AirSource heat pumps take heat from the air outside using a large surface area and transfer it inside homes like a refrigerator in reverse. They work using two pumps - a compressor and a heat exchanger that absorb warmth from the air and distribute it around the home as air or water, and can still generate heat even when temperatures are low. The UK government's Renewable Heat Incentive program pays people to produce their own heating using heat pumps or solar panels, with the goal of 15% of the country's energy coming from renewable sources by 2020, providing quarterly payments for up to 7 years including 19.10p per kWh from ground source heat pumps in April 2016.