Eco Heat Pumps

Getting a heat pump is a big investment, which will save a lot of energy. Switching homes from gas boilers to heat pumps is set to play a significant role in meeting the UK’s targets to reduce emissions, as well as saving home energy costs in the long run.

This guide to environmentally friendly heat pumps explains the basics of how heat pumps work and gives a rough guide to heat pump costs. It discusses how heat pumps compare to gas boilers in terms of emissions and efficiency, and what progress the UK is making in terms of acceptance and installations.

Who's in the guide to heat pumps?

We cover 21 manufacturers of heat pumps (with a total of 23 brands) in this guide, revealing how the different companies score for their tax conduct, directors’ pay, treatment of workers in their supply chain, and climate reporting. 

Most of the heat pump brands make air and ground source heat pumps. We have specified later in the guide who makes what, with one brand making hybrid heat pumps. 

This guide covers more well-known manufacturers such as Baxi, Vaillant, Viessmann, and Worcester Bosch, along with other brands like Daikin, Grant, Kensa and Nibe, some European brands like Aira and big names like Mitsubishi and Samsung.

With overall ethical scores ranging from 5 to almost 60 (out of 100), there's scope to find a more ethical brand of heat pump.

How do heat pumps work?

Technologically, heat pumps are like fridges in reverse. Like a fridge, they use a refrigerant, which is a liquid that can absorb heat and then transfer it. But, instead of taking the heat from inside and transferring it outside, they can take heat from outside – either from the air or from the ground, even when it feels cold – and transfer it into your house.

Heat pumps are astoundingly efficient, delivering about three units of heat for each unit of electricity needed to run them.

If the outside is colder, they have to work harder but are still very efficient. As heat pumps generally heat water to a lower temperature than a gas boiler (though higher-temperature pumps now exist), the idea is to use them for longer periods, and have more surface area to distribute the heat, such as triple panel radiators, or underfloor heating.

The main types of heat pump are air source (air to water), ground source, and hybrid, which all heat water.

Different types of heat pumps

Heat pumps are a substantial investment, so it’s important to make sure you get the right one for your house. There are different types of heat pumps, with different costs and installation factors.

Air source heat pumps: air to water

Most of the heat pumps installed in the UK are air to water, as they don’t require much space. They provide both water and space heating. They can be installed on almost all properties, including flats. They are generally about the size of a fridge and require a place outside where they can be fitted to a wall or on the ground, with space for a good flow of air around them.

All air source heat pumps do produce some noise, as they contain a fan and compressor, but the modern ones are much quieter: about 40 to 60 decibels, which is a similar noise level to a fridge or dishwasher and therefore rarely a problem.

Air source heat pumps: air to air

Air to air heat pumps are just air conditioners that have been put into reverse. They blow hot air into your house, so they only do space heating. You would need something else for hot water. Air to air pumps do have some advantages. The pumps are cheaper and have good efficiency. Since they don’t use radiators, you won’t need to install bigger ones, although you may need ducting (pipes) in order to carry the hot air around to different rooms.

Ground source heat pumps

Ground source heat pumps take heat from the ground instead of the air, using pipes buried outside the house. This makes them much more efficient, and silent. However, they are more expensive and only suitable for a limited number of homes because they require considerable amounts of outside space.

Horizontal ground source heat pumps need pipes that are buried in a long trench in your garden, about a metre deep. You’ll need an area about twice the size of your home. Vertical ones have pipes in a series of boreholes instead – down to 70 or 100 metres. This means they require much less garden space. But they are far more expensive to install, and you will need space for the drilling machinery.

Hybrid heat pumps

Hybrid systems combine a heat pump and a traditional boiler. The theory is that the heat pump does most of the work, but the boiler helps out if necessary. This could be if you have a larger home and only single phase electricity, or were not able to increase insulation to reduce heat demand.

A hybrid system can be cheaper to install if you already have a boiler and are just installing a heat pump to work alongside it, because you may get away with a lower capacity heat pump and not replacing your radiators. However, it might not be cheaper over the lifetime of the heat pump, and the current grants are not available for hybrid heat pumps systems. The energy savings will also be less as the boiler is still being used. 

Which brands make which types of heat pumps?

Most brands of heat pumps in this guide make both air source and ground source heat pumps, but some only make one type. 

The table below shows you which brands make what type of heat pump.

How much does a heat pump cost?

The table below, taken from the Energy Saving Trust, will give you a rough idea of costs. An installation may cost less than the figures here, as they are based on a 3-bedroom semi, with radiator upgrades as needed.

As well as the Boiler Upgrade Scheme (BUS) grants of £7,500 (or more in rural Scotland), there are even some green retrofit mortgages available from some mortgage providers – either special rates for additional borrowing or cashback deals up to £2000. 

Installation costs can vary a lot, mostly depending on the heating needs of your household, which are determined by the size of house, how “heat pump ready”’ it is (e.g. levels of insulation and size of radiators), number of people, and usage habits. A heat pump can last 10-20 years or more if well maintained.

The savings on running costs you could make vary a lot too, depending on what energy source you are switching from, how efficient your heat pump is, and how well it is set up, and the changing price of electricity and gas. At current electricity prices, not all heat pump installations will result in lower bills.

The Climate Change Committee (CCC, the official body that advises the UK government on decarbonisation) recommends the government shift the costs of renewable energy subsidies – which are currently included in the cost of electricity – to general taxation.

This would make running heat pumps relatively more attractive. For now, you may be able to get cheaper electricity on a heat pump tariff from some energy suppliers. Both Good Energy and Octopus Energy offer heat pump tariffs.

As all these figures are so variable, we have not included an estimate of payback time, but you can explore more about costs with the interactive calculator on the Which? website.
 

*Potential annual savings: Not including switching from an A-rated gas boiler or from oil boilers, where bills would currently cost more. Figures are for a 3-bedroom semi-detached home in England, Scotland, or Wales, with radiator upgrades as needed. Based on fuel prices in July 2025.

How do heat pumps compare to gas boilers?

According to Friends of the Earth, heat pumps can reduce your carbon footprint from heating by up to 80%.

Compared to the most efficient gas boilers currently available, a heat pump will save on average over 1.5 tons CO2 per year. That’s big, considering that the annual carbon footprint for someone in the UK is, on average, 12 tonnes per year.

If you live in one of the million homes in Britain using an oil boiler, the carbon savings could be much higher.

And even if you aren’t planning to get a heat pump, it’s valuable to find out about them because pretty much every route to avoiding climate meltdown includes heat pumps playing a significant role.

The International Energy Agency (IEA) says that heat pumps currently meet around 10% of the global heating need in buildings. According to its Net Zero Emissions by 2050 scenario, they need to meet 20% of the need by 2030 and over 50% by 2050.

The Climate Change Committee's suggested pathway to net-zero sees the majority of UK homes being heated with heat pumps by 2040. 

In our annual Climate Gap report, heat pump installations in the UK are one of the things we are tracking, and a big jump is required to meet the CCC target for 2030.

Should I get a heat pump?

In our list of the highest carbon savings consumers can make, installing a heat pump comes in at number 3, after reducing long haul flights and reducing meat and dairy consumption.

If you’re worried about money, a heat pump may not turn out to be an investment you can make, but it's still worth checking for your particular situation. See the costs section above.

If you can definitely afford the initial investment, any potential upgrades to insulation and radiators, and are able to risk potentially spending a bit more on your energy bills in the next couple of years in order to cut carbon, then the answer is 100% yes – buy a heat pump.

It is one of the best things you can do to cut emissions and help the transition to renewables.

How efficient are heat pumps?

There are several acronyms, figures and labels you may see to describe the efficiency of a heat pump system, which we'll explain below. Because the efficiency depends on much more than the energy label of the pump, we have not listed the labels of different models here.

Heat pump energy labels

Heat pumps are assigned a class (A+++ to G) based on their SCOP. The label also indicates the pump’s noise emission levels, measured in decibels.

Is Seasonal Performance Factor (SPF) the new SCOP?

The most commonly seen measure of the efficiency of the heat pump itself is its SCOP, which stands for Seasonal Coefficient of Performance.

It is a figure from the manufacturer to show the heat pump’s efficiency averaged across the whole year, and ranges from between two and five, the higher figure being better. It aims to show how many units of heat you’ll get out per unit of energy you put in and may be expressed as a ratio, e.g. 4:1 or a percentage, in this case, 400% efficient.

But, since March 2025, MCS-certified installers are required to provide instead an SPF figure, also expressed as a ratio. The MCS (Microgeneration Certification Scheme) is the UK body which defines and maintains the Standards for low-carbon energy technology products, contractors, and their installations. 

This SPF, or “Seasonal Performance Factor” is more tailored to your particular situation, using data from your EPC, your location, weather data, and what “emitters” are used, such as radiators or underfloor heating. Your EPC is the Energy Performance Certificate, which shows the energy efficiency of your home.

However, an installer may well be able to achieve a higher level of efficiency from the way they install and set up the system. As part of their assessment of your house, an installer should do a heat loss survey and be aiming to design for a low flow temperature (the temperature the water is heated to) to make the system more efficient. You can ask them what system temperature they are aiming for, and how this can be measured after installation.

The HeatGeek network, which provides training to independent installers, are so confident they can make a heat pump work efficiently in any situation that they provide a guarantee for any installation contracted through them. They have a series of consumer videos on YouTube. 

Challenging misinformation about heat pumps

The government has contracted the consultancy firm, the Behavioural Insights Team (BIT), to challenge myths and misinformation about heat pumps that are hampering uptake of the technology.

According to the contract between the firm and the Department for Energy Security and Net Zero, the media is sharing negative stories about heat pumps, saying that they are overly noisy, too expensive to install, unreliable, and unable to work in older buildings. BIT has been awarded £100,000 to push back against this misinformation.

A 2023 investigation by DeSmog found that the Energy and Utilities Alliance (EUA), a trade body representing boiler manufacturers and others involved in the commercial heating sector, had paid the PR firm WPR to generate negative news stories about heat pumps. These had featured in outlets such as The Sun, Telegraph, and The Express and were designed to “spark outrage” about heat pumps, according to the WPR website. 

Manufacturers who are members of the EUA

Not surprisingly, almost half the brands in our boilers guide appear on the EUA’s list of members at the time of writing. And some of these brands are in our Recommended lists because of their relatively high scores elsewhere. Consumers concerned about climate change might want to choose a company not engaged in supporting a misinformation strategy around this most important of technologies.

EUA members in boilers guide: 
Advance Appliances, Alpha, Baxi, Electric Heating Company, Heatrae Sadia, Ideal, Intergas, Vaillant, Viessmann, Worcester Bosch

EUA members in this heat pumps guide:
Alpha, Baxi, Danfoss, Dimplex, Grant, Ideal, Intergas, Vaillant, Viessmann, and Worcester Bosch.

EUA members in solar panels guide: 
Viessman

EUA members in energy suppliers guide:
British Gas

What is it like to have a heat pump?

Mike Childs, Head of Science, Policy and Research at Friends of the Earth says,

“I got an air-source heat pump and it’s kept our home warm, including through a cold North-of-England winter.

It extracts heat from the air outside, even when it’s freezing cold, and uses it to heat the water in our radiators and in our hot water tank. It doesn’t make the water as hot as a gas-fired boiler, so to ensure our house is warm enough it runs for longer and we’ve increased the size of our radiators. The heat pump itself is in our backyard where it hums away quietly.”

One of our readers Alison said, “As I'm not in the house much, I chose an air-to-air heat pump (aka air-conditioning run in heating mode) as it’s fast to heat rooms when needed and a bit more efficient (higher COP) than air-to-water. I put in an electric hot water cylinder for my water heating. The setup works well for someone not at home much and is cheaper to run than I'd feared. It can also cool in heatwaves if needed.”

Progress of heat pump installations in the UK

Heat pumps are still rare in the UK although they are gaining popularity.

About 98,000 heat pumps were installed in 2024, compared to 55,000 in 2022.

However, they still make up only 4% of new heating systems installed in the UK, compared to 30% in Ireland and 31% in the Netherlands, and there is still a shortage of heat pump installers.

The new Future Homes Standard legislation for England (and similar legislation in Northern Ireland, Scotland, and Wales) should help, as it will apply to all new-build homes and should triple the size of the heat pump market, leading to economies of scale and the confidence needed for the sector to grow. It is expected to be published in Autumn 2025, and become law about a year later, ending the installation of fossil-fuel boilers in new-build homes. 

How do heat pump companies rate on ethical and environmental issues?

Our ratings look at a variety of ethical and environmental issues to see how companies perform. Here we highlight how heat pump brands rate for climate actions, workers' rights, tax conduct, excessive pay at the top, and involvement in controversial sectors. 

Climate 

Given that this is a guide to heat pumps, a low-carbon technology, companies’ scores for their climate action weren’t that high, with more than half of the brands scoring below 50 for this rating (out of 100).

We look for companies to have identified and reduced their main carbon impacts, and also give marks if companies report their emissions and have a reduction target in line with international agreements. Companies also get marks if their whole business has a significant focus on low-carbon products.

The following companies scored the highest marks (60/100): 

• Danfoss
• Nibe (which owns CTC and Nibe brands)
• Octopus
• Robert Bosch (which owns Hitachi Yutaki and Worcester Bosch brands)
• Viessmann 

Danfoss and Robert Bosch provided evidence of having reduced their impacts and the others had a significant focus on low-carbon products.

The following companies also got marks for being almost wholly focused on low-carbon products: 

• Aira
• Kensa
• Stiebel Eltron

Workers rights 

MasterTherm scored highest with 60 points as a small company (turnover under £50m) that manufactured its products in-house. We reward this as it means that companies are not outsourcing the manufacture of their products to third-party companies where they have less oversight of working conditions and less direct responsibility for their workers.

Kensa also manufactured in-house, in Cornwall, but is majority-owned by Octopus Group so was rated as a large company which resulted in a lower score.

Other large companies that appeared to manufacture the majority of products in house were Alpha, Bosch, Daikin, Danfoss, Dimplex, LG, Stiebel Eltron, and Mitsubishi.

Eight companies in total lost marks for criticisms by third parties of their practices on workers’ rights: 

• Daikin
• Glen Dimplex
• LG
• Mitsubishi
• Octopus
• Panasonic
• Paloma (Intergas)
• Robert Bosch (Hitachi Yutaki and Worcester Bosch).

In 2024, Daikin and Panasonic were both named as buyers from the Kawaguchi factory in Malaysia where human rights abuses including wage theft, recruitment fee charging, and intimidation were reported.

Tax conduct

Nine companies got top marks for the tax conduct rating as they had no subsidiaries in tax havens. These were:

• Aira
• Immergas (Alpha)
• Baxi
• Danfoss
• Grant
• Intergas
• MasterTherm
• Stiebel Eltron
• Vaillant

Ideal and LG scored 20 (out of 100) as they each had one subsidiary in a tax haven.

The rest – more than half the companies in the guide – scored 0 as they either had an ultimate parent company that was registered in a tax haven or they had at least two subsidiaries in tax havens.

Excessive directors’ pay

Only three companies lost marks for excessive directors’ pay (over £1m in the most recently reported year). These were Carrier (Viessmann), Mitsubishi, and Panasonic.

However, many more large companies did not appear to disclose pay details so were also marked down for lack of transparency: Aira, Bosch, Daikin, Danfoss, Dimplex, Groupe Atlantic (Ideal), Immergas (Alpha), LG, Octopus, Paloma (Intergas), Remeha (Baxi), Samsung, Stiebel Eltron, and Vaillant.

In fact, the only other companies that disclosed director pay did not have any director paid over £1m. They were Nibe, and the smaller company Grant Engineering. Kensa also did not pay over £1m but its majority owner Octopus lost marks for lack of transparency. The other smaller company MasterTherm did not disclose details.

Involvement with controversial sectors

The following companies lost marks for involvement in controversial sectors:

• Danfoss, Immergas (Alpha), and Paloma (Intergas) were involved in fossil fuels.
• Daikin, Mitsubishi, Panasonic, and Samsung were involved in arms and military supply.
• Mitsubishi was also involved in nuclear energy.

Additional research by Shanta Bhavnani.