruption.

The last word

As a cost-effective, renewable technology that can help to reduce your household carbon footprint, heat pumps will be critical if the UK is to reach net zero emissions by 2050. To put this into numbers, to achieve this target the average UK household must reduce its CO2 emissions from heating from 2,745kg a year (2017 data) to just 138kg – a reduction of 95%.

Ben draws a comparison between owning a heat pump and owning an electric vehicle. “Once you have agonised over details like efficiency, value for money, whether you can afford it or not, is it the right thing to do, you bite the bullet,” he says. “You will definitely never go back.”

Last updated: 23 November 2022