Air energy

The air can provide energy though a system called an air source heat pump. This basically works like reversed air conditioning equipment (where coolant is expanded - to cool it down and compressed - to heat it up). In fact they can be used as coolers in the summer time.

The system is driven by electricity, so you would still need to produce / buy this from renewable sources.

The system has a measure, called the Co-efficient of Performance, that shows how much extra you are getting from it. So for every unit of energy put into the system (in the form of electricity) you will generally get between 3 and 4 units back (in the form of heat).

The system does not need to have the expensive series of pipes like the ground-source heat pump, so it much easier to install. Like the ground source these types of system are very compatible with underfloor heating because they run at lower temperatures.