What is a disadvantage of air-source heat pumps?

Air-source heat pumps are known for their efficiency and ability to provide both heating and cooling. However, one significant disadvantage they face is reduced efficiency in colder climates. This happens because as the outside temperature drops, the heat pump has to work harder to extract heat from the air. Cold air contains less heat energy, which can result in a decrease in the heat pump's performance and an increase in the energy required to maintain the desired indoor temperature.

In many colder regions, the efficiency of air-source heat pumps can decline to a point where auxiliary heating systems become necessary, leading to increased energy consumption and potentially higher costs in heating during extreme winter conditions. This characteristic necessitates careful consideration when selecting heating solutions for areas that experience prolonged and severe cold weather.