power-of-sunFor millions of years, the sun has provided all energy required to support life on Earth.  Most of this energy is not being harnessed and is just passing us by. fossil-fuelsIf we can utilise just a fraction of this energy to heat our homes, we can move away from using fossil fuels and help put a stop to the destruction of our planet.  One way in which we can do this is to use heat pumps to provide heating and hot water for our homes.

After experimenting with a freezer, Robert C. Webber built the first direct exchange ground source heat pump in the late 1940s.  The technology became popular in Sweden in the 1970s, and its acceptance has been growing slowly worldwide ever since.  By 2004, there were over a million units installed worldwide, providing 12 GW of thermal energy.

The earth is continually absorbing heat from the sun. Although the surface of the earth is subject to seasonal temperature fluctuations,  below a depth of 1.0 to 1.5 metres the ground temperature is constant at between 8 and 14°C all year round.  A ground source heat pump is designed to use this constantly renewed energy to supply your domestic heating and hot water requirements, and could reduce heating bills by up to 50%.

There are two types of ground source heat pump installation – closed-loop and open-loop.


Closed-loop systems pump an anti-freeze solutionclosed-loop-soleco through pipes buried in the ground.  The loops can be installed either horizontally in trenches or vertically in a series of boreholes.

The overall length of these loops depends on the size of the heat pump and the thermal conductivity of the ground in which they are lain. Heat losses between the antifreeze solution and the loop-pipe, the loop-pipe and the grout surround and the grout surround and the ground itself reduces the efficiency of these systems in comparison with an open-loop system.

Closed-loop systems, if poorly designed and installed, can result in freezing of the ground thereby reducing the efficiency and life of the heating system.  A closed-loop system can, however, be installed anywhere in the country irrespective of the ground conditions.


Open-loop systems are the most efficient ground source heat pump option.  They extract heat from ground water, usually abstracted from an aquifer via a borehole, which is passed through a heat pump where heat is extracted from the water.  The water is cooled byOpen Loop Article Diagram approximately 5˚C before being returned to the ground, where it immediately begins to regain heat from the earth.

This type of system will only work in areas where there is sufficient ground water available. To request a feasibility study, please click here.

H.D. Services Ltd. specialise in the installation of open-loop systems throughout South-East England, specifically in areas underlain by the chalk aquifer.

Subject to analyses, water extracted from the borehole can be filtered for domestic consumption before being returned to the ground via a harvesting tank.  Water from the harvesting tank can be used for garden irrigation and other ‘grey-water’ uses.  This harvesting tank is replenished whenever the heat pump is in operation.

An abstraction licence is not required from the Environment Agency provided the abstraction rate does not exceed 20,000 litres per day. To date, no H.D. Services Ltd. Open-loop installation has required an abstraction licence.

If you require further information regarding abstraction licences, please contact us or visit the Environment Agency website.