Ambitious government targets and rising climate awareness among homeowners have led to a real shift towards greener energy in the UK. And technology has caught up. Air source heat pumps (ASHPs) have moved from a niche offering to a viable option for people looking to reduce their energy bills and lower their carbon footprint through retrofitting.
What are air source heat pumps?
Air-source heat pumps extract heat from outdoor air and transfer it indoors, providing low-carbon heating and hot water year-round, even when outdoor temperatures are cold. A water source heat pump (WSHP), on the other hand, takes heat from a water source such as a lake or well. AHSPs are more common in the residential market.
ASHPs are a really great solution for retrofitting because they usually don’t require major groundwork or large outside spaces. UK planning law generally permits them, so homeowners are able to install them without an extensive planning process, depending on the space location and type. This makes them particularly practical for suburban or rural households, where other low-carbon solutions, such as ground source heat pumps, may not be as feasible.
While ASHPs do work best with well-insulated homes, they can be installed in nearly any property with bigger radiators. This helps manage the lower flow temperature needed for efficient running. British Gas offers installation and service for air-source heat pumps. The UK government has just expanded its Boiler Upgrade Scheme. This offers a £2,500 discount on the installation of air-to-air heat pumps.
How air source heat pumps work
The air source heat pump process is similar to how refrigerators operate but in reverse. The process is possible thanks to a refrigerant which absorbs heat from the ambient air. This air then compresses to raise its temperature, enabling efficient heating of radiators, underfloor heating systems, or hot water tanks.
The benefits of air-source heat pumps
One major advantage of air-source heat pumps is their environmental performance, particularly compared with conventional fossil-fuel heating. ASHPs enable a shift away from gas and oil, reducing carbon emissions. Air source pumps produce up to 70% less CO2 than a gas boiler and zero emissions at the point of use. They are also three times more energy-efficient than traditional boilers. This can enable savings of around £100 per year with smart tariffs.
Cost considerations of air source heat pumps
The cost of an air source heat pump installation is a real concern for retrofitters – for obvious reasons. For a typical UK household, the supply and installation of an air-source heat pump should cost between £3,000 and £15,000, according to Checkatrade. This cost also depends on whether additional work is needed, such as improved insulation or new/additional radiators.
However, any air source heat pump cost consideration needs to take in more than just the upfront financial investment. Day-to-day running costs of an efficiently installed heat pump are typically lower than oil or LPG heating and compare very favourably with direct electric heating. For those considering the move away from an oil-burning system, there are the peace of mind benefits and the lack of fuel delivery to consider. Combined with renewable electricity from solar panels or green tariffs, air-source heat pumps have potential to deliver even greater cost savings as the UK grid decarbonises.
Maintenance for air-source heat pumps can also be relatively low. Annual checks by a qualified engineer are usually sufficient to keep a system running efficiently.
For every unit of electricity used, three to four units of useful heat are provided. Over the lifetime of the pump – typically 15 to 20 years – these savings add up to a substantial decrease in the building’s carbon footprint.
Planning ahead
Successful air source heat pump installations need careful design, correct sizing and expert installation. If you’d like some help in knowing where to start, Letchworth Garden City Heritage Foundation have published a helpful guide. If you’re retrofitting, the journey should really begin with a whole-house plan. This should involve surveying the property to determine how much heat it loses, which areas require additional insulation, and whether any heat distribution systems (such as radiators and underfloor heating) will be compatible with the lower flow temperatures of an air-source heat pump.
It’s worth bearing in mind that many older properties were designed for hotter systems (such as gas or oil boilers running at 70°C), whereas an air source heat pump is most efficient around 35–45°C. You might want to consider changing your radiators - for example, switching small or single-panel radiators for larger versions. You should also consider topping up your loft or wall insulation and sealing draughts.
Are air source heat pumps noisy and difficult to install?
Air source heat pumps aren’t as noisy as you might think. Modern ASHPs are designed to run quietly and can produce less noise than a dishwasher, provided they are installed in the right place and have unobstructed airflow.
The installation itself, if planned efficiently, usually takes no more than a couple of days. The process includes upgrading controls and connecting the heat exchanger to the existing system. After installation, good installers will provide a handover that includes clear operating instructions and servicing guidance.
The common good
Installing an air source heat pump is a clear commitment to community-minded, sustainable living. And while there are a few practical considerations and an upfront investment to consider, the long-term rewards – predictable energy bills, reduced emissions, cost savings, and a commitment to a green future – can be fantastic value.
And it’s all for the greater good. Retrofitting a home with a well-installed air-source heat pump is one of the most effective steps you can take to secure a comfortable, affordable, and sustainable future for you and the home you leave behind.
If more and more households switch to low-carbon heating, this collectively lowers demand for fossil fuels and can reduce grid strain at peak times. It also helps support local installer economies. As the energy transition accelerates, the homes that move early and plan these upgrades properly will be one step ahead of the game. Is now the right time for you to switch to an ASHP? Find a certified installer on the Microgeneration Certification Scheme website.
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