Do heat pumps work in winter and cold weather?

If you’re considering or have recently made the switch to a heat pump, you’ll probably be wondering how well it will work in the winter. After all, the colder months are when your heating system is most needed, and you want to ensure you stay warm no matter the outside temperature.

In this guide, we’ll answer all of your burning questions about heat pump efficiency in cold weather. For a broader look at heat pumps, see our expert heat pump guide.

How do heat pumps work in winter?

Before understanding how heat pumps work in winter, we first need to understand how they work in general.

Heat pumps extract energy from the air using substances called refrigerants that have very low boiling points. As air passes through the heat pump, energy is transferred to the refrigerant, causing it to boil and become a gas. It’s then compressed to increase the energy and temperature even further, and this energy is transferred to the water that flows around the heating system.

But how does a heat pump work when the weather outside is cold?

It’s a common misconception that in winter, there's no heat in the outside air for your heat pump to warm your home. However, the refrigerant liquid is so heat-sensitive that even very small amounts of heat in the air (and air always contains at least some heat) are enough to boil it.

To check whether your property setup is optimised for this process, read our advice on ’Should I install a heat pump in my home?’.

Heat pump efficiency in cold weather

One of the greatest advantages of a heat pump is its efficiency, often 300-400%. This means that the heat energy produced is three to four times more than the electrical energy input.

As mentioned above, winter means that there isn’t quite as much heat energy in the air, which decreases a heat pump’s efficiency. However, the efficiency of an air source heat pump in winter remains higher than that of a boiler. See our guide to heat pumps vs. gas boilers to further explore the differences between the two.

To understand heat pump efficiency in cold weather, you will need to look at your pump’s SCOP. SCOP stands for Seasonal Coefficient of Performance and measures how your heat pump performs year-round, including in the colder months. This accounts for slightly lower efficiency in winter.

Outdoor Temperature	Heat Pump Performance	What Happens Inside the Unit?
7°C to 12°C (Mild Winter)	Peak Efficiency (COP 4.0+)	Operates effortlessly at low flow temperatures
2°C to 7°C (UK Winter Average)	High Efficiency (COP 3.0–3.5)	Weather compensation adjusts output automatically
0°C to -5°C (Freezing)	Efficient Heating (COP 2.0–2.5)	Automatic defrost cycle runs briefly to clear coil frost
Down to -20°C (Extreme Cold)	Guaranteed Operation	System continues to extract ambient heat from outside air

How to maximise air source heat pump efficiency in winter

Follow our tips to ensure your heat pump works as efficiently as possible in winter.

1. Schedule heat pump servicing before winter

Winter is when you need heating the most, so book your servicing with an engineer in summer or autumn to ensure your heat pump is in optimum working condition.

See our blog on what to expect from a heat pump servicing to understand more about this process.

2. Keep your thermostat at a set level

We know that on those chilly days, you want to turn the thermostat right up - but it’s important you resist the urge. Heat pumps are most efficient when operating at a consistent level, as a sudden increase forces them to work harder than expected.

Of course, if you’re really chilly, you can turn your thermostat up; just avoid lots of sudden up-and-down changes. Ideal heat pumps have weather-compensating controls, which means the heat pump already knows to work that little bit harder in the cold and to ease off in the milder months.

3. Remove airflow restrictions

Because the air's heat content is low in winter, your heat pump needs to draw in a large volume of air to collect enough heat without overexerting itself. A lack of airflow can also cause your heat pump to frost up in winter, as it can make the evaporator colder than the surrounding air.

You can prevent this by making sure there are no objects in front of your heat pump and by removing leaves and debris from the back for optimal airflow.

We also advise against using a heat pump cover unless absolutely necessary. This can significantly restrict your heat pump’s airflow.

For a broader look at cold-weather management, read our complete tips on how to heat your home efficiently in winter.

What is the lowest temperature a heat pump can work at?

While the lowest temperatures at which heat pumps can operate vary, almost every air source heat pump can work at sub-zero temperatures, often at least -15C, making them well equipped for British winters, which average 2-7C.

If you’re still unsure about how well a heat pump can handle cold climates, over two-thirds of Norway’s homes use heat pumps, and the winters there are an average of -6.8 °C.

At Ideal Heating, our Logic Air heat pumps work effectively down to -20 degrees.

Will running my heat pump cost more in winter?

Because heat pump efficiency is lower in cold weather, your heat pump will use more electricity to operate, increasing your home's energy costs. However, heat pumps remain highly efficient in winter and will produce more heat energy than the electrical energy they consume. See our guide to heat pump costs for more information.

Finding the Right Heat Pump System for Your Home

Choosing a low-carbon heating system is a significant decision, but it brings long-term efficiency, lower carbon emissions, and peace of mind. Ideal Heating supports your green transition with over a century of British engineering expertise.

Explore our low-carbon technology options to find the right fit for your property: