How much does a heat pump and EV cut reliance on imported energy?

The size of the change comes from efficiency rather than generation. Electric heat pumps use about 3 to 4 times less energy than gas boilers to produce the same heat³, and independent analysis of domestic heating options reaches the same figure: heat pumps are usually the most efficient technology for heating homes, using 3 to 4 times less energy than a boiler for the same output⁴. A heat pump still consumes electricity, but the heat energy delivered to the home is much more than the electrical energy used⁵. This is why the answer to "how much" is measured in fuel displaced, not fuel eliminated.

The answer in numbers: it is about efficiency, not output

The core numbers are consistent across independent sources. A heat pump takes heat from the air or ground and uses it for heating and hot water⁶, powered by electricity⁷. Because it moves heat rather than burning fuel, it delivers more heat than the electricity it draws: an official Northern Ireland consultation gives a worked example of an electric heat pump running at 270% efficiency⁸. Nesta's work on the electricity to gas price ratio records the same 3 to 4 times advantage over boilers³.

What that means for imports is the ECIU's finding: the more a household electrifies, the less it depends on foreign oil and gas, and the more it runs on British electricity¹. The carbon side follows the same path. A well designed and installed heat pump system can reduce carbon emissions by 70%, rising closer to 100% as the UK decarbonises electricity generation and supply⁹. Scottish building standards make the same point in policy terms: heat pumps reduce the use of fossil fuels¹⁰.

Two qualifications matter. First, the home still depends on the grid and on an electricity supplier; this is a shift from imported fuel to British-generated electricity, not independence from the network. Second, the bill savings depend on the electricity to gas price ratio³, which is a policy choice as much as a technical one. The Energy Saving Trust reports that a key recommendation for progress on electrification is to remove policy costs from electricity bills to lower heat pump running costs¹².

Who is eligible

The efficiency gains apply to any home that can accommodate the technology, but the financial and tax position varies. VAT relief on energy-saving materials covers air-source and ground-source heat pumps¹³, and water source heat pumps were added to the list of energy-saving materials that can qualify for the reduced rate of VAT¹⁴, including on the list qualifying for a temporary zero rate¹⁵, before reverting to the reduced rate thereafter¹⁶. The relief requires the heat pump to be installed in, or in the curtilage of, residential accommodation¹⁷.

Support schemes have their own definitions. Under the Domestic RHI, a heat pump had to provide space heating or a combination of space heating and domestic hot water; it could not exclusively provide hot water, had to use an electricity-driven compressor, and could not use heat expelled from a building or appliance¹⁸. Air source heat pumps did not have to provide domestic water heating to be eligible, and could also provide water cooling¹⁹. In Scotland, the Home Energy Efficiency Equity Loan pilot covered air source, ground source and water source heat pumps²⁰.

Tariff offers are emerging for exactly this combination of technologies. Ovo offers heat pump installation plus a Heat Pump Plus add-on giving cheaper electricity rates for the energy the heat pump uses²¹, and ivie offered compatible households with heat pumps and EVs a set-priced energy tariff²². These are supplier-specific and depend on compatibility, so a household's running costs depend partly on which supplier it can move to.

Exceptions, conditions and rules for connecting

Several conditions shape what a household can install and how it connects.

• VAT scope: the relief covers heat pumps installed at residential property, and the legislation added electrical batteries that store electricity generated by certain energy-saving materials and from the grid, water source heat pumps and diverters, and certain preparatory groundworks for ground and water source heat pumps²³.
• Planning: air source heat pumps at residential property can fall within permitted development, subject to a number of limits and conditions²⁴.
• Ground source: draft exemption conditions for closed loop ground source heat pump activities in low environmental risk settings remain draft, with an effective date yet to be set²⁵.
• Tariff eligibility: the proposed Interim Heat Pump Tariff Discount would decrease the cost of electricity faced by heat pump consumers by 12% in 2024 and by 24% in 2026 under central price forecast assumptions, but air-to-air heat pumps and domestic hot water heat pumps are not included²⁶.
• Product standards: Scottish building standards reference heat pumps that fulfil the minimum requirements of eco-labelling established in Commission Decision 2007/742/EC, as amended in 2011 and 2013²⁷.

Connection rules matter most where a home's electricity supply is already heavily used. The network guidance is clear that the curtailment arrangements cover import only, meaning the EV or heat pump acting as demand only; they are not applicable to V2G or grid export limitation, which is covered by ENA Engineering Recommendation G100²⁸. Where the existing maximum demand of a premises is above 60A, a Connect and Notify installation is still permitted for a new EV chargepoint or heat pump if there are no issues with the existing connection and the new device has a curtailment scheme that limits overall property demand to 60A or less whenever the device is activated²⁹. Northern Ireland's network operator publishes the same clarification on import or load limiting devices³⁰.

The order of installation and tariff steps

The practical sequence runs from the home's fabric to the connection to the tariff. Insulation comes first because the lower the flow temperature, the better the efficiency of the heat pump, and the lower a household's electricity use³¹. A well insulated home can run a heat pump at lower flow temperatures, which is where the 3 to 4 times advantage over a boiler is actually achieved³.

The connection step is handled by the installer. In Northern Ireland, homeowners or property owners choose the equipment and nominate an EV charge point or heat pump installer, who carries out checks at the property and submits the application to NIE Networks on their behalf³². On the mainland networks, the Connect and Notify route with a curtailment scheme is what allows larger devices onto connections that might otherwise need upgrading²⁹.

The tariff step is where the import story is completed. A household on a standard single-rate electricity tariff may see less benefit than one on a tariff designed for heat pumps, such as Ovo's Heat Pump Plus add-on²¹ or ivie's set-priced tariff for heat pump and EV households²². The proposed interim heat pump tariff discount, cutting heat pump electricity costs by 12% in 2024 and 24% in 2026 under central forecasts²⁶, and the wider recommendation to remove policy costs from electricity bills¹², would narrow the electricity to gas price ratio that currently works against electrified homes³.

What remains after all of this is dependence on the grid, on a supplier's tariff, and on the pace at which British electricity generation decarbonises. What goes is the gas boiler's pipe of imported gas and the petrol car's tank of imported oil. For a fuller picture of where a home's imported energy actually goes, see household import dependence, and for the wider picture of household energy independence.