An introduction to heat pumps

Heat pumps offer a highly efficient way of generating heat and will play a pivotal role in the decarbonisation of the UK’s heat supply.

Heat pumps are powered by electricity, making them easy to connect to the existing network. The rapid decarbonization of electricity from renewable energy sources like solar panels and wind turbines means that not only are heat pumps a low carbon heat source now, but will become even lower over the coming decades as the electricity grid decarbonizes even further.

By combining a heat pump with energy saving measures, renewable energy generation and battery storage technology, homes and businesses can achieve a tremendous reduction in the environmental impact of their heating, and in many cases a corresponding decrease in fuel costs.

This is especially important with regards to the decarbonisation of heating throughout rural villages in Sussex, many of which currently rely on heating oil or Liquid Petroleum Gas.

For this reason, heat pumps are expected to form a fundamental pillar of the UK’s transition strategy towards a Net Zero emissions economy, and we expect to see a widespread uptake of this technology over the coming years.

Different types of heat pump

There are three types of heat pump which can be installed – an air source heat pump, a ground source heat pump, and a water source heat pump. The most appropriate solution for a given property will depend on a number of factors, with available financial resource and physical space being probably the most important.

Air source heat pumps are the most common type of heat pump due to their lower cost and comparative ease of installation. This blog will examine the costs and benefits of installing this type of heat pump.

Ground source heat pumps are more complicated to install and usually require deep boreholes to be drilled. You can read more about this type of heat pump at the Ground Source Heat Pump Association website.

Water source heat pumps need to be installed close to a water source of sufficient size and flow to avoid freezing, this can be fresh or sea water. Heat is extracted from the water source  and converted for use in the home. Water source heat pumps can often be more efficient than an air source heat pump, but they can also be tricky to install and require more equipment to operate.

air source heat pump banner - heating sussex - brighton hove energy services co-op
A 7kW Daikin air source heat pump installed by BHESCo at the Montessori Place School in 2016

What is an air source heat pump?

Heat pumps are not a new technology. They have been in use for at least thirty years in countries like Germany and Scandinavia which are far more advanced than the UK in terms of decarbonising their heat supply.

An air source heat pump is a device which absorbs ambient heat from the air outside of your property and transfers it to a water system for use inside your property. For this reason, an air source heat pump is located externally and adjacent to a property. It looks a lot like an air conditioning unit, and its technology is similar to that used in most refrigerators.

A heat pump uses a refrigerant to absorb latent heat in the air, which is then compressed to increase its temperature. The heat is then transferred to a water system for use in radiators, underfloor heating, or hot water tanks.

A typical heat pump can provide 3 to 4 units of heat for every unit of electricity used to power the heat pump.

The heat that is extracted from the air is simply transferred from outside to inside a building, which is why an air source heat pump is considered as a form of renewable heat generation.

Heat can be extracted from the air irrespective of the weather and heat pumps can function in temperatures as low as -20oC.

How much does an air source heat pump cost?

The cost of an air source heat pump may be determined by the following factors:

  • the power output of the unit (measured in kilowatts)
  • the energy input to heat output ratio (known as the ‘Coefficient of Performance’ or ‘COP value’)

As a general guide a typical air source heat pump for a domestic property will cost in the region of £6,000 to £10,000.

To identify the optimum size of unit for your home or business you will need to consider the heating requirements of the property as well as the thermal efficiency of the building.

In addition to the cost of the heat pump unit itself you will need to consider the installation costs from a locally certified heat pump professional and possible upgrades to the existing property’s radiators or underfloor heating system.

The importance of the 'Coefficient of Performance' or 'COP value'

The reason that heat pumps are considered to be highly efficient is because they are able to deliver more heat energy as an output than the amount of energy input required to operate the pump.

This is referred to as the Coefficient of Performance, or the COP value.

If a heat pump has a COP value of 3 for example, this means that for every 1kW of electrical energy that goes into the heat pump we can expect an output of 3kW of heat.

A typical COP value for a heat pump as a seasonable average is in the range of 2.5 – 4.0, a properly designed and installed system should achieve at least 3.0.

Understand more terms relating to heat pumps with this Heat Pump Glossary

Air source heat pumps and the Renewable Heat Incentive

Because the heat that is generated from heat pumps is derived from a naturally renewable source, it can be classified as a renewable energy source and is eligible for the UK Government’s ‘Renewable Heat Incentive’ (RHI).

This subsidy scheme is similar to the now defunct ‘Feed-In-Tariff’ scheme that existed to encourage the uptake of solar power generation. The Renewable Heat Incentive rewards homes and businesses with financial payments in relation to the levels of heat that they produce from renewable sources.

For a typical domestic household of 2-3 bedrooms, homeowners can expect to receive around £1,260 each year. RHI payments are made each quarter and eligible for seven years from the date that the technology becomes operational.

You can find out all the information you need on the Renewable Heat Incentive from Ofgem.

CASE STUDY: The Unity Centre, Lewes

The Unity Centre is a yoga and meditation facility which took over the Old Turkish Baths building in Lewes in 2019. At that time, the property was nothing more than an empty shell of a structure – there was no running water, no heating, and no lighting.

BHESCo were engaged to design the most cost-effective and environmentally sustainable heating solution that was in line with the ethical values of the Unity Centre.

Following a detailed site-survey and a rigourous examination of anticipated heating requirements, BHESCo proposed that the ideal solution was a 22kW air-source heat pump that would deliver heat via an underfloor heating system.

Community Energy UK 3
22kW MasterTherm air source heat pump installed by BHESCo at the Unity Centre in 2019

The technologies were installed in the summer of 2019 before the Unity Centre opened their doors in September of that year.

Sevanti Atwood, the owner and founder of Unity Centre, said:

There were a few times when I considered stopping. Without BHESCo, none of this would have been possible”.

"There were a few times when I considered stopping. Without BHESCo, none of this would have been possible".
sevanti attwood portrait unity centre lewes
Sevanti Attwood
Founder & Director

By using this innovative and low-carbon technology for their heating requirements we expect the Unity Centre to achieve considerable financial and environmental benefits.

As with most of our project installations, the upfront cost of this project was met through BHESCo’s ‘Pay As You Save’ finance initiative.

Expected Annual Savings


17 tonnes CO2

How is heat delivered to the property?

An air source heat pump is an excellent way of generating heat from a low-carbon and low-cost source, but it will not deliver that heat to your property in and of itself. The heat must be transferred into the rooms of your property via a conduit such as underfloor heating or raidators.

Underfloor heating is generally considered to be the best accompaniment for heat pumps as heat can be emitted as a lower temperature over a large surface area.

However, underfloor heating may be limited by practical considerations or budget constraints, and so wall mounted radiators may offer the best solution in certain circumstances.

air source heat pump - The Unity Centre underfloor heating
Underfloor heating being installed by BHESCo at the Unity Centre. Underfloor heating is an ideal way to deliver the heat generated from an air source heat pump.

Heat pumps can be used to meet all of your hot water needs

In addition to delivering efficient heat throughout the property via underfloor heating or radiators, an air source heat pump is also able to meet all hot water requirements needed for taps or showers 

Due to their low temperature operation, heat pumps need specially designed hot water cylinders in order to gain maximum performance efficiency.

Compared to the use of fossil fuels such as oil and gas, heat pumps can provide an efficient and environmentally friendly way to meet your property’s hot water needs.

Why air source heat pumps are a great solution for homeowners and developers

The urgent need to reduce CO2 emissions, ever tightening building regulations, and rising energy costs mean that implementing more efficient heating sources has never been more pressing.

It is vital that homeowners housebuilders, and developers ensure their homes are as energy efficient as possible and air source heat pumps provide one possible solution to making this a reality.

Heat pumps provide an effective, low-carbon energy solution for a wide range of situations. They are suitable for both modern properties and older homes that have good levels of thermal insulation.

An air source heat pumps can reduce fuel costs by up to 30% compared to an existing oil system, and can reduce CO2 emissions by up to 60% compared to gas in a new build property.

An air source heat pump will save money on fuel bills because it is a much more efficient way of heating a space, meaning the property will consume a lot less energy.

Where possible, savings can be increased even further by powering a heat pump through a combination of solar power and battery storage technology.

daikin air source heat pump - montessori place - brighton hove energy services co-op
A 7kW Daikin air source heat pump installed by BHESCo at the Montessori Place School

Why heat pumps offer an ideal solution for rural village communities in Sussex

Air source heat pumps can deliver significant reductions to heating bills and environmental impact, and present a particularly attractive solution to off-grid homes in rural Sussex villages.

Many of these communities are not connected to the gas grid, instead relying on oil for heating, which can be subject to volatile price fluctuations in addition to having a highly detrimental impact on local air quality and the atmosphere in general.

Eradicating oil as a heating source is also a high priority for the UK Government. The 2017 Clean Growth Strategy set out a long term vision to reduce pollution and climate harming emissions. A key policy proposal was to:

Build and extend heat networks across the country, underpinned with public funding (allocated in the Spending Review 2015) out to 2021

Phase out the installation of high carbon fossil fuel heating in new and existing homes currently off the gas grid during the 2020s

[The Clean Growth Strategy 2017; Leading The Way To A Low Carbon Future, p.13]

Air source heat pumps offer a solution for rural communities to switch to a cleaner and potentially cheaper heating source with minimal disruption and without needing to connect to the national gas grid.

Furthermore, by switching to air source heating, residents will no longer need to worry about the hassle of organising fuel deliveries and how these costs may very from year to year.

To further drive down costs and make heating provision even more environmentally sustainable, property owners and developers should look to combine air source heating with solar panels.

If you live in the Sussex area and are interested in installing an air source heat pump for your home or business then contact BHESCo to find out how we can work together to improve the energy performance of your property.

We may even be able to help cover the upfront cost of installing your heat pump technology through our innovative ‘Pay As You Save‘ finance initiative.


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