Heat pumps seem to defy the laws of physics – and can slash building emissions. Here’s how

Heat pumps offer 300-400% efficiency compared to 70-95% for typical gas boilers, so why don’t more buildings have them? Here’s everything you need to know.

If a bank account offered a 300% interest rate, only a fool wouldn’t put their money there.

Heat pumps offer similar returns for energy use, providing 300-400% efficiency. That compares with around 70-95% efficiency for typical gas boilers, meaning users get up to a third less energy out of them than what goes in.?

These efficiency gains mean heat pumps powered by renewable energy can cut building emissions significantly. So why doesn’t everyone have, or even want, a heat pump?

High upfront costs are the main reason. The running costs can also be higher than those of gas boilers, though they can be lower, too, depending on changes in the relative prices of gas and electricity.

No matter how much some people want to cut their emissions, the significant outlay to switch to a heat pump – at a time when inflation has already jacked up the cost of living – can be too big a hurdle to jump.?

Uptake is still rising though, particularly in countries where governments are offering to help households with the cost. In mainland Europe, this is happening as part of a push to get away from Russian gas.

But heat pumps are generating much less interest in other countries. So, what do we have to do to make heat pumps universally appealing?

How heat pumps work

Heat pumps do not work like traditional gas boilers. They actually work like something else you have in your house – a refrigerator, but in reverse.

Instead of creating heat by burning fuel, heat pumps move heat around, pulling it into a building from natural sources nearby. Transferring heat from one place to another is exactly what fridges do, except they take heat and push it out of the fridge.

There are several different types of heat pump, each designed to make use of different sources of heat. Ground source heat pumps draw on geothermal energy in the Earth, while water-to-water heat pumps take heat from underground water sources.[1] Air source heat pumps, also known as air-to-water heat pumps, absorb heat from the air outside instead.

Where are heat pumps booming?

Heat pump installations have been rising by up to 50% per year in some parts of Europe. Sales in Germany have boomed, as the chart below shows.

The United States is also seeing rising interest in heat pumps, with sales exceeding those of gas boilers for the first time.

Germany’s heat pump boom has been helped by a rebate scheme covering up to 40% of the cost of purchase and installation[2], while the US is covering up to 30% of the cost for some pumps.[3] Many European governments have also introduced subsidies for heat pumps in new builds or renovations.[4]

But this is not always enough to fully offset the difference in price between a boiler and a heat pump.

The hurdles facing heat pumps

The price pressure on consumers meant Germany’s move to ban the installation of gas boilers by the start of 2024 was seen as too swift by 75% of the population. Berlin listened and has now pushed back the change to 2028.[5]

Still, installations are rising in Germany, as mentioned. This contrasts markedly with the UK, which has not yet put any rules in place on installing heat pumps – although a bill is moving through Parliament[6] – and is consequently running behind at least 20 other European countries on installation rates.[7]

UK consumers have also raised objections to heat pumps over their appearance, although companies are working to rectify this with significantly different designs, and it could break down some barriers.[8]

Stricter building codes on energy efficiency could also encourage uptake of heat pumps, especially for new builds.

However, simply fitting homes with heat pumps will not be the full answer. A rapid, large-scale switch away from gas toward heat pumps has the potential to drive up electricity use to an excessive degree during periods of peak winter demand, putting major strains on power grids.

This will need addressing, and cutting overall energy use by fitting more insulation and better windows into buildings is one way to reduce the pressure on grids.

Powering progress

The buildings in which we live and work are among our greatest climate liabilities. They are responsible for 6% of global CO2 emissions – or triple that if you count the emissions from the electricity they use[9] – and are one of several sectors where relatively little progress is being made.

Yet even a wasteful building can eliminate its emissions if it is fitted with a heat pump powered by renewable electricity. Making heat pumps attractive and affordable for all households is the clear way forward, and governments will bear much of the responsibility for making that happen.

Read our full Sustainability Trends Report to find out more about heat pumps, building emissions, and where the world is on its journey to a cleaner future.

[1] Spectra, From hybrid to air-to-water: How different heat pumps work – https://spectra.mhi.com/from-hybrid-to-air-to-water-how-different-heat-pumps-work

[2] BBC, Which European nations are winning the heat pump race? – https://www.bbc.co.uk/news/business-65317369

[3] US Environmental Protection Agency, Heat Pumps – https://www.epa.gov/burnwise/heat-pumps#:~:text=The%20federal%20Clean%20Energy%20Tax%20Credits%20for%20Consumers%20covers%2030,be%20used%20for%20other%20projects.

[4] European Heat Pump Association, Subsidies for residential heat pumps in Europe – https://www.ehpa.org/wp-content/uploads/2023/03/EHPA_Subsidies-for-residential-heat-pumps-in-Europe_FINAL_April-2023.pdf

[5] Euractiv, Germany adopts watered-down fossil boiler ban for 2028 – https://www.euractiv.com/section/energy-environment/news/germany-adopts-watered-down-fossil-boiler-ban-for-2028/

[6] UK Government, Energy Security Bill factsheet – https://www.gov.uk/government/publications/energy-security-bill-factsheets/energy-security-bill-factsheet-low-carbon-heat-scheme

[7] The Guardian, UK installations of heat pumps 10 times lower than in France, report finds – https://www.theguardian.com/environment/2023/jul/17/uk-installation-heat-pumps-report

[8] The Independent, Octopus unveils product to ‘end the world of ugly heat pumps’ – https://www.independent.co.uk/business/octopus-unveils-product-to-end-the-world-of-ugly-heat-pumps-b2411666.html

[9] IEA, Buildings – https://www.iea.org/energy-system/buildings