What is a ground source heat pump?

A ground source heat pump (GSHP) is an energy efficient, renewable energy solution that is particularly suited to properties on larger plots. Up to 400% efficient, this type of heat pump extracts the free heat from the ground, using this for heating and hot water. A GSHP helps to reduce your carbon footprint and can even lower your energy bills.

• Incredibly efficient, a ground source heat pump transfers around four times more energy into the property as heat than it uses to extract it from the ground
• MCS approved for the Renewable Heat Incentive (RHI)
• Well-suited to properties on larger plots
• Ground loop or bore hole installation options
• Virtually silent operation

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How do ground source heat pumps work?

Ground source heat pumps were designed to take on the role of a boiler. Where typical central heating systems burn fuel in order to generate heat, ground source heat pumps take heat from the ground.

A ground source heat pump consists of a network of pipes buried in the ground carrying a cold liquid, which gently extracts heat from the ground. The heat pump is situated indoors and extracts this free energy from the liquid, and upgrades its temperature to that suitable for heating and hot water.

Ground loops or borehole: which should you choose?

There are two ways to harvest the heat energy from the ground with a ground source heat pump: through ground loops or via a borehole. But which should you choose?

Ground loops

Ground loops are the most popular choice when installing a ground source heat pump.

Collector pipes are buried at a 1 meter depth within the ground, drawing the warmth from the ground, through to the heat pump. Any energy that is extracted is continually replenished by the sun.

To install ground loops, you need plenty of available land – at least three times the total floor area of the property, ground and upper floors combined.

Pros of GSHP ground loops

• Cheaper to install than boreholes
• If landscaping works will be happening anyway, it’s no extra upheaval
• No specialist contractors required
• The ground loop trench can be dug at the same time as laying the foundations for a new build by the groundworker.

Cons of GSHP ground loops

• A significant area of land is required, which can rule a GSHP out
• Landscaping is required
• You can’t develop the area once the ground loops are installed.

If you haven’t got the space to install ground loops but are set on a GSHP, you might consider a borehole.

Boreholes

A borehole is a vertical hole that is typically drilled between 40-120 metres deep. The ground collector, that extracts the heat energy, is dropped into this hole before being filled with a grout for added thermal conductivity.

To install a borehole, you will need a specialist contractor and the number of boreholes required depends on the project.

Pros of GSHP boreholes

• Less space required compared to ground loops.

Cons of GSHP boreholes

• Cost. Boreholes can cost as much as double in comparison to ground loops. This is due to the contractors, equipment, drilling and logistics involved
• No additional payback. The Renewable Heat Incentive tariff rate remains the same, whether you have installed a borehole or ground loops. This means the overall cost to install a GSHP with a borehole is higher
• Specialist contractor is required.

If considering a borehole, it’s worth weighing up the cost of installation versus choosing an air source heat pump which would be significantly cheaper, is well suited to properties on smaller plots and still returns an efficiency of around 300%.

Ground source heat pump plant rooms

The ground source heat pump unit is installed inside, meaning that space is required for a plant room to house the system. This is definitely something to factor in early on as it takes more space than an airing cupboard housing a boiler, which many people are used to.

As a rough guide, a typical GSHP plant room would be around 2.1 x 1m and would contain the heat pump, cylinder, pipework and the controller.

Is a ground source heat pump right for your home?

Now that you know more about ground source heat pumps and how they are installed, there are a few other things to think about before deciding on a GSHP.

1. Isulation. For a ground source heat pump to work efficiently, keeping running costs low, it’s essential that the property is well insulated, ideally up to current building regulations.

2. Heat emitter. A GSHP is at its most efficient when producing low water temperatures, so it should be paired with a low temperature heat emitter, like underfloor heating, to maximise its efficiency.

3. Motive. If you are looking to create a sustainable home, moving away from fossil fuels with modest running costs, then a GSHP sounds like a good match. If your main motive is to save money, but you live in an older property with access to mains gas, the initial outlay and potential savings compared to sticking with gas will be minimal, so a GSHP might not be right for you.

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Ground source heat pump costs

When considering a ground source heat pump, cost is always going to be a key consideration. You’ll want to find out more about how much a GSHP costs to install, their running costs and what to expect with maintenance.

A well-designed GSHP will be as much as 4x more efficient than a gas boiler, deliver low running costs and benefit from Renewable Heat Incentive payments – all whilst being kinder to the environment at the same time!

How much does a ground source heat pump cost?

Ground source heat pump installation costs vary according to the project and whether ground loops or boreholes are used to extract the heat from the ground.

As a rough idea, you can expect the GSHP and its components to cost around £10,000, and a ground loop installation to cost around £4000.

A GSHP does cost more than an ASHP or a fossil fuel boiler, but this is reflected in the much higher RHI tariff, meaning most homeowners are likely to recoup this initial outlay over 7 years.

What are the running costs of a ground source heat pump?

A well-designed ground source heat pump system in the right type of project will deliver low running costs over its lifetime.

The table below shows how the running costs of ground source heat pumps compare to common fossil fuel alternatives. Remember, you could also receive RHI payments to further reduce the running costs of a GSHP.