Heat Pumps
Heat pumps work like a refrigerator, moving heat from one place to another. To move heat takes energy. Energy can come in the form of electricity (vapour compression) or be thermal energy (absorption heat pumps). Heat pumps can provide space heating, cooling, water heating and sometimes exhaust air heat recovery. [1]
Heat pumps use a little energy (usually in the form of electricity) to move available energy as heat from A to B. For every unit of energy purchased as electricity, several units of heat are delivered. So, relating the energy purchased to the energy delivered, heat pumps can be 300% or 400% efficient [2]
Ground Source Heat Pumps
Geothermal energy involves tapping into the heat generated by the Earth's absorption of the heat radiated by the sun. Ground Source Heat Pumps (GSHP) extract this energy, and transfer it into a building for space and water heating, They can also remove heat from a building and deposit it into the ground to cool the building during hot weather.
According to The Carbon Trust's Renewable Energy Sources Technology Overview, "The heat is collected through a series of underground pipes laid about 1.5m below the surface, or from a borehole system. In both of these options, water is re-circulated in a closed loop underground and delivered to the heat pump, which is usually located inside the building. Heat pumps cover a wide range of capacities, from a few kw to many hundreds of kw machines that heat or cool large, multi-storey buildings."
The Energy Saving Trust's detailed guidance recommends careful consideration of the costs and benefits, noting that capital costs may be higher, although running costs may be lower, than for many other types of heating.
Site suitability will be determined by local geological conditions, but, as with many technologies, they are cheaper to install in a new build than to retrofit. The system requires accurate calculations, and the length of loop required needs to be determined exactly - adding a ‘safety margin' is not recommended.
Air Source Heat Pumps
Air heated by the sun is processed through an electrically driven or gas-powered pump system, turning it into high-grade heat. Air source pumps are ideal for construction where extensive ground work or well drilling is not possible.
The air is usually collected through an air-source collector located outside of a building. The system can also be reversed to remove heat from internal areas in summer. Planning permission may be required for the siting of the external unit.
System performance is dependant on the external air temperature. The whole-life of the system is likely to be 10-15 years, and they are most cost-effective to retrofit when an existing boiler is in need of replacement.
The Energy Savings Trust's guide to installation is downloadable from www.energysavingtrust.org.uk/uploads/documents/.pdf
Ground Source Heat Pump Association
http://www.nef.org.uk/gshp/gshp.htm
UK Heat Pump Network
http://www.heatpumpnet.org.uk/
UK Heat Pump Association
http://www.feta.co.uk/hpa/
Groundswell: The underground newsletter of the UK Ground Coupled Heating & Cooling Community
http://www.earthenergy.co.uk/
Energy Saving Trust's introduction to ground source heat pumps for the UK with fact sheet which can be downloaded.
http://www.est.org.uk/myhome/generating/types/groundsource
Best Practice Programme publications on ground source heating: access the link and enter "ground source" in keyword search.
http://www.est.org.uk/bestpractice/publications/index.jsp
http://www.energysavingtrust.org.uk/generate_your_own_energy/types_of_renewables
http://www.lowcarbonbuildings.org.uk/info/installers/find/installerfind
MCS 007 Heat Pumps scheme document
MCS 004 Solar collectors scheme document
MCS 011 Testing and acceptance criteria
MIS 3005 Microgeneration Heat Pumps Installer Standard
MCS 002 Information on Building Regulations and European Directives
International Ground Source Heat Pump Association
http://www.igshpa.okstate.edu/
International Energy Agency Heat Pump Centre
http://www.heatpumpcentre.org
The Energy Saving Trust's detailed guidance recommends careful consideration of the costs and benefits, noting that capital costs may be higher, although running costs may be lower, than for many other types of heating.
http://www.energysavingtrust.org.uk/uploads/documents/housingbuildings/CE82%20-%pdf
BERR Low Carbon Buildings Programme (LCBP)
Find out about the LCBP grant programme for ground source heat pumps. This site includes links to installers, products, manufacturers and grant application forms.
http://www.lowcarbonbuildings.org.uk/micro/ground/
Energy Saving Trust (EST)
Ground source heat pumps
http://www.energysavingtrust.org.uk/content/download/1547/10364/version/2/file/Ground
EST (March 2004) Domestic Ground Source Heat Pumps: Design and Installation of closed loop systems (CE82)
Aimed at both specifiers and users, this guide details the types of systems, how to achieve an integrated system, how to maximise efficiency, capital and running costs as well as Dos and Don'ts.
http://www.energysavingtrust.org.uk/uploads/documents/housingbuildings/.pdf
National House Building Council
The NHBC have produced two reports which review the opportunity for microgeneration and renewable technologies. The documents include guides to, technology overview, cost effectiveness and local impact.
http://www.nhbcfoundation.org/Portals/0/NF7%20-%20A%20Review http://www.nhbc.co.uk/NHBCpublications/LiteratureLibrary/
Report on heat pumps in the UK
www.energysavingtrust.org.uk/uploads/documents/housingbuildings/GIR72%20-%20Heat
[1] Environmental Change Institute, 2005 (February 2005)
[2] http://www.heatpumpnet.org.uk
