2. Heat pumps

2.1 Principle

The heat pump principle has been known for a long time. It involves transferring heat from a low-temperature medium (cold source) to a higher-temperature medium (hot source) (figure 1 ). This transfer takes place via a refrigerant fluid, and requires the input of energy in the form of work.

In the case of a dwelling heated by a heat pump, the cold source is the outside environment, from which heat can be extracted:

• or in ambient air ;

• or in the land on which the house is built;

• either in the water of a nearby river or in the water of...