How does the temperature of outdoor air affect heat pump efficiency?

The efficiency of a heat pump is significantly affected by the temperature of the outdoor air. As outdoor temperatures drop, particularly in colder climates, the heat pump’s capacity to extract heat from the outdoor air diminishes. This occurs because the differential between the indoor and outdoor temperatures is less favorable for the heat exchange process that the heat pump relies on.

The heat pump operates by transferring heat from the outside air into the home. As the outdoor temperature decreases, there is less thermal energy available in the air, which causes the system to work harder to extract sufficient warmth. This increased workload results in lower efficiency ratings, typically measured by the coefficient of performance (COP), since it requires more energy input from the heat pump to achieve the same level of heating output.

Understanding this relationship is crucial for assessing heat pump performance in various weather conditions, which is vital for selecting the appropriate system for a specific residence and climate.