The Digital Learning Paths provides a brief description of heat pumps and how they work. Heat pumps are devices that transfer heat from a low-temperature source to a higher-temperature sink using mechanical energy. They can provide both heating and cooling by utilizing the principles of thermodynamics. The primary components of a heat pump system are the compressor, evaporator, condenser, and expansion valve. The system operates in a cycle, with the refrigerant changing states between gas and liquid as it absorbs and releases heat. In winter, the heat pump extracts heat energy from the outdoor air and transfers it into the home. The refrigerant evaporates, absorbing heat from the outdoor air, and then it is compressed and used to warm up the indoor air. The heat is extracted from the indoor air, causing the refrigerant to condense back into a liquid, and the cycle continues. In summer, the heat pump works like a standard air conditioner. The refrigerant absorbs heat from the indoor air, evaporates, and then it is compressed and releases heat to the outdoor air, condensing back into a liquid. The efficiency of a heat pump is measured by its coefficient of performance (COP), which represents the ratio of heat output to energy input. Heat pumps are known for their energy efficiency as they transfer heat instead of generating it. It's important to note that heat pumps are most effective in moderate climates where there is a significant temperature difference between the heat source and the heat sink. In colder climates, supplemental heating may be required when the outdoor temperature is very low.