General FAQs
We are unable to offer specific property advice, quote for work or recommend a specific member company as we do have to remain impartial with regards to all our members, however we have tried to answer the most frequently asked questions below.
A ground source heat pump, also known as a shallow geothermal heat pump, works by absorbing heat from the ground and transferring the heat into buildings as hot water.
The heat pump works on the same principles as a domestic fridge. In your fridge a heat pump extracts heat from the inside and transfers it to a small radiator at the back, where the heat is dissipated into the room.
In exactly the same way a ground source heat pump takes heat from the ground and transfers the heat into the building by circulating hot water though radiators, or underfloor heating pipes.
A heat pump works by increasing the temperature of a fluid it contains at the temperature of the ground using a cycle of compression and evaporation of a thermal transfer fluid fluid. When a large volume of gas is compressed into a small space the heat energy in the gas becomes concentrated, causing the gas to heat up. When the gas is then depressurised, and turns back into a liquid, energy is released. A heat pump uses a heat exchanger to capture the released energy and transfers the heat as hot water into the heating circuit of the building and hot water supply system.
Once the highly pressurised gas has condensed, and released its heat, it then becomes very cold. The heat pump uses a heat exchanger to transfer that cold fluid back into the ground where it absorbs heat from the surrounding ground and the cycle can begin again.
Yes. The same components can be designed to provide cooling in the summer.
If cooling is provided in summer, by allowing heat to escape to the ground, then this will improve the performance of heating in the following winter.
You would need to specify this requirement with your installer at the design stage.
Yes. We believe that a ground source heat pump system, is the most efficient heating and hot water system available for commercial and domestic projects; no matter how large or small.
A ground source heat pump uses electricity to operate its compressor and to pump fluid through its circuits. This accounts for around 20 – 25% of the energy requirement for the overall heating system. The remainder of the energy demand comes from the ground and this energy is free. As the heat pump actually generates energy it is a carbon positive technology; you get more energy out than you put in
A well-designed ground source heat pump installation typically provides four or even five kilowatts of heat for the consumption of one kilowatt of electricity.
A ground source heat pump installation consists of:
- a ground source heat pump in your building
- a ground array for heat exchange with the ground (pipes in horizontal trenches or vertical boreholes)
- a heat distribution system within your building (underfloor heating, radiators or air ducting)
- a control mechanism to transfer heat from where it is available to where it is needed.
The initial purchase cost of a ground source heat pump system is more than a conventional oil or gas fired boiler. The initial capital expense is offset by lower running costs, lower maintenance and low servicing requirement. There is also the security of knowledge that the majority of your heating and cooling energy comes from the ground and will not increase in price.
Be careful to avoid judging an installation on price alone. It is very important to ensure you have a well designed system if your aim is to save money over the life of the installation.
Yes, we have our own YouTube channel with lots of information and webinars that you may find useful. Click here to find out more.
Yes – there are heat pumps capable of both heating and cooling. Heat pumps are actually chillers in reverse. You will need to make sure to select a heat pump capable of this in the first place – ask your installer. And you need to make sure your emitters are capable of emitting cool as well as heat. Condensation on pipework can be a problem and normal radiators are not a good type of cooling emitter. Convector radiators are good.
Yes. A communal ground array serving a heat pump in each building has many advantages over a traditional Combined Heat and Power district network including lower installation costs, lower running costs, much lower carbon emissions and improved air quality.
A ground source heat pump uses a ground loop or borehole to exchange heat with the ground: the advantage is that a relatively constant temperature is available throughout the winter if the ground loop is large enough. There are alternatives which can also be attractive for larger buildings including open loop systems which heat exchange with open water or aquifer systems: water source heat pumps or marine source heat pumps. It is also possible to heat exchange with ambient air, but an air source heat pump is significantly less efficient when the external air temperature is cold – and this corresponds with the time when space heating is most needed.
A ground source heat pump systems offer very high efficiency, low running costs and benefit from long life. Oil-fired boilers cost considerably more to run. Even modern condensing gas boilers are more expensive to run at current gas prices, with gas prices also set to rise. All fossil fuel boilers need annual servicing to maintain efficiency and check safety.
Ground source systems are automated. Because they come with low maintenance, low running costs, low noise and are out of sight, they are often referred to as “invisible heating systems”.
One key advantage of ground source systems is that they are favoured by planning officers: with nothing to hear, nothing to see, and nothing to smell there is nothing to object to.
A well engineered commercial ground source heat pump can be expected to last 25 years – ten years longer than a combustion boiler – and the ground heat exchanger, the more expensive part of a GSHP installation, should have a life of over 100 years.
As with any valuable plant a ground source system should be covered by an annual maintenance agreement with the supplier. However, routine maintenance requirements are very low.
No, a ground source heat pump installation is invisible, makes less noise than a gas boiler and issues no gases of any kind on-site: there is nothing for anyone to object to.
No, a ground source heat pump makes less noise than a gas boiler, and very much less than an air source heat pump which drives a fan to extract heat from ambient air.
There are no hazardous gas emissions, no flammable oil, LPG or gas pipes, no flue or chimney and no unsightly fuel tanks. GSHP systems have absolutely NO site emissions. There is, therefore, no need for safety checks.
Yes. Ground source heat pump systems are ideally matched to modern warm temperature underfloor heating because a heat pump transfers heat at a higher coefficient of performance if it delivers to a large warm water circuit (like underfloor heating) rather than a small high temperature circuit (like wall mounted radiators). However, ground source systems can equally feed heat (or cooling) to air handling systems or to fan coil units.
Yes. In the UK, there is now a strong move towards alternative technologies that are sustainable and environmentally friendly. 40% of CO2 emissions are derived from the heating and cooling of buildings. Using heat pumps to transfer heat into buildings reduces carbon emissions radically, when compared to burning fuels. The arguments are even stronger where a building needs cooling in summer as well as heating in winter. Ground source heating and cooling provides sustainable energy by recycling heat between seasons.
The rapid decarbonisation of the grid means that well designed heat pump installations release much lower carbon emissions from the power stations than combustion boilers do on site.
Yes. Ground source heat pumps are normally designed to run at lower temperatures than gas boilers as this is a more efficient way of delivering heat in a new well-insulated building. When a ground source heat pump is installed to replace a combustion boiler it may be appropriate to install a high temperature heat pump to avoid the need to refurbish the heat distribution mechanism in the building.
Yes, but remember that investment in good insulation will be well rewarded, whatever the source of heat. The cost of a system is directly related to the heat losses, which will generally be higher in older buildings. Money spent on upgrading insulation levels can save on the capital cost of a ground source heat pump installation.
See case studies of heat pumps fitted successfully to older buildings.
Yes. Ground source heat pumps have been installed successfully in less well insulated houses and in Listed Buildings. If the building is not well insulated then a higher capacity heat pump can be specified or a heat pump with a higher temperature output can be installed. However, it is always wise to consider improving the insulation of building when a new heating system is installed as this may reduce the cost of the heating installation – whatever kind of heating system is to be installed. You should take advice from an installer with experience.
Find an installer near you by searching our Members Directory.
Yes. All new buildings are designed to meet Building Regulations and will be able to benefit from a ground source heat pump. Building Regulations have been designed to conserve fuel, reduce heat losses and ensure greater energy efficiency, in order to ensure that all modern properties need less heating. For a well-insulated building the size of heat pump will be smaller, it will need smaller ground loops and will therefore be less expensive. You should take advice from a GSHP installer with commercial experience.
Yes. Reverse-cycle heat pumps deliver both heating and cooling very effectively. Cooling provided by heat exchange with cold ground is inherently more efficient than air conditioning which typically exchanges heat with hot air: Renewable Cooling.
The heating cost in winter will also be reduced if you are using cooling in summer as the heat pump will have access to warmer temperatures from the ground: Renewable Heating.
A heat pump for a small building is about the size of a large fridge. More powerful heat pumps for commercial buildings do not increase in size or price as much as they do in power output.
Yes, GSHP systems are common in the USA, Canada, Sweden, Switzerland and Germany. The principles of ground source heat pumps were first described by Lord Kelvin in the 1850s and continuous development since they were first used commercially more than 50 years ago has greatly improved their efficiency. GSHPs provide a proven, reliable, cost-effective, safe and environmentally friendly alternative to combustion for heating.
Modern ground source heat pump systems are very efficient. For each kilowatt of electricity used to run the heat pump, three to four kilowatts of heat can be delivered to the building. The efficiency of a GSHP installation is very dependent on the quality of the design and installation. The efficiency of the installation is improved by utilising solar recharge of the ground.
The Coefficient of Performance (“CoP”) of a heat pump system depends on the design and quality of the installation: from as low as 2 for an air source heat pump system in unfavourable conditions, up to 4 for an unassisted ground source heat pump, and up to 8 for a well designed ground source heat pump system benefitting from solar recharge of the ground.
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