A heat pump is an HVAC system that moves heat from one place to another rather than generating it by burning fuel. In summer it acts as an air conditioner, moving heat from inside to outside. In winter it reverses, extracting heat from outdoor air (even cold air) and moving it inside.
Because heat pumps move heat instead of creating it, they are 2-4 times more energy efficient than traditional electric resistance heating. Modern cold-climate heat pumps can operate effectively down to -15°F outdoor temperatures.
The three main types are: air-source heat pumps (most common, use outdoor air), ground-source/geothermal (use stable ground temperatures), and mini-split heat pumps (ductless systems ideal for additions and retrofits). Heat pumps qualify for federal tax credits under the Inflation Reduction Act.