In the UK the ground a few metres below our feet keeps a constant temperature of about 11OC throughout the year. This is approximately the average air temperature, derived from solar energy, which it absorbs and holds steady because of its high thermal mass. Ground-source heat pumps (GSHPs) take advantage of this steady temperature.
Although electricity drives a compressor to upgrade the steady low level heat to a higher usable temperature, and pumps which circulate fluid around a loop of pipe in the ground, heat pumps are considered to generate renewable heat because each unit of electricity can deliver several units of solar-derived heat.
GSHPs usually work by chilling an antifreeze liquid and pumping it through underground pipes where, being colder than the ground, it absorbs the warmth and heats up a few degrees. This warms a chilled refrigerant in the heat pump enough to evaporate it. The warmed vapour is then compressed, greatly increasing its temperature.
This heat is then transferred, via a heat exchanger, into your home’s heating and hot water systems causing the refrigerant to cool and condense back into a liquid. Its temperature drops again to well below zero when it passes through an expansion valve, ready to start the process again.
Three options are available for the groundloop: borehole, straight horizontal and spiral horizontal (or 'slinky'), or a combination. Each has different characteristics allowing you to choose the most suitable for your property.
Horizontal trenches can cost a lot less than boreholes but require greater land area. For slinky coil, a metre-wide trench of about 10m length can provide for about 1kW of heating load, compared to 15-20m of borehole or 20-30m of trench with two passes of straight pipe, all depending on ground conditions.
Correct sizing of the heat pump and the ground loop is crucial to the effective and efficient operation of the system and will depend on your building’s heat requirements and the ground conditions. At the outset it is important to implement all possible energy efficiency measures such as roof, wall and floor insulation and draught-proofing to minimise your heat demand.
When sizing a system it is important to consult a professional installer for expert advice. A heat pump can be designed to meet 100% of space heating requirements but may be sized to provide less, so needing some form of supplementary heating for the very coldest days of the year, either immersion heaters in the heat pump system, or some separate heat source such as a wood-burning stove. Heat pumps will usually heat domestic hot water to 50-60OC so an immersion heater must be programmed to raise this periodically for a while to kill any bacteria.
Heat pumps operate most effectively in very energy-efficient buildings, ideally new builds. Whilst they will provide heat in any situation, their efficiency is very sensitive to the flow temperature demanded of them, which is a function of the size of emitter (radiator or underfloor pipework) and the rate of heat loss.
You should consider the following issues if you are considering a ground source heat pump. An accredited installer will be able to provide more detailed advice regarding suitability.
The cost of a professional GSHP installation is dependent on property, location and the type of groundloop installation used, and ranges from about £1,250 to £2,000 per kW of peak heat output, excluding the cost of the heat distribution system (eg. underfloor heating).
Trench systems are cheaper so tend to be at the lower end of this range. The installed cost of a typical 12kW system, for example, would vary between £15,000 and £24,000 plus the cost of the distribution system. The price per kW gets lower as systems get larger.
By harnessing an inexhaustible resource, a heat pump uses much less energy than a typical heating system to provide the same benefit. In a well-designed system, up to four units of heat are delivered for each unit of electricity consumed. Because of this, it also has lower CO2 emissions. A good heat pump system (running on mains electricity) causes 70-80% fewer CO2 emissions than an equivalent oil boiler.
Ground source heat pumps are low-maintenance, low noise solutions. The underground elements can be expected to last up to 50 years while the other parts of the system have a reasonable life expectancy of 15-25 years. The actual lifetime will depend on the quality of the unit and its installation. If it is over-sized and therefore starts up much more frequently than it should, the compressor’s lifetime may be significantly shortened.
Ground-source heat pump systems are supported under the Government’s Renewable Heat Incentive (RHI) IF registered before end March 2021. This should return most or all of your capital cost in quarterly payments over 7 years. Interest-free loan may also be available via the Energy Saving Trust.
A well-designed GSHP system in an energy-efficient dwelling will cost less to run than an oil, LPG or direct electric (eg. storage heater) system, and potentially mains gas. Approximate comparative running costs per kWh as at January 2019 were as follows:
|Heat pump (at 350% efficiency)||5.0p|
|Night Storage Electricity||11.5p*|
(Source: Sutherland Tables January ‘19)
*Price for radiator use only, not peak tariff backup or hot water heating
For information on possible loan funding contact Home Energy Scotland on 0808 808 2282 or visit https://www.energysavingtrust.org.uk/scotland/home-energy-scotland
The Energy Agency is a registered charity established in 1999. We provide free and impartial advice to households, businesses and communities in south west Scotland on:
The Energy Agency is a “data controller” and this document explains how we process your information.
We manage a number of schemes. Please read the scheme below that applies to you.
For all of the schemes we gather your personal information which may include name, address, telephone numbers, email address, date of birth, age, sex, employment status, tenure, benefits, income, savings bracket, bank details, fuel expenditure, fuel type, how you pay your energy bills, third party details, number of dependent children under 18, signature.
Please read below to find out what other information we may collect for each scheme.
*some data is shared anonymously
If we process your information based on your ‘Consent’, you have the right to withdraw your consent at any time. Withdrawing your consent may mean that we cannot provide a service to you.
For the Home Energy Efficiency Programmes for Scotland Area Based Schemes (HEEPS: ABS) we process your information based on ‘Contract’. You will enter into a contract with the Energy Agency in terms of which the Energy Agency will employ and manage a contractor on your behalf. Either party can withdraw from the contract with one months’ written notice.
If you apply for an Energy Agency loan for HEEPS:ABS we process your information based on ‘Contract’. This agreement is between the Energy Agency (lender) and householder (borrower). The agreement is a standard Fixed Sum Loan Agreement regulated by the Consumer Credit Act 1974. You have the right to withdraw under the terms of the above Act.
We take information security seriously and regularly review the systems, policies and procedures we have in place to protect your information and ensure these are implemented.
We will not process your information without your consent. If your data includes “special category data” we will not process this without your explicit consent.
Where we pass information on to a third party, we ensure that this is passed securely and that they have adequate security measures in place to store your data.
We do not share your information with any third parties for marketing purposes.
We will keep your information for:
Schemes – 7 years
Monitoring - 1 year
Financial - 7 years
You have the right to request a copy of the personal information we hold about you. A request can be made verbally or in writing to Liz Marquis, Director, Energy Agency, Watson Peat Building, Auchincruive, Ayr, KA6 5HW
Proof of identity must be established before we supply a copy of your personal information. We will respond to your request within one calendar month of receiving it.
If you are asking about information relating to another person, a relative for example, we need to be sure you have the authority to act on that person’s behalf. Normally this can be done through evidence of a ‘Power of Attorney’ or similar document.
You also have the right to ask us to rectify, erase, restrict, object or withdraw your consent to processing the personal information we hold about you. You can also ask us to provide data in a suitable format to transfer to another organisation – portability. If applicable, we will comply within one calendar month.
If you would like to make a complaint contact:
Information Commissioner's Office
45 Melville Street
Edinburgh, EH3 7HL
Tel: 0303 123 1115
Cookies are text files placed on your computer to collect standard internet information and visitor behaviour information. This information is used to track visits to our website.
Our website contains link to other websites. This Privacy Notice only applies to this website so when you link to other websites you should read their own Privacy Notices.
We regularly review our Privacy Notice to ensure it is up-to-date. This Notice was last updated on 31/8/20.
Your use of the Energy Agency Web Site is subject to these terms and by using the Site you show your agreement to such terms. If you do not accept our terms, please do not use the Web Site.
Ownership of Web Site
This Web Site belongs to Energy Agency, Watson Peat Building, Auchincruive, Ayr, KA6 5HW
Headings used in these terms and conditions are for convenience only and shall not affect their interpretation.
The images, logos and names on this Web Site which identify Energy Agency or third parties and their products and services are proprietary marks of Energy Agency and/or the relevant third parties. Nothing contained in this Web Site shall be deemed to confer on any person any license or right on the part of Energy Agency or any third party with respect to any such image, logo or name.
Energy Agency reserves the right, at any time and without prior notice, to remove or cease to supply any product or service contained on this Web Site. In the event that such removal takes place we shall not be liable to you in any way whatsoever for such removal.
Phone Calls and Emails
Telephone calls using the telephone numbers provided on this Web Site and email correspondence with Energy Agency at the email addresses accessible through, or discernible from, this Web Site may be recorded or monitored. By using such communication methods you are consenting to the recording or monitoring of the same.
The price of calls may vary depending on your telecoms supplier. Please check with your operator for exact charges.
This Web Site is for non-commercial, personal use only. The services contained on this Web Site may be supplied on a commercial basis on payment to Energy Agency or its service or product suppliers of its charges from time to time. Please contact us on Tel: 01292 521896 | Email: firstname.lastname@example.org
In the event that you use any of the services contained on this Web Site for commercial use, Energy Agency shall be entitled to charge you at its applicable rates in respect of such commercial use.
The copyright in the material contained in this Web Site belongs to Energy Agency or its licensed source. Any person may copy any part of this material, subject to the following conditions:
the material may not be used for commercial purposes;
the copies must retain any copyrights or other intellectual property notices contained in the original material;
the products and technology or processes described in this Web Site may be subject to other intellectual property rights reserved by Energy Agency or by other third parties with no license granted in respect of those intellectual property rights); images on this Web Site are protected by copyright as its text by IPR and may not be reproduced or appropriated in any manner without the written permission of their respective owner(s).
Changes to Terms and Records of Agreements
We reserve the right to change these terms and conditions at any time by posting changes on the Web Site. It is your responsibility to review the Web Site terms and conditions to ensure you are aware of the latest terms and conditions. Your use of this Web Site after a change has been posted will be deemed to signify your acceptance of the modified terms and conditions. We recommend that you print off and retain for your records a copy of these terms and conditions from time to time and a copy of any terms and conditions relating to any product or service which you apply for online, together with any related application form completed and submitted.
Any amendment to terms and conditions must be agreed in writing by us, or, if appropriate, by the relevant company or individual supplier with whom you contract.
Whilst Energy Agency has taken due care and attention in the preparation of the contents of this Web Site, this Web Site and the information, names, images, pictures, logos, icons regarding or relating to Energy Agency or our products and services marketed on the site (or to third party products and services), are provided on an 'as is' basis without any representation or endorsement being made and without any warranty of any kind, whether express or implied, including but not limited to, any implied warranties of satisfactory quality, fitness for a particular purpose, non-infringement, compatibility, security and accuracy.
To the extent permitted by law, all such terms and warranties are hereby excluded. In no event will Energy Agency be liable, whether in contract or tort (including negligence or breach of statutory duty) or otherwise for any losses sustained and arising out of or in connection with use of this Web Site including, without limitation, loss of profits, loss of data or loss of goodwill (in all these cases whether direct or indirect) nor any indirect, economic, consequential or special loss.
Energy Agency does not represent that the information contained in this Web Site is accurate, comprehensive, verified or complete, and shall accept no liability for the accuracy or completeness of the information contained in this Web Site or for any reliance placed by any person on the information.
Energy Agency does not warrant that the functions or materials accessible from or contained in this Web Site will be uninterrupted or error free, that defects will be corrected or that this Web Site or the server that makes it available are virus or bug free or represent the full functionality, accuracy, reliability of the materials.
If any of these Terms and Conditions (or any terms and conditions relating to a product or service referred to in this Web Site) should be determined to be illegal, invalid or otherwise unenforceable by reason of the laws of any state or country in which such terms and conditions are intended to be effective, then to the extent of such illegality, invalidity or unenforceability, and in relation to such state or country only, such terms or condition shall be deleted and severed from the rest of the relevant terms and conditions and the remaining terms and conditions shall survive, remain in full force and effect and continue to be binding and enforceable. Nothing in these terms and conditions shall exclude Energy Agency's liability for death or personal injury resulting from negligence of Energy Agency.
Intellectual Property Rights
All Intellectual Property Rights (including, without limitation, all database rights, rights in designs, rights in know-how, patents and rights in inventions (in all cases whether registered or unregistered and including all rights to apply for registration) and all other intellectual or industrial property rights in any jurisdiction) in any information, content, materials, data or processes contained in or to this Web Site belong to Energy Agency or its licensed source. All rights of Energy Agency in such Intellectual Property Rights are hereby reserved.
Jurisdiction and Law
Energy Agency makes no representation that any product or service referred to on or through the Web Site is appropriate for use, or available in other locations. The information and other materials contained in this Web Site may not satisfy the laws of any other country and those who choose to access this Site from other locations are responsible for compliance with local laws if and to the extent local laws are applicable.
These Terms and Conditions and any terms and conditions relating to products or services described in this Web Site shall be governed by and construed in accordance with the law of Scotland. Disputes arising in relation to the same shall, unless otherwise expressly agreed, be subject to the exclusive jurisdiction of the courts of Scotland.
Links to other Web Sites
Certain (hypertext) links, advertisements or suppliers promotion will lead you to Web Sites that are not under the control of Energy Agency. When you activate any of these links, you will leave Energy Agency Web Site by opening a new window and we have no control over and will accept no responsibility or liability in respect of the material on any such other Web Site. By allowing links with third party Web Sites Energy Agency does not intend to solicit business or offer any security to any person in any country, directly or indirectly.
Every effort will be made to carry out the contract but its due performance is subject to cancellation by Energy Agency or to such variation as we may find necessary as a result of inability to secure labour, materials or supplies or as a result of any act of God, War, Strike, Lockout or other labour dispute, Fire, Flood, Drought, Legislation, or other cause (whether of the foregoing class or not) beyond the sellers control.
We have tried to make this website as accessible as possible and easy to use for everyone, regardless of circumstance or ability.
All our page templates comply with the WCAG Priority 2 checkpoints as a minimum requirement. And we make every effort to ensure that all the content on our site meets this standard too. We are making every effort to ensure that we don't exclude any users. For example:
We try to publish all our text content as accessible HTML rather than in other formats such as PDF. Where we do publish PDFs or other formats our policy is to make them as accessible as we can.