How it works
An air source heat pump is a low-carbon heat technology, which looks like an air conditioning unit on or near the outer wall of a building. It uses a fan, rather like an air conditioning unit, to extract ambient heat from the outside air. It works on the same principle as a domestic fridge, but in reverse. A water source heat pumps work in the same way, using solar heat stored in water, such as a garden pond.
There are two types of ASHP:
a) 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.
b) An air-to-air system produces warm air, which is circulated by fans.
Performance issues
ASHPs cost £5,000-£10,000 to install. Running costs for space heating are around £440 per year depending on proper design, appropriate sizing and the levels of insulation already in place. The efficiency of air source heat pump systems is measured by a coefficient of performance (CoP). This is the amount of heat they produce compared to the amount of electricity needed to run them.
The benefits of air source heat pumps
- Lower fuel bills: air source heat pumps run on electricity, so there is no need to pay for gas, oil or solid fuels for heat (or to be located on the gas grid).
- Less electricity use: heating with an air source heat pump is much more efficient than using electric radiators.
- They save space: an air source heat pump system is compact, and requires no storage for fuel.
- ASHPs become more renewable as the grid decarbonises. If the pump is run by renewable electricity, ASHPs can be entirely renewable sources of energy, if operated by renewable electricity.
- Some ASHPs may require boosting below freezing point, and some have integrated systems to do this.
Support
Due to noise from the fan, permitted planning for air source heat pumps has not been introduced but an announcement by the Department of Communities and Local Government is expected during summer 2010. The £131m Low Carbon Buildings Programme currently supports air source heat pumps and provides grant funding to charitable, community groups and public sector organisation projects. Organisations can apply for 50 percent of the cost for installing approved technologies. ASHPs were listed for tariffs in the recent Renewable Heat Incentive consultation. Decisions on RHI have not yet been taken.