What are ground source heat pumps?
Ground source heat pumps are low-carbon heat-generating systems that usually circulate a mixture of water and antifreeze round a loop of pipe buried in the ground, which maintains a temperature of around 15°C even in winter. In new buildings, this loop can be buried vertically into the ground. When the liquid is pumped around the loop, it absorbs thermal heat from the ground. Mostly, this heat is solar heat stored in the surface of the earth. At depth, it is likely to be a mixture of solar and planetary heat. This heat can be transferred to radiators and underfloor heating systems, and it can heat water. The length of the loop depends on the size of the home. Normally the loop is laid flat or coiled.
What are water source heat pumps?
Water source heat pumps operate on a similar basis to ground source heat pumps but the coils are in water, e.g. a pond or river.
What are air source heat pumps?
An air source heat pump is a low-carbon heat technology, which looks rather like an air conditioning unit positioned on or near the outer wall of a building. It uses a fan to extract ambient heat from the outside air. It works on the same principle as a domestic fridge, but in reverse.
There are two types of ASHP:
- An air-to-water system uses heat to warm water. Heat pumps heat water to a lower temperature than a standard boiler system, so they are more suitable for under floor heating.
- An air-to-air system produces warm air, which is circulated by fans.
For air to air heat pumps, we need to resolve several issues before we will be ready to include them in the RHI. This includes resolution of how to measure direct air heating, including separating out the heating and cooling output. There is also the wider question of how best to provide support for a technology that is often installed for the purpose of providing cooling to a building but which we also want to be used for heating.
For air-to-water heat pumps there are no concerns over the measuring of heat, but we do not at this stage have sufficient evidence for the costs of air-to-water heat pumps outside the domestic sector to be in a position to provide support for that technology from the start of the scheme.
We will be considering whether and how we can include all air source heat pumps in the RHI from 2012.
Performance issues
In response to the Energy Saving Trust heat pump trial, the MCS heat pump installer standard has been revised. The latest version (Version 3) is available to download from the Microgeneration Certification Scheme: Installer certification web page. At the launch of the revised standard, the Secretary of State urged installers to design to the new version of the standard as soon as possible. The old version of the standard (Version 2) will be removed from service on 6 December 2011.
Heat pumps installed under the Renewable Heat Premium Payments scheme are being monitored to evaluate improvements in installation practices and customer satisfaction.
Heat pump certification
At micro-level (<45kW), there are MCS standards for heat pumps for installer companies and products. MCS installers and products are mandatory for FITs, and installer companies must belong to a consumer code of practice. At the moment there is only one, the REAL Assurance Code .
At the moment there is no other certification scheme considered ‘equivalent’ to MCS that is an EN45011 scheme, but if there were, it would also have equal access to FITs.
Grants
Grants are available for a range of microgeneration heat technologies which meet the criteria of the Renewable Heat Premium Payments Scheme (RHPP).
Microgeneration heat technologies which meet certain criteria will be eligible for financial incentives (Renewable Heat Incentive).
Permitted planning
Getting planning permission can be a barrier to householders wishing to install microgeneration technologies. In England and Scotland, changes to permitted development rights were introduced on 6 April 2008 and 12 March 2009, but these excluded air source heat pumps for reasons of possible noise and amenity issues.
Ground source heat pumps have permitted development rights.
For more information, visit the Energy Saving Trust website and the Planning Portal.
Permitted planning and air source heat pumps
Last year the Department of Communities and Local Government (DCLG) consulted on proposals to extend permitted development rights (PDR) to various categories of renewable energy technology, including air source heat pumps and domestic wind turbines. PDR removes the requirement to submit a planning application to the local planning authority for developments meeting specified conditions, saving costs and time. But in the case of air source heat pumps, potential impacts such as noise need to be carefully addressed. The consultation setting out the details and the Government’s proposals can be found on the archived CLG website.
Air Source Heat Pump installations are now eligible for permitted planning, if they meet criteria set out in the MCS planning standards available on the MCS website.
Recent and future reports/consultations/ responses relevant to heat pumps
Sources of further information about generating your own energy
- For further background information on generating your own energy onsite, see the Energy Saving Trust's website[External link] or call the Energy Saving Trust’s “Act on Co2” advice line: Tel 0800 512 012
Suitable technologies
Suitable products
MCS installer companies are able to give consumers advice on specific products and impartial advice on the suitability of individual technologies. They are required under MCS standards to give accurate written estimates of likely energy outputs from a technology.
Further information
Carbon Trust guide: Down to Earth
This guide on the selection, installation and operation of ground source heat pumps in low-carbon buildings is based on experiences of the Low Carbon Buildings Programme.