Wait, heat pumps can cool down houses as well as heat them? Experts explain how they could be a better option than air con

We're all having to come to terms with the fact that swelteringly hot summers are no longer an anomaly here in the UK – in fact, they are fast becoming the norm with hot-weather records seemingly being broken again and again. While we may have all once wished for long, sunny summers, it seems we were totally under-prepared for the reality of living in homes that just weren't designed with these in mind.

What all of this means is that, rather than simply focusing on ensuring their properties are prepared for winter, homeowners these days are desperately seeking ways to keep a house cool.

While there are lots of clever hacks out there which can be really effective when it comes to dealing with heat in the short-term, it is important that we all start looking into more permanent solutions – heat pumps being one of them. If you didn't yet know, having one fitted could just be the solution you have been after when it comes to keeping your home fresh and cool, as the experts I spoke to explained.

Can you use a heat pump to cool a house?

Before getting into whether or not a heat pump can cool a house down, it is worth mentioning that there are two types of heat pump: air-source heat pumps and ground-source heat pumps. On very a basic level, the former takes heat from the air outside your house to heat your home, while the latter takes it from the ground. However, within both categories, there are several different types of system (air-to-air and air-to-water heat pumps, for example) that work quite differently so make sure you do your research first.

That said, both types can be used to cool a house, as Mark Parker, senior mechanical design engineer at Elite Renewables, explains. 'Not all heat pumps can provide cooling, but many air-source and ground-source heat pumps can if they are designed for reversible operation.

'Air-to-air heat pumps, which are essentially air conditioning systems with a heating function, are naturally suited to both heating and cooling. Air-to-water heat pumps can also provide cooling when paired with compatible emitters and controls,' adds Mark.

Mark Parker

Mark Parker is a Senior Mechanical Design Engineer at Elite Renewables, specialising in low carbon heating, cooling and ventilation systems for residential and commercial developments. With extensive experience designing heat pump, HVAC, MVHR and underfloor heating systems, he works closely with architects, developers and installers to deliver practical, energy efficient building services solutions.

How do air-source heat pumps cool a house?

Air-source heat pumps are both cheaper and easier to install than ground-source which is why they are often the preferred option for homeowners, particularly when retrofitting. But are they good for cooling a house?

Interestingly, there is little to no difference between some air-source heat pumps and air conditioning, as Adam Wilson, head of delivery at Furbnow, explains. 'People don’t realise that when they buy air conditioning, they’re really buying a heat pump. An air-to-air heat pump is essentially air conditioning, and air conditioning is essentially an air-to-air heat pump. The difference is that an air-to-air heat pump can cool and also heat.'

As we've mentioned air-to-air heat pumps are just one type of air-source heat pump – so what about air-to-water systems?

'Air-to-water heat pumps provide cooling by circulating chilled water through compatible emitters, such as fan coil units or, in some cases, underfloor systems,' explains Mark Parker. 'The cooling effect is typically gentler and more gradual, making it better suited to maintaining a comfortable indoor temperature rather than delivering an immediate blast of cold air.'

'Air-to-water systems can provide cooling, but the heating system must be designed for it,' points out Adam Wilson. 'The radiators or underfloor heating need to be designed to cool as well. You can have radiators with small fans built into them. The heat pump provides cold water and the fan distributes cooler air around the property.

'With underfloor heating, you can switch it to a cold mode, where the underfloor heating becomes a cooling system,' continues Adam. 'However, this remains less common in UK homes. People aren’t as aware of the technology, and the supply chain of people who install those systems is limited.'

Adam Wilson

Adam Wilson is Head of Delivery at Furbnow, helping homeowners plan and manage energy upgrades alongside wider renovation work. He assesses each property, recommends the right mix of improvements, and creates a clear plan before builders begin. This helps homeowners avoid costly mistakes and make their homes warmer in winter, cooler in summer and cheaper to run.

Can ground-source heat pumps cool a house?

While ground source heat pumps are still not as common as air-source systems, they are still a great option when it comes to cooling a house.

'Ground-source heat pumps can be particularly effective because the ground remains relatively cool throughout the summer,' explains Mark Parker. 'This allows some systems to provide highly efficient passive cooling while using very little energy.

'Ground-source systems can also use the heat removed from the property to recharge the boreholes or provide hot water, making them an extremely efficient option.'

Are heat pumps as effective as air conditioning?

While there is really isn't much difference between some air-to-air heat pumps and air conditioning, there are some pros and cons of each to be aware of if you are trying to decide whether air conditioning is worth it or choose between the two.

'Which is best for you depends on what you are trying to achieve,' picks up Mark Parker. 'If you want rapid cooling in individual rooms during a heatwave, a dedicated air conditioning system is generally the better option. However, if you are looking for year-round heating with the added benefit of gentle cooling, a reversible heat pump can be an excellent solution. It will not always match the cooling performance of air conditioning, but it offers greater versatility.'

Of course fixed air con is one thing – but how do the best portable air conditioning units compare to heat pumps?

'The standalone units people buy, plug in and put a duct outside are very different,' explains Adam Wilson. 'That’s a cooling-only air-conditioning unit. When people have a modern air con system installed, they are essentially buying an air-to-air heat pump. Unlike portable air-conditioning units, an installed air-to-air system normally has an outdoor unit connected to indoor wall units. These are generally fitted higher on the wall because that’s where you get the most circulation in a room.'

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How do you maximise a heat pump's cooling effect?

If you do decide a heat pump is right for your home and plan on using it as a method of cooling it down, you want to be sure you are spending your money wisely.

'The system must be properly designed and sized,' advises Adam Wilson. 'Air-to-air heat pumps need to follow the same process as air-to-water systems. They need room-by-room heat-loss calculations before they are installed, so that they are designed properly.

'Homeowners should also prevent excess heat from entering in the first place,' adds Adam. 'Make sure the walls are well insulated and look into loft insulation, avoid too much glazing, and consider window shutter ideas (including external shutters), and passive cooling.'

That said, Becky Lane, co-founder and CEO of Furbnow, is keen to point out that heat pumps are not just for airtight new builds. 'It’s a myth that your home has to be perfectly insulated for a heat pump to work. But if your home loses cold air easily, you’ll need a bigger, more expensive heat pump, which can be louder, less efficient or comfortable and may not save you that much money.'

Becky Lane

Becky Lane is the co-founder and CEO of Furbnow, leading the company cutting through the home energy upgrade chaos with clear plans, simple tech and real experts. With more than 15 years’ experience in home energy, Becky has led major programmes that changed how the UK approaches improving its homes. As a qualified Retrofit Coordinator, she brings both technical insight and hands-on experience from working with households, councils and industry.

What type of heat pump is best for year-round comfort?

For most people, the ideal set up is to install a system that will both heat and cool their home as and when needed, in an efficient way that also doesn't visually intrude on their overall interior scheme. It is important to understand the disadvantages of air-source heat pumps too. So what kind of system did they experts say would be best for achieving this?

'For most homeowners, a reversible air-to-water heat pump paired with underfloor heating and fan coil units offers an excellent balance of efficient heating in winter and comfortable cooling in summer,' advises Mark Parker. 'Or, where budgets allow and the property is suitable, a ground-source heat pump can deliver even greater efficiency, along with the added benefit of low-energy passive cooling. The best solution ultimately depends on the property’s design, insulation levels and the homeowner’s expectations for cooling performance.'

'For heating alone, air-to-water heat pumps are the most common choice in the UK. They replace your boiler, connect to radiators or underfloor heating, and heat your hot water too. They suit most homes where there is already a wet heating system in place,' picks up Becky Lane. 'However, you may also need new radiators and pipework, which can mean lifting floors or working behind kitchen units. Air-to-air systems can be less disruptive to install than air-to-water and suit homes without radiators, flats, properties with storage heaters, single rooms, loft conversions or garden rooms, and homes where overheating is a concern.'

Adam Wilson agrees. 'You don’t have all the pipework to change as the units sit on the wall, with two small pipes running externally to the outdoor unit and an electricity supply. In terms of internal disruption, it is minimal compared with an air-to-water system.'

FAQs

Is air conditioning cheaper than a heat pump?

One of the main driving factors when deciding whether or not to install a heat pump in order to cool your home is likely to be heat pump costs, both in terms of installation as well as day-to-day running.

Stephen Evans, founder of Costwise, shines a light on the differences between air-source heat pumps and air conditioning costs. 'An air-source heat pump runs £7,000 to £20,000 installed, typically £13,000, and the Boiler Upgrade Scheme takes £7,500 off that, so roughly £5,500 net. But, that spend is a heating investment. Cooling, on the systems that offer it, is a bonus rather than the reason you buy one. A dedicated air conditioning unit will be £1,500 to £7,000 supplied and fitted, typically £2,800.

'So, if you're asking which is the best investment for year-round comfort, the honest cost-based answer is a heat pump,' continues Stephen Evans. 'It earns its money as a heating system with the grant behind it. If cooling is the priority, however, air con does that job for well under half the net cost. Spending £13,000 on a heat pump, mainly to cool a house, is poor value, when £2,800 of air con could do the job.'

Stephen Evans

Stephen Evans is founder of Costwise UK, a site that collects price data of 150+ UK home renovation services.

While ground source heat pumps are a fantastic investment and can work well to both heat a house as well as cool it, it is important to familiarise yourself with the disadvantages of ground source heat pumps too. They are more expensive than air source systems and tend to be a little more disruptive to install.