Published by Jacob Newton, Senior Commercial Manager for Air Source Heat Pumps | Hive
Air source heat pumps work by transferring warmth from the air outside into your home. So lots of people wonder how they can possibly work in winter – just when you need hot water and heating the most!
The short answer is that there’s still more than enough heat in the air during cold weather to keep things warm and comfortable inside. Which explains why heat pumps are so popular in Scandinavian countries like Norway!
In this article we’ll explain everything you need to know about how heat pumps work in cold weather. Plus, we’ll hear from Gav – one of the Hive team who’s had a heat pump in Scotland for six years.
Do heat pumps work in the winter?
Heat pumps work brilliantly in the winter, keeping your home supplied with plenty of hot water and heating – even when temperatures plummet to -15°C or lower.
How? Heat pumps absorb warmth from the air using a cold liquid refrigerant. This boils and becomes a gas at a very low temperature (usually about -20°C).
So even when it’s -15°C outside, the refrigerant will still be colder than the air. And that heat difference makes it possible to transfer heat from the air to keep your home cosy.
What’s your advice to homeowners worried about comfort in very cold weather?
“I’ve had a heat pump for 6 years now – and I’ve never had a problem in my home with heating or hot water in winter. The weather can get pretty fresh here in Scotland, so I’d take that as a positive endorsement!”
Gav Murray, Director of Heating, Hive
Performance of any heating system is dependent on various factors including property insulation, installation and weather conditions.
How efficient is a heat pump in cold weather?
Heat pumps are less efficient during the winter than in the summer, but they still provide a lot of heat for the amount of energy they use.
The efficiency of a heat pump is measured by COP, which stands for Coefficient of Performance. The COP tells you how much heat is produced per unit of electricity.
For example, a heat pump might reach a COP of 4.0 in the summer, which is an efficiency level of 400%. That means you get up to an impressive 4 units of heat for every unit of electricity that’s used.
But when temperatures drop to 0°C, the heat pump needs more electricity to reach the right temperature. The COP will typically decrease to around 2.5 (or 250% efficiency) – which is still 2 or 3 times more efficient than an A-rated gas boiler.
At what temperature do you typically see a drop in heat pump efficiency?
“To be honest, it's not something that I pay much attention to. Like with any heating system in the colder months, you know you’re going to be asking more of it in the winter than the summer. A heat pump isn't really any different in that respect. I ask it to ensure my heating and hot water is ready in line with my comfort levels – and it does the rest.”
Gav Murray, Director of Heating, Hive
How can I find out how efficient my heat pump is?
You’ll find your heat pump’s COP rating in its documentation. But bear in mind that this is a score achieved in specific test conditions. In reality, your heat pump’s COP will vary quite a bit depending on the outside temperature.
Luckily, there is a measure that can help you make sense of this variability. Look for your heat pump’s Seasonal Performance Factor (SPF) or Seasonal Coefficient of Performance (SCOP). This number gives you an average across the whole year.
What can you do to protect your heat pump in the winter?
Heat pumps are designed to be outside, all year round – so they’re capable of withstanding whatever challenges winter might bring. Having said which, there are a few things you can do to help your heat pump maintain performance all year round.
Book regular services
An annual service is important for keeping your heat pump working effectively. We recommend scheduling one every year, ideally before the cold weather begins. Book with British Gas and one of their engineers will visit your home to check refrigerant levels and make sure everything is working as it should be.
Keep the area clear
Leaves in autumn, snow in winter – anything that can build up and prevent free airflow around your unit will ultimately affect its performance and efficiency. Snow spacers are often included for installations in countries with heavy snowfall, but they’re rarely needed in the UK. We recommend checking your heat pump every now and then to make sure nothing is blocking the area.
Don’t cover your heat pump
Your heat pump is designed to operate in all temperatures. It doesn’t need to be covered to protect it from the winter – and in fact, you could end up damaging the unit if you do put anything over it.
Never try to remove ice
The automatic defrost function on a heat pump should deal with any ice build-up. Trying to remove it yourself could cause damage to its parts. If you are concerned that there is excessive ice on your heat pump, it could be a sign of a problem – so call out an engineer to take an expert look at what’s going on.
Do you need to look after your heat pump in the winter?
“Not really. The beauty of a heat pump is it’s very much ‘set and forget’. For example, when I had it installed, I was advised not to interact with it like you would with a boiler’s thermostat. I just set a desired temperature and that’s maintained throughout the year. Obviously, the heat pump works harder in the winter, but there’s nothing I need to do myself.”
Gav Murray, Director of Heating, Hive
Do ground source heat pumps work in winter?
Wintry conditions don’t affect the efficiency of ground source heat pumps in the same way as air source heat pumps. That’s because underground temperatures are relatively stable throughout the year – usually between 8°C and 12°C in the UK.
So a ground source heat pump might be worth considering if you live in a particularly cold area, if you have a large garden where ground loops can be installed – and if you’re prepared for a more a more complex and expensive installation process.
Find out more about ground source heat pumps
When should you use back-up heating options?
In Scandinavian countries, it’s common for heat pumps to have a fossil fuel back-up for times when temperatures drop below -20°C. However, this is rarely necessary in the UK because heat pumps are designed to work perfectly, even in our coldest weather.
But if you are interested in a back-up solution, it’s always possible to add immersion heaters, electric heaters or even gas boilers to your heating system. Or you can install a hybrid heat pump, which combines an air source heat pump with a gas or oil boiler in the same unit.
How much does it cost to run a heat pump in winter?
As with any heating system, the actual cost will depend on a range of factors – including the size of your property, the quality of your insulation, and the level to which you heat your home.
The Energy Saving Trust has calculated that someone switching from a G-rated boiler to a heat pump could save £260 a year. And someone switching to a heat pump from an electric storage heater could save £700 to £1,200 a year.
How have you found the cost of running a heat pump?
“I live in a large house in Scotland. Last year my heat pump used about 5270 kWh of electricity. I’ve opted for a Time of Use tariff because I’ve got an EV charger, solar panels and a battery. My heat pump makes hot water overnight at a cheap rate, and I also charge my battery then. I use the stored energy to run the heat pump whenever possible. All this has helped me cut my costs by around 34% over the last year.”
Gav Murray, Director of Heating, Hive
Savings may vary.
What are the best air source heat pumps for cold climates?
Hive arranges installs for a range of industry-leading heat pumps that can deal with any weather conditions typically experienced in the UK. Expert installation teams will ensure your heat pump performs efficiently, even in freezing weather.
Want to find out more? Get in touch for a free home survey and no-obligation quote today.
Get a heat pump quote
Frequently asked questions
Can heat pumps freeze in the winter?
No, heat pumps are designed to be outside in all weather conditions, so don’t worry about them freezing. All Hive heat pumps have automatic defrost cycles that temporarily reverse the airflow, melting any ice that build up on the coils. It’s a good idea to clear away any snow that builds up – but never try to remove ice yourself, as you might just end up damaging the heat pump unit.
Should you defrost a heat pump?
No, heat pumps defrost themselves automatically when sensors detect any ice build-up. However, if you do notice frequent icing, book an engineer to take a look. It could be a sign that there’s a problem that needs some expert attention.
Learn more about heat pumps
1: £0.263/kWh for electricity is based on the October 2025 price cap – please note this will fluctuate over time.