Aerothermal energy – how heat pumps use energy from the air
Aerothermal energy is becoming increasingly popular across the United Kingdom as a low-carbon, highly efficient alternative for heating, cooling, and domestic hot water. Using air-source heat pumps (ASHPs), this technology extracts thermal energy from the outside air—even in low temperatures—and converts it into usable heat for the home.
In line with the UK’s goal to achieve net zero carbon emissions by 2050, the government has been actively encouraging the transition to low-emission heating systems. Schemes such as the Boiler Upgrade Scheme (BUS) and updates to Building Regulations Part L are accelerating the adoption of aerothermal systems in both new builds and retrofit projects.
Thanks to their versatility, efficiency, and reduced reliance on fossil fuels, aerothermal systems are proving to be a smart long-term investment for UK homeowners concerned about rising energy bills and climate impact.
What Is Aerothermal Energy and How Does It Work?
Aerothermal energy refers to the process of extracting renewable heat from the outside air and transferring it indoors through an electrically powered heat pump. This system operates via a thermodynamic cycle, using a refrigerant that compresses and expands to absorb and release heat.
In colder months, the system captures ambient heat from the air—even at temperatures as low as -15°C—and delivers it indoors for space heating. In warmer months, the process can be reversed, allowing the system to function as a cooler. Many ASHPs can also supply domestic hot water year-round.
These systems are remarkably efficient. For every unit of electricity consumed, an air-source heat pump can deliver between 3 and 4 units of thermal energy. This makes it far more effective than traditional electric or fossil fuel-based systems.
Aerothermal setups are compatible with underfloor heating, low-temperature radiators, and fan coil units. They can also be paired with photovoltaic solar panels to reduce dependence on the grid and maximise energy efficiency.
As part of the UK’s broader decarbonisation strategy, aerothermal energy offers a practical solution that aligns with both environmental goals and long-term energy savings.
Benefits of Using Heat Pumps in the Home
Air-source heat pumps offer a host of advantages that make them an increasingly attractive option for UK households. From improved energy efficiency to lower running costs, the benefits extend beyond heating.
One of the most significant advantages is energy efficiency. Unlike traditional boilers, which typically operate at 90% efficiency, a modern ASHP can achieve efficiency rates of 300–400%, delivering multiple units of heat for every unit of electricity consumed.
These systems provide all-in-one functionality, capable of heating, cooling, and providing hot water from a single unit. This consolidation reduces installation complexity and overall equipment footprint.
They are also environmentally friendly, producing no on-site emissions and reducing reliance on natural gas. When powered by green electricity, such as through a renewable tariff or solar panels, they can operate with an extremely low carbon footprint.
Another benefit is low maintenance. With fewer moving parts than combustion-based systems and no need for flues, filters, or gas inspections, annual servicing is typically quick and affordable.
From a comfort perspective, ASHPs maintain a consistent indoor temperature and operate quietly—ideal for both rural homes and city flats. Additionally, modern systems allow for smart controls and zoning, enabling customised heating in different areas of the home.
Over time, the energy savings, ease of use, and environmental benefits make ASHPs one of the most forward-thinking choices for UK homes.
Main Components of an Aerothermal System
An aerothermal heating system consists of several integrated components that work together to extract, convert, and distribute heat efficiently. Understanding each part helps homeowners appreciate how the system operates and what to expect from installation.
The outdoor unit houses a fan, an evaporator coil, and a compressor. This unit draws in outside air and transfers its thermal energy into the system using a refrigerant. Even during winter, it can extract heat from cold air.
Inside the home, the indoor unit—often called a hydrobox or hot water module—transfers the heat from the refrigerant into the central heating circuit or hot water tank. It may also include a small auxiliary heater for support during peak demand.
Depending on the system setup, homes may feature heat emitters such as underfloor heating, low-temperature radiators, or fan coils. These are specifically designed to work with the lower flow temperatures typical of heat pump systems (usually 35–55°C).
A hot water cylinder is often included for domestic hot water, with many models designed specifically for heat pump integration. Some systems may also include a buffer tank to reduce compressor cycling and improve efficiency.
Control is managed via programmable thermostats or smart home systems, allowing for remote management and temperature zoning to optimise energy use.
When professionally installed and correctly sized, these components work seamlessly to deliver comfort and energy efficiency throughout the year.
Aerothermal vs Geothermal and Other Heating Systems
Aerothermal and geothermal heat pumps both provide low-carbon heating solutions, but they differ in source, cost, and complexity. Understanding these distinctions helps determine which system is best for your property.
Aerothermal systems, or air-source heat pumps, extract heat from ambient air. They are easier and more affordable to install because they require only an outdoor unit and minimal structural modifications. As such, they’re suitable for most UK homes, including flats and terraced houses.
Geothermal systems, also known as ground-source heat pumps, extract heat from the earth through buried loops. While they offer excellent performance and stability, installation is more invasive and costly, requiring significant space and excavation—making them less practical for urban or compact properties.
Compared to traditional gas boilers, aerothermal systems have no on-site emissions and significantly lower energy use. They’re also exempt from the future gas boiler phase-out being considered under UK energy policy.
Electric heaters are easy to install but highly inefficient, leading to high running costs. Oil boilers, still common in off-grid areas, are less efficient and contribute to higher carbon emissions.
Overall, aerothermal systems strike the right balance of affordability, flexibility, and environmental responsibility—especially suited to the UK’s mild to moderate climate.
Maintenance and Lifespan of Aerothermal Systems
One of the key advantages of aerothermal systems is their low maintenance requirement. Designed for reliability and durability, these systems generally require less attention than conventional boilers or combustion-based systems.
The outdoor unit should be kept clean and unobstructed. Leaves, debris, and snow should be removed regularly to ensure optimal airflow and performance. The coils and fan should also be inspected annually.
The indoor components, including the hydrobox and hot water cylinder, require occasional checks to confirm correct pressure, valve function, and system fluid levels. Professional servicing once a year is sufficient to maintain optimal performance and ensure warranties remain valid.
Unlike gas boilers, ASHPs do not involve combustion, so there’s no need for gas safety inspections, flue cleaning, or carbon monoxide monitoring. This makes them safer and simpler for homeowners to manage.
Modern units are equipped with self-diagnostic software that alerts users to maintenance issues, helping prevent major faults and reducing the risk of breakdowns.
With proper maintenance, an air-source heat pump typically lasts 15 to 20 years, which is comparable to or better than many gas boiler systems. Their efficiency and reliability contribute to consistent comfort and peace of mind.
Energy Consumption and Long-Term Savings
Aerothermal heat pumps are among the most efficient home heating systems available in the UK, offering substantial savings on energy bills—particularly as electricity continues to shift toward renewable generation.
The key performance metric is the Coefficient of Performance (COP), which indicates how many units of heat are produced per unit of electricity consumed. A COP of 4, for example, means the system delivers four times the energy it uses.
In a well-insulated three-bedroom home, an aerothermal system can reduce heating costs by 30–50% compared to a conventional gas boiler, and even more when replacing older electric or oil-based systems.
Pairing an ASHP with solar PV panels enhances savings further, as the electricity required for the system can be offset by solar generation—particularly useful during spring and autumn when heating demand coincides with sunlight availability.
Initial installation costs range from £7,000 to £13,000, but government grants such as the Boiler Upgrade Scheme (BUS) can reduce this by £7,500 for eligible households in England and Wales.
With proper usage and regular servicing, homeowners can expect a payback period of 6 to 10 years, after which the system continues to provide low-cost, efficient heating and hot water.
Is Aerothermal Energy Viable in the UK?
Aerothermal energy is not only viable in the UK—it is actively promoted as part of the country’s transition to low-carbon housing. With supportive policy, funding incentives, and favourable climate conditions, the UK is well-positioned for widespread adoption of air-source heat pumps.
The Department for Energy Security and Net Zero has set ambitious targets for low-emission heating, aiming to install 600,000 heat pumps annually by 2028. The Boiler Upgrade Scheme offers direct financial support for homeowners to switch to ASHPs.
In terms of climate, the UK’s relatively mild winters are ideal for air-source systems. Even in colder areas such as Scotland or the North East, modern ASHPs can maintain performance at sub-zero temperatures.
The Energy Saving Trust and Ofgem both endorse heat pumps as a practical, scalable solution for reducing household carbon emissions and lowering energy costs.
Furthermore, the UK’s electricity grid is increasingly supplied by wind and solar power, meaning heat pumps will become even greener as the grid continues to decarbonise.
For homeowners planning ahead, investing in aerothermal energy is a future-proof choice that meets today’s needs and tomorrow’s energy standards.
Is Investing in a Heat Pump Worth It?
Investing in an aerothermal heat pump may involve a higher upfront cost than a conventional boiler, but the long-term savings, environmental benefits, and added home value make it well worth considering.
With grants of up to £7,500 available, many homeowners are able to access this technology at a reduced initial cost. Once installed, the reduction in energy use and elimination of gas bills make monthly expenses more predictable and often significantly lower.
Beyond financial gains, ASHPs provide quiet, even heating, are safer than combustion systems, and require less maintenance. Many are also compatible with smart home systems, allowing for optimised energy use and convenience.
As UK housing policy continues to move away from fossil fuels, properties equipped with heat pumps are likely to become more attractive in the housing market, potentially increasing resale value.
In short, if you’re planning a long-term home upgrade or building a new, sustainable dwelling, an air-source heat pump is a sound and forward-thinking investment.
Frequently Asked Questions (FAQ)
1. Can I replace my gas boiler with a heat pump?
Yes, especially if your home is well insulated. Many UK homes are already converting to heat pumps as a cleaner, more efficient alternative.
2. Will it work during the British winter?
Absolutely. Modern air-source heat pumps are designed to operate efficiently in temperatures as low as -15°C.
3. Are there grants available to help with the cost?
Yes. The Boiler Upgrade Scheme offers up to £7,500 towards installation costs for eligible households in England and Wales.
4. How long does it take to install?
Most installations take between 2 to 5 days, depending on the system and whether hot water and emitters are being upgraded.
5. Does it require underfloor heating?
Not necessarily. While underfloor heating is ideal, many heat pumps can work efficiently with radiators designed for low-temperature systems.