When you’re staring out of your window at a freezing winter scene, it’s hard to believe that you could be heating your home by extracting free heat energy from the ground. It’s not science fiction – with a ground-source heat pump (GSHP), you can enjoy low-cost renewable energy all year round, not only saving you money but helping the environment at the same time.


If you’ve never heard of ground-source heat pumps – or any other kind of heat pump for that matter – read on and discover how this ultra-reliable technology can make a big difference to your heating bills.


Heat pumps work by extracting heat energy from warm locations and transferring it to areas that need heating. Ground-source units extract heat from the earth beneath your house – even in winter! What you may not realise is that once you reach a depth of two meters or more, the temperature of the ground in the UK rarely falls below 10 degrees Centigrade– it’s only the top few feet that freeze solid.


The business end of a ground-source heating system is a heat-collecting ground loop. This is a large length of small-diameter pipe and, depending on the space you have available at your property, is laid either in a trench or in a deep vertical borehole. The loop contains water plus a dose of anti-freeze, and an electric pump drives the mixture around the system.


The heat collected by the ground loop is extracted by passing the water mixture through a heat exchanger, after which the fluid flows underground again to collect more heat. The extracted energy is transferred to the heating system in your property, typically to underfloor heating or a warm-air system.


The beauty of a well-designed ground-source heating system is that the amount of electrical energy needed to drive the pump is only around one-quarter of the heat energy you can recover from the ground loop. It’s truly renewable energy with a very low carbon footprint.


So what are the drawbacks? Well, GSHPs aren’t cheap. A well-specified system costs upwards of £10,000 – although there are government incentives in the form of grants for domestic homeowners who are replacing existing non-gas heating systems. You can recover up to £1,250 of your outlay under the UK Renewable Heat Incentive scheme.


You will also be eligible to receive payments for each kilowatt-hour of heat energy that you recover using a GSHP. As of early 2013, the scheme applies to commercial users, while from July 2013 domestic users will also qualify for a rebate of up to 4.7 pence per kilowatt-hour. Overall, UK consumer organisation Which? estimates that you can save nearly £500 a year compared with the cost of the equivalent electric heating system.


When you throw in the fact that GSHPs run with minimal maintenance – only requiring a check by a professional installer every three to five years – and have a life expectancy of 10 to 20 years, it’s easy to see why they are catching on in Britain. Why not go green and enjoy the year-round benefits of renewable energy from a ground-source heat pump?