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Ground Source Heat Pump
A ground source heat pump uses heat from the ground to run our central heating. It can also cover a household’s hot water needs.
What is a ground source heat pump?
A ground source heat pump (GSHP) is a type of low carbon central heating system. Instead of burning fossil fuels, it collects heat from the ground. Using electricity, it boosts this heat so we can use it for home heating and hot water.
How does a ground source heat pump work?
Put simply, a ground source heat pump takes warmth from under the ground outside, boots it, then lets us use this warmth inside our home.
A system of buried pipes collect heat from the ground outside your home.
Since the temperature in the ground stays at a similar level throughout the year, there’s always a reliable source of heat for the system to use.
The GSHP runs on electricity. For every unit of electricity it uses, around four units are transferred to our heating. This means the efficiency of a ground source heat pump is an impressive 400%.
Ground source heat pump: a step by step explanation
- Buried pipework (called an “array”) collects heat from the ground
- Compressor and condenser heat up water in pipes
- Heated water flows to radiators, underfloor heating, and hot water cylinder
- Water from hot water cylinder can be used for bath, shower and taps
A system of pipes (known as an ‘array’) is buried in your garden. These pipes contain a mixture of water and antifreeze. This ‘brine’ mixture absorbs the heat energy from the ground.
The warmed water moves through the pipes into an evaporator. Inside the evaporator is a refrigerant with a very low boiling point. The heat from the water in the pipes boils the refrigerant, changing it into a gas.
The gas goes through a compressor. This increases the pressure, which in turn increases the temperature of the gas.
The gas moves into a condenser. The condenser contains pipes which feed the central heating. In the condenser, the gas heats the water flowing through the pipes.
Ground source heat pump pros and cons
- Low carbon form of heating
- Could help you save significantly on your energy bills
- Ground remains a reliable temperature throughout the year
- Significant upfront cost
- Disruptive installation
- You’ll need significant outdoor space
Is a ground source heat pump right for my home?
As with other types of heat pump, ground source heat pumps work most efficiently if:
- Your home is well-insulated
- You have (or are planning to upgrade to) radiators with a large surface area
For more information on these points, check out our general heat pump guidance.
There are also a few other things to think about when considering a ground source heat pump:
Do I have space for a ground source heat pump?
On average, the array needs an outdoor area roughly three times the size of your home. The installer will need to be able to get their digging equipment onto the site to put the array in. The land should be clear of trees.
If you don’t have enough space to dig trenches, it may be possible to install the array vertically. This means drilling a bore hole straight down into the ground and inserting the pipes into this hole.
The diameter of a bore hole is about 25cm. The depth can be anywhere from 75 to 200m. Depending on the size of the system, multiple bore holes may be needed.
To make sure the ground is suitable, a survey would need to be carried out.
Whether you choose a horizontal or vertical array, you’ll also need space indoors for the GSHP itself. The ground source heat pump unit is a similar size to a large fridge-freezer. If your ground source heat pump will also be supplying your hot water, then you’ll need somewhere to fit a hot water cylinder. Most ground source heat pumps have their own dedicated ‘plant room’ in a house.
Do I need planning permission for a ground source heat pump?
You won’t usually need planning permission to install a ground source heat pump. However, if you live in a listed building, or your home is part of a conservation area or World Heritage site, planning permission will likely be needed.
It’s worth checking with your local council’s planning department, just to be on the safe side.
Will a ground source heat pump save me money?
As a general rule, whether a ground source heat pump will save you money depends on:
- The type of fuel you’re switching from (e.g. gas, oil, electricity, wood)
- The energy tariff you are on (i.e. how much you’re paying per unit for electricity)
The type of fuel you’re switching from
Most of the heat energy produced comes from the ground (which is free), but there are associated running costs to consider.
Ground source heat pumps use electricity. At its best, the efficiency of a ground source heat pump is 400%. So for every kilowatt of electricity you put in, you get around 4 times that amount of energy out. This is much better than a traditional boiler, which runs at about 90% efficiency.
Ground temperature tends to stay almost the same throughout the year. This means that the efficiency of the ground source heat pump should also be fairly constant.
Even though ground source heat pumps are consistently much more efficient than fossil fuel boilers, this doesn’t automatically make them cheaper to run. This is because, at the time of writing (August 2024), electricity is more expensive (per unit) than gas.
The Energy Saving Trust (EST) have compared the running cost of a ground source heat pump to other types of heating system. The full results are available here.
To summarise EST’s findings:
- Any type of boiler with an energy efficiency rating of G
- Any kind of electric storage heaters
- Coal
- A gas boiler with an energy efficiency rating of A
- An LPG boiler with an energy efficiency rating of A
The tariff you’re on
The cost of running a GSHP will depend on your electricity tariff. You can shop around again to find a tariff which is cost-effective for a GSHP.
Some suppliers offer a tariff designed especially for heat pump users, so it’s worth looking out for these.
Ground source heat pumps cost and funding
Ground source heat pump cost
A ground source heat pump costs around £24,000. This is for the type of heat pump where the array which is buried in horizontal trenches. If the GSHP has a vertical array which is installed using a bore hole, then the average price is £49,000.
The price will vary depending on:
- How big your home is and how much heat it needs
- The make and the size (measured in kilowatts) of the GSHP unit
- Any costs from upgrading your radiators or installing underfloor heating
- How well insulated your home is
Ground source heat pump grants
Grants for ground source heat pumps are available through Home Energy Scotland.
If you are a homeowner looking to install a new GSHP, the grant funding amount is £7,500. There is also the option of a further £7,500 on top of this in the form of an interest free loan.
If you’re a homeowner in a remote or rural part of Scotland, you may be able to get a £9,000 grant for a ground source heat pump. You can also access a further £7,500 through an interest free loan.
For the most up-to-date information about heat pump grants, visit the Home Energy Scotland grant and loan page. Alternatively, you can call Home Energy Scotland free on 0808 808 2282.
Changeworks delivers Home Energy Scotland in the south east and Highlands and Islands on behalf of the Scottish Government and Energy Saving Trust.
As well as providing free, impartial expert advice to thousands of people every month to help them to keep warm in their homes for less, they identify funding opportunities for households seeking to install energy efficiency measures.
For more information, give Home Energy Scotland a call on 0808 808 2282 or email and the team will be happy to help you.