Heat Pumps In Colder Climates

With Scotland and other parts of the UK aiming for net-zero carbon emissions by 2050 and planning to phase out gas and oil boilers in new builds by 2024, many homeowners are wondering about alternative heating solutions. One of the concerns is whether or not a heat pump, which is the eco-friendly alternative to a boiler, can operate in colder climates.

The good news is that heat pumps work well in Scotland and colder climates. This article will give you invaluable insights into various heat pump installations.

We’ll answer all your questions relating to whether heat pumps can function in colder weather, which temperatures are best for each relevant heat pump system and what could possibly keep these pumps from operating at optimal efficiency.


Do Heat Pumps Work Well In Colder Weather?

Yes. Heat pumps work by transferring heat from one place to another. This means they move heat from the outside and transfer it indoors which produces heat for a home. Even in cold weather, there’s still heat in the outside air.

There are two main types of heat pumps, namely:

  1. Air source heat pumps (ASHPs)
  2. Ground source heat pumps (GSHPs)

Water source heat pumps, another type of heat pump, extract water from rivers and lakes. The water passes through the compressor to generate heat. These are less common.

In this article, we will be discussing air source and ground source pumps. Essentially, both work in the same way, by providing heating and hot water to Scottish homes. The difference between the two lies in their functionality.

  • An air source heat pump extracts heat from the outside air. The efficiency of these systems can be reduced in very cold weather. However, modern air source heat pumps are designed for optimal efficiency.
  • Air source heat pumps have two varieties. An air-to-water system distributes warmth through your wet central heating system. This is ideal for larger radiators and underfloor heating systems. An air-to-air system produces warm air from rotating fans to circulate through your home.
  • Ground source heat pumps work slightly differently. These heat pumps draw warmth from the ground, which has a more reliable or stable temperature. A ground source heat pump offers consistent warmth, heating and hot water, throughout the year, regardless of the weather.

Side note: Generally, a heat pump struggles to provide sufficient hot water, due to the high temperatures needed. If you require excess hot water systems, a solar thermal system may be a better option.

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Do Air Source Heat Pumps Work Well In Colder Climates?

Now that we’ve established their efficiency, let’s delve deeper into how air-source heat pumps function in colder climates.

A modern air source heat pump can operate at optimum efficiency in temperatures as low as -25 °C to -15 °C.

As mentioned, air source heat pumps extract heat from the outdoor air and transfer it indoors. The extracted air is converted into a fluid state which passes through the heat pumps’ compressor. The temperature of the liquid is increased, thus generating heat for your heating system and hot water cylinder. In simpler terms, air source heat pumps work much like a fridge, but in reverse.

When compared to gas and oil boilers, air-source heat pumps provide heat at lower temperatures over longer periods. They are more energy efficient and help reduce your energy bills.

Note: Scotland has many home improvement schemes available for eligible households. These funding grants or loans can be used to upgrade heating systems (such as new boilers and heat pumps) and install wall insulation solar panels – to name a few. It is part of the country’s ambitious plan to reach net-zero carbon emissions by 2050 and is available to offset installation costs for qualifying homes.

heat pump snow scotland

Does Colder Weather Make Heat Pumps Less Efficient?

  • In lower temperatures, air source heat pumps use more power to extract and transfer heat. These types of heat pumps generally ‘lose efficiency’ in cold temperatures; however, they still operate well in temperatures as low as -25 °C to -15 °C.
  • Air source heat pumps are 300% – 400% more efficient on average. This means they generate 3 to 4 units of heat per unit of electricity. This number drops to about 200% – 2 units of heat per unit of electricity – in lower temperatures.
  • Ground source heat pumps extract heat from the ground. This is a stable heat source, providing consistent heat no matter the temperature.

Does a poorly insulated house impact heat pump efficiency?

Yes. If your home is poorly insulated, consider upgrading your insulation before considering installing a heat pump. Loft, roof and wall insulation reduces the amount of heat lost from your home, preventing heat pumps from overworking.

What Is The Best Heat Pump For Colder Climates Like Scotland?

While temperatures can get chilly in Scotland, especially in the Highlands, temperatures are not as extreme as in other northern countries, like Norway or Estonia.

A ground source heat pump is probably your best bet for colder climates, as it provides consistent heat for your heating systems, regardless of the weather or temperature.

If these types of heat pump is not accessible to you though, an air source heat pump will work just as well. Air source heat pumps are the most common heat pumps, after all.

Before you decide which heat pump to go for, you need to consider the cost of installing a heat pump system.

  • An air source heat pump is cheaper to install, with a typical system costing about £13,000 – £20,000. Home improvement grants from the Scottish government, such as the ECO4 scheme, are available for eligible households to offset part of the installation costs.
  • A ground source heat pump is more costly, costing between £22,000 and £40,000 – the latter if a borehole is needed. A well-maintained ground source heat pump can last for about 20 years.
  • Both ASHPs and GSHPs require electricity to run. However, the running costs of these systems are far cheaper than fossil fuel central heating systems, like gas and oil boilers.

What Is The Best Temperature For Heat Pumps?

An air-source heat pump works best in hotter regions where there is an abundance of warm air. When temperatures are above 18 °C, air source heat pumps provide the most heat for households.

Since ground source pumps extract heat from below the surface, these temperatures are more consistent, generally in the range of 10 °C – 12 °C.

Are Heat Pumps Popular In Colder Countries?

Yes. Heat pump installations and systems are popular in colder countries, such as Scotland, Norway and Sweden. Statistics show that 1 in 4 Norwegian households – where temperatures can drop to -6.8 °C – own a heat pump system.

Fun fact: Poland and Lithuania are fast adopting heat pump installations, where temperatures often drop to below freezing.

heat pump poland

Will A Heat Pump Cover Help Protect Against Cold Weather?

This is a debatable topic with the majority leading towards pump covers as a necessity. This is because pump covers can protect your heat pump system from harsh weather conditions, such as rain, hail, and snow. Covers can prolong your pump system’s longevity and prevent it from freezing in low temperatures. A well-maintained heat pump system can last for 20 years.

How To Tell If The Winter Weather Is Causing Problems With Your Heat Pump?

There are a few things to watch out for in winter, such as:

  • The heat pump has built up ice: While most heat pumps have automatic defrost mechanisms, there may come a time when it isn’t functioning correctly. Built-up ice could just mean there is excess ice or sleet on the external (outdoor) unit but it could also mean there is a problem with the internal mechanics, such as valves, controls, or fans.
  • The heat pump is not producing heat or blowing cool air: During colder months, the heat pump system may take a little longer to transfer heat from the outer coils to the internal heating system. This is due to the pump having to ‘warm up’ – or defrost – first. Alternatively, it could indicate malfunctioning internal components, such as compressors or refrigerants.
  • Your energy bills are rising: It’s normal for energy costs to rise in winter, especially if you have an air source heat pump. These pumps need more power in low temperatures to extract heat from the outside. However, if you notice unusually high energy bills, it could mean your heat pump is in overdrive, or you have an ill-sized pump for your house size.

Either way, if your heat pump is not functioning at its optimal efficiency, it’s best to contact a professional. They will conduct a full analysis of your heating system and pump, ensuring peace of mind.


Yes. Heating systems, such as heat pumps, are more energy-efficient than traditional gas boilers. The Scottish government has ambitious plans to ban gas and oil boilers in new builds from 2024, making heat pump installations the go-to alternative.

As mentioned, heat pumps require electricity to run. However, the running costs of these heating systems are far less than other types of boilers.

You can save between £750 and £1,400 per year with a heat pump when compared to an electric immersion heater. And up to £1,500 per year when compared to a traditional LPG gas boiler.

Yes. Typically, an air source heat pump generates 3 to 4 units of heat per unit of electricity, making them 300% – 400% more energy efficient. Heat pumps emit less carbon emissions, which means they are more environmentally friendly for the planet.

Yes. An air source heat pump is cheaper to install when compared to ground-source types. An air source heat pump installation costs roughly between £13,000 and £20,000. On the other hand, a ground source pump costs between £22,000 and £40,000.

An air source heat pump extracts heat from the air. They work similarly to domestic refrigerators but instead of generating cool air (to keep produce fresh) they convert the cold air from outside into warm air that is transferred to your home’s heating system. The generated heat can be used to heat radiators and underfloor heating systems as well as provide hot water.

Final Thoughts

While ground source heat pumps are a more reliable and stable heat source, extracting heat from the ground, they are expensive to install. An air source heat pump is the most commonly installed pump for Scottish homes and is far cheaper to install when compared to their ground-based counterparts.

Essentially, both of these pumps are energy-efficient options. They provide warmth and hot water while being more economical to run when compared to fossil fuel boilers that use coal or gas.

If you’re looking to reduce your carbon footprint, you can’t go wrong with either of these options. The Scottish government has various funding support schemes available for Scottish homeowners, who are looking to upgrade their central heating system. Schemes, such as ECO4, are easily accessible to qualifying households.

For more information, allow the team at Envirohomes Renewables to assist you with all your ECO4 government-funded ground or air source heat pump home improvement and eligibility  needs.