A guide to ground source heat pumps
In this series of ‘understanding retrofit’ blogs, we’ll be explaining different retrofit measures which can improve the energy efficiency of homes – how they work, what types of homes they will be right for, what installation looks like, and more.
Want us to cover a particular measure? Drop us an email to info@cosyhomeoxfordshire.org and we’ll see what we can do.
What is a Ground Source Heat Pump?
Ground source heat pumps (GSHPs) extract heat from the ground using pipes buried in the garden and use this to heat your home and hot water. It’s a low cost and low carbon method of heating.
How do Ground Source Heat Pumps work?
A Ground Source Heat Pump circulates a mixture of water and anti-freeze around a loop of pipe, called a ground loop, which is buried in your garden. This is usually a horizontal trench about a metre below ground, but in some instances it could be a vertical trench (this is very rare in the UK).
The fluid then passes through a compressor that raises it to a higher temperature, which can then heat water for the heating and hot water circuits of the house. The cooled ground-loop fluid passes back into the ground where it absorbs further energy from the ground in a continuous process as long as heating is required.
The ground stays a fairly constant temperature throughout the year, and so it isn’t an issue to keep the heat pump going during the winter months.
What types of home does a Ground Source Heat Pump work for?
The key factor for Ground Source Heat Pumps is that they are laid in the ground, so they are only suitable for homes with substantial outside space in which to host them.
Whether or not a Ground Source Heat Pump is right for you is also largely down to your motivations and preferences. Whilst you will always make significant carbon savings, they are expensive to install and you may not save money on your energy bills – especially true if your heating is currently gas-powered, as electricity is still needed to power the pump (which is more expensive than gas).
What are the expected costs and savings?
The Energy Savings Trust estimates that it costs £14,000 to £19,000 to install a Ground Source Heat Pump. Running costs will vary depending on the size of your home and how much energy is needed to heat it.
The savings you make on your annual energy bills will depend on what kind of heating system you are swapping away from, but the the Energy Savings Trust predicts savings as below (April 2019 data).
| Moving from: average gas heating system | Moving from: average oil heating system | Moving from: average electric heating system | |
| Energy bill savings (£/year) | £25 to £30 | £20 to £30 | £1000 to £1090 |
| Carbon emissions diverted (kgCO2/year) | 2.5 to 2.7kg | 3.9 to 4.2kg | 3.6 to 3.9kg |
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