Explain how a heat pump works and its advantages over conventional heating.

A heat pump moves heat from a low-temperature source to a high-temperature sink using the vapor compression cycle in reverse. For heating, it extracts heat from outside air, ground, or water and delivers it indoors. The COP of heat pumps ranges from 2-5, meaning for every unit of electrical energy input, 2-5 units of heat are delivered. This makes heat pumps 200-500% efficient compared to resistance heating at 100%, significantly reducing energy costs and carbon emissions.