As the UK moves towards cleaner, greener energy solutions, heat pumps are becoming a hot topic for homeowners, landlords, and commercial property owners alike. But a common question still lingers: how does a heat pump work in winter, when it’s freezing outside?
Understanding how heat pumps operate in cold conditions is essential for making an informed decision about heating upgrades.
This guide is for UK homeowners looking to cut energy bills, landlords seeking EPC compliance, and commercial businesses focused on sustainability goals. We’ll explain how modern heat pumps continue to deliver reliable heating in winter, how they compare to traditional systems, and why now might be the best time to make the switch.
Do Heat Pumps Work in Winter in the UK?
In short, yes. Heat pumps work on the principle of transferring heat rather than generating it. Even in winter, outdoor air contains thermal energy. Air source heat pumps (ASHPs) extract this energy and use it to warm your indoor space.
Even at temperatures as low as -15°C, the air contains heat energy. A heat pump uses a refrigerant cycle, compressing and expanding fluid to absorb outdoor heat and release it indoors.
Key Components Involved:
- Evaporator Coil: Absorbs heat from outside air.
- Compressor: Increases the temperature of the refrigerant.
- Condenser Coil: Releases heat indoors.
- Expansion Valve: Regulates refrigerant flow back to the evaporator.
Do heat pumps work less efficiently in cold weather?
Yes, but not drastically. The Coefficient of Performance (CoP) of a heat pump typically drops as temperatures fall. However, modern systems still achieve CoPs of 2.5–3.0, even around 0°C, meaning that for every unit of electricity, you get 2.5–3 units of heat.
Thanks to advances in low-temperature heat pump technology, these systems can extract enough heat from the outside air, even in sub-zero conditions, to keep your home or building warm. Proper installation and insulation further enhance their performance during winter.
If you’re based in Tyne and Wear, Newcastle, or the North East, you can request a free heat pump installation quote from Future Heat, your local MCS-certified experts in energy-efficient heating.
What’s the lowest temperature a heat pump can handle?
High-quality air source heat pumps can operate effectively in temperatures down to -20°C, which exceeds the coldest UK averages.
What about snow, ice, and frost?
Modern systems come with defrost cycles to prevent icing on coils. Regular maintenance and proper installation ensure that your heat pump performs reliably through winter.
For air source heat pumps installed in older houses, it is still possible for them to work during the winter months, although efficiency likely won’t be as high as in modern housing.
How Do Heat Pumps Compare to Boilers in Winter?
When it comes to heating your home during the cold UK winter months, choosing the right system can significantly affect your comfort, costs, and carbon footprint. Two of the most common options are heat pumps and gas boilers, each with its own advantages and trade-offs.
| Feature | Heat Pump | Gas Boiler |
|---|---|---|
| Energy Efficiency | 250–400% | 90–95% |
| Carbon Emissions | Low | High |
| Running Costs | Lower (with good insulation) | Variable |
| Upfront Cost | Higher | Lower |
| Lifespan | 15–20 years | 10–15 years |
Still unsure which system is right for you? Read our full guide on heat pumps vs gas boilers to get a better idea of the pros and cons.
What about radiator compatibility?
Most UK homes can retain their existing radiators. However, some older systems may require larger radiators or underfloor heating for optimal efficiency.
If you’re wondering whether an air source heat pump can effectively heat your radiators, our detailed blog post breaks it down clearly.
What Should You Look for in a Winter-Ready Heat Pump?
Not all heat pumps are equal when it comes to winter performance. When selecting a system for cold weather, it’s important to look for models with high efficiency ratings, strong cold-weather capability, and features that ensure consistent operation in freezing conditions. These elements will help maintain indoor comfort while optimising running costs.
Key features to consider
- Inverter Technology: Allows variable-speed operation for better temperature control.
- High SCOP Ratings: Indicates seasonal efficiency across winter months.
- MCS Certification: Ensures compliance with UK standards for renewable heating.
Recommended brands for cold climates
- Mitsubishi Ecodan
- Daikin Altherma
- Vaillant aroTHERM Plus
Want a closer look at which models perform best in cold conditions? Our guide to the best air source heat pumps highlights top-rated systems and what makes them ideal for UK winters.
Tip: Always choose MCS-accredited installers for guaranteed quality and grant eligibility.
How Can I Maximise My Heat Pump’s Winter Performance?
To get the best out of your heat pump during the UK winter, a combination of good home preparation, regular maintenance, and smart heating controls is essential. Optimising your system not only enhances performance but also helps reduce energy bills and prolong the unit’s lifespan.
Insulation is key
Ensure your home is well-insulated. This includes:
- Cavity wall and loft insulation: Heat pumps work most efficiently when your home retains heat well. Since around a third of all heat lost in an uninsulated home escapes through the walls, cavity wall insulation can significantly reduce this loss. Similarly, up to 25% of heat is lost through an uninsulated roof, making loft insulation a critical component. These upgrades ensure that the heat generated by your heat pump stays inside your home for longer, reducing the workload on the system and lowering your energy bills.
- Double or triple glazing windows: Windows can be a major source of heat loss, especially in older homes. Double or triple glazing provides a barrier that slows down heat transfer, keeping warm air in during the winter months. This not only improves comfort but also enhances the efficiency of your heat pump by maintaining a more stable indoor temperature. In colder climates, triple glazing may be especially beneficial.
- Draught-proofing: Gaps around windows, doors, floorboards, and even letterboxes can allow cold air to seep in and warm air to escape. Draught-proofing is a low-cost but highly effective way to boost your home’s thermal efficiency. By sealing these gaps, you reduce the amount of cold air infiltration, meaning your heat pump doesn’t need to work as hard to maintain a comfortable indoor environment.
Smart thermostats
Smart thermostats like Hive or Tado enable weather-compensated control, which adjusts the heat pump’s output based on the outdoor temperature. This means your system automatically delivers just the right amount of heat to maintain a consistent indoor temperature without wasting energy.
These devices can also learn your heating preferences and schedule, allowing the heat pump to operate more efficiently by pre-heating your home only when needed. Many smart thermostats offer app-based control, enabling you to monitor and adjust your heating remotely.
This is especially useful for avoiding unnecessary heating during the day or when you’re away from home. Over time, this level of intelligent control can significantly reduce your energy consumption and improve the overall comfort of your home.
Routine maintenance
Schedule an annual service to check:
- Refrigerant levels
- Coil condition
- Fan operation
- Defrost settings
Are There Financial Incentives for Installing Heat Pumps in the UK?
Yes, several schemes support winter-ready heat pump adoption.
Boiler Upgrade Scheme (BUS)
- Up to £7,500 toward installation
- Applies to air and ground source heat pumps
- Available until April 2028
You can apply via Ofgem.
Smart Export Guarantee (SEG)
If your heat pump system is paired with solar PV, you can earn money for exporting excess electricity back to the grid.
Frequently Asked Questions (FAQs)
Modern air source heat pumps used in the UK are designed to operate efficiently even in temperatures as low as -15°C, and some can continue working at -20°C. While efficiency may drop in extreme cold, heat pumps can still provide reliable heating during typical British winters. In the rare event of prolonged sub-zero temperatures, a supplementary heating source may be recommended, but for most UK homes, a well-installed heat pump is sufficient year-round.
The most efficient winter setting for a heat pump in the UK is to keep it running at a consistent, moderate temperature—typically between 18°C and 21°C. Avoid frequent changes or turning it off completely, as heat pumps work best when maintaining a steady indoor climate. Using a programmable thermostat or smart controls can help optimise comfort and efficiency.
It’s normal for a heat pump to run for most of the day during the winter months, especially in colder periods. Unlike traditional boilers, heat pumps work at lower temperatures over longer periods to maintain a steady and efficient heat. Some systems may run up to 12–16 hours a day, or even longer depending on insulation, outside temperatures, and household demand. This is entirely normal and often more energy-efficient than short, high-powered bursts of heating.
Yes, it’s usually more efficient to leave your heat pump on throughout the winter. Rather than turning it on and off, it’s best to let it maintain a steady temperature, as this avoids the energy spike that comes with reheating a cold home. Heat pumps are designed to work continuously at lower temperatures, which is what makes them so efficient.
The most efficient way to use a heat pump during winter in the UK is to:
Set a consistent indoor temperature (usually between 18°C and 21°C).
Avoid switching the system on and off frequently.
Ensure your home is well-insulated to reduce heat loss.
Use smart thermostats or timers to optimise energy use.
Clean filters and schedule regular maintenance to keep the system running smoothly.
Efficient usage helps reduce running costs while keeping your home warm and comfortable.
Our Verdict
Making the switch to a more sustainable heating system is a smart move, especially as energy costs rise and environmental regulations tighten. For UK homeowners, landlords, and commercial property owners, heat pumps offer a reliable, efficient alternative that delivers long-term savings and supports a low-carbon future.
We’ve answered the key question of how a heat pump works in winter, showing that with the right model and proper setup, they remain highly effective even during the coldest months. From EPC improvements and government grants to smart controls and scalability, there are strong reasons to consider this technology.
Myles Robinson is a seasoned expert in the boiler and home improvement industry, with over a decade of experience. He is deeply committed to environmental sustainability, actively promoting energy-efficient heating solutions to help households reduce their carbon footprint. By combining industry expertise with a dedication to environmental responsibility, Myles continues to lead efforts in transforming home heating practices towards a more sustainable future.
