Air Source Heat Pumps

Let’s clear the air.

Air source heat pumps are the cheapest and cleanest way to heat a home in Guernsey. 

Plus, as of 2023 planning permission is no longer required for installation. See the Planning Permission section below for more information.

Do you install air source heat pumps? Let us know your details for the directory



In a well-insulated property, Air Source Heat Pumps can be around 300% efficient. 

What does 300% efficiency look like? 

For every 1kW of electricity used to power the system, a heat pump will produce 3kW of heat for your property.

See for yourself using the Guernsey cost calculator 

The heat pump’s low running costs are thanks to clever mechanics that extract heat from outdoor air and convert it into heat for your home.

How will it save on running costs? 

You only need to pay for the electricity that runs the system using a Heat Pump tariff. 

As they’re powered using electricity and use significantly less power than an electric boiler, they’re also the most environmentally friendly way to heat a home thanks, again, to their superior efficiency.

The Energy Saving Trust provides an in-depth guide to air source heat pumps if you wish to find out more from a trusted source.

Hear from Ben Fogle

How an air source heat pump works

Sometimes understood as a ‘fridge in reverse’, an Air Source Heat Pump uses free heat from outdoor air as low as -20°C to generate energy to heat your property. The ambient air temperature in Guernsey is ideal for an air source heat pump as we rarely see extremely low temperatures. 

  • The Air Source Heat Pump uses a fan to draw air into it and over a heat exchanger, which contains a refrigerant liquid
  • An evaporator uses the latent heat from the air to heat the refrigerant liquid sufficiently until it boils and turns into a gas
  • This gas is then compressed which causes it to significantly increase in temperature
  • An additional heat exchanger removes the heat from the refrigerant (turning it back into liquid) and uses it to heat the water for your heating system

Watch how it works

Are air source heat pumps for everyone?

No, air source heat pumps won’t be suitable for all properties in Guernsey and it’s best to seek specific advice from an installer. 

They’re also usually more expensive to purchase and install that other more traditional heating systems.

Generally older, draughty properties and those made of granite are less suitable. This is because a heat pump’s effectiveness lies in the property’s ability to retain heat – i.e. how well insulated it is. A home heating survey will tell you how much heat your home is losing and if a heat pump would be a suitable alternative to your current heating system.

Although planning permission is no longer required for an air source heat pump in Guernsey, there are several caveats mentioned in this document which may affect you – search for “heat pump” to see them.

Find out more about insulation in Guernsey

See how much it costs to run

A must for new builds

Developing a sustainable, well-insulated property with low running costs is one of the great joys of a major new project. And with thermal performance requirements increasing in line with the UK regulations, new properties provide the ideal living space to gain cost and carbon benefits from heating with an air source heat pump. 

Heating systems only ever need to replace the heat that is lost through the fabric of a building, such as the roof, walls and windows. This is why during a home survey your installer will do a ‘heat loss calculation’ to understand how much power a new heating system will need.

Air Source Heat Pumps can be 300% efficient (or more!) when they are able to gently heat the fabric of a building and continually provide warmth at the same rate it is lost.

During a new build, it is much easier and cheaper to install the necessary equipment and pipework, and heat pumps can integrate well with underfloor heating.

Find an air source heat pump installer

Perfect for pools

Air source heat pumps are a more affordable way to heat a swimming pool as heat from outdoor air can be captured and used to heat the water.

If you wanted to use your pool in the middle of winter, you could still rely on a heat pump to keep it warm as it operates in temperatures as low as -20°C. Using automation, set your favourite pool temperature then simply let the heat pump do the work.

Heat pump sizes will depend on how large your pool is and other elements such as the thermal properties of your pool structure, wind speed, water velocity and water table. Once installed, you’ll enjoy low running costs and zero carbon emissions around your property as you spend time in your pool.

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Planning permission

In early 2023, the new Planning Law Exemptions Ordinance came into force which states that installing an Air Source Heat Pump in Guernsey does not require planning permission – but will have certain caveats. 

Search “Heat Pump” in this document to find out more

More information

Office heating

Air source heat pumps are being used more and more in commercial and other non-domestic properties such as offices, shops, and schools. 

There are several good reasons why. 

  • Significantly reduced heating bills 
  • Office cooling to provide a controlled climate
  • Significant contribution to business sustainability and positive ESG reporting

A well-designed, correctly installed system should require minimal maintenance and last around 20 years or more.

Find your air source heat pump installer

See the Heat Pump Installer directory

How much does an Air Source Heat Pump cost to install?

An Air Source Heat Pump is a lifetime investment for your property. It could help increase your property value and will significantly reduce your bills. 

You should always ask for two or three quotes before making a final decision. However, the average cost may around £9,000 – £12,000. As an Air Source Heat Pump can last around 20 years, the low running cost means it’s possible to pay back the initial investment relatively quickly. 

It’s worth noting that Air Source Heat Pumps are a better solution for well-insulated properties and new builds. Heat pumps generally aren’t designed to take a property from a cold to warm state as quickly as possible. You may need larger radiators if you are installing a heat pump retrospectively. 

Older, draughty properties need higher operating temperatures to maintain an enjoyable internal climate. Although heat pumps can work at higher temperatures, this will reduce their 300% efficiency which will impact your cost and environmental savings.

How much does an Air Source Heat Pump cost to run?

Compared to all other heating sources, Air Source Heat Pumps are by far the cheapest to run. 

Use your current oil, gas or electric heating bill to see how much you could save with an air source heat pump using this cost calculator 

How is an Air Source Heat Pump more environmentally friendly?

Air Source Heat Pumps produce the lowest carbon emissions of any heating type.

Studies have been commissioned to understand the carbon impact of heating systems used locally and details can be found on Guernsey Electricity’s website.

Air source heat pumps operate at an efficiency rate of up to 300%, therefore, for every kWh of electricity consumed they deliver around 3kWh of heat to your home or commercial premises.

Due to this efficiency an Air Source Heat Pump installed in your property will reduce the greenhouse gas emission from your heating system by at least 90% when compared to an oil or gas heating system.



How is it possible to have 300% efficiency?

Air Source Heat Pumps generate their own heat using outdoor air, and use low-carbon electricity to drive the system. 

Depending on the level of insulation in your property, Air Source Heat Pumps can provide you with £3 worth of heat for every £1 you’ll spend on the electricity required to run your heat pump. 

The full definition is a ‘Coefficient of Performance (COP) of 3’. Energy cannot be created, it can only be converted into another form – such as heat energy – meaning it’s impossible to have more energy produced (heat) than is put in (electricity).

If 1kW of electrical energy is used to drive the compressor and pumps, the remainder is transferred from outdoor air – a heat source that would otherwise not be used. The refrigerant inside the heat pump boils at a very low temperature, which explains why Air Source Heat Pumps work in temperatures as low as -20 degrees C.

The free heat from the outdoor air is not considered an energy input, but is used to produce 3kW worth of valuable heat energy for your home within the mechanics of a heat pump.

Thinking about switching to electric heating?

It pays to plan ahead. Electrical installations are an investment and can take time to complete. Contact your preferred installer as early as possible to find out what you need to do.

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