This sustainable energy source is a popular choice for new self-build homes. We look at what a ground source heat pump is, how easy installation is and what it will cost.
Image: During Tom and Danielle Raffield's timber extension to a Grade II-listed cottage, which featured on Grand Designs in 2017, the couple installed a ground source heat pump on the plot.
Renewable energy sources are the next frontier of self-building, and there's a host of options available to you to improve your home's eco-credentials. You may be familiar with solar power, but what do you know about ground source heat pumps?
These systems are great renewable sources, as they transfer 3 times more energy into the home than they use to extract it, and it's also 3 times more efficient than gas to heat your home, according to ground source heat pump providers Nu-Heat.
If you're new to the concept, here's what you need to know...
What is a ground source heat pump?
Image: Installation of the Greenstore Low Energy Circulation Pump costs between £8,000 and £12,000 from Worcester Bosch
At around a metre below ground, temperature is relatively constant between 7°C and 10°C, no matter what the weather and climate looks like on the surface. This thermal energy is something that can be harnassed by a heat pump to power your home.
A ground source heat pump collects this energy through a series of plastic pipes, laid in the ground within the top few metres of the surface. The pipes contain an anti-freeze liquid which absorbs heat – this liquid is then compressed to increase the temperature, before this heat is extracted and transferred to the pump, ready to be sent to radiators, underfloor heating and hot water storage.
How is it installed?
Installation of a ground source heat pump can be disruptive, which is why they're often an attractive option for those building homes from scratch who can build it into their plans. You will need to dig trenches into the ground, the size of which will depend on your needs and the quality of the ground available. As an example, a typical 8kW output heat pump would require 200m of trench, across several loops, meaning an overall area of 400 sqm required.
There are several ways to lay these trenches, including single trenches, coiled pipes or laid in a format similar to underfloor heating. Ground source heat pumps can also be installed in vertical boreholes if you only have a small plot of land, but this requires specialist machinery and installation which can raise the costs involved.
Usually, the trenches are located close to the home, however, in properties with large amounts of adjunct land, this can be achieved, especially where the ground conditions are better suited. The heat pump itself is usually located in the home.
How much does it cost?
Typically, costs for a ground source heat pump can range anyhere from £10,000 to £20,000, depending on the complexity of the project.
If your installer is MCS-accredited, ground source heat pumps qualify for the Renewable Heating Incentive – a financial reward for those who install renewable energy sources in their homes, which could equate to quarterly payments for 7 years, alongside efficiency savings.