In the United States, every heat pump sold has an energy efficiency label that includes its seasonal energy efficiency ratio. Manufacturers calculate the SEER for the unit by dividing the total British thermal units of heat it removes during the heating season by the watt-hours of energy it consumes.
Because heat pumps also provide heat, the energy efficiency label also includes the heating season performance factor. Manufacturers calculate the HSPF in a similar manner to the SEER rating, using the total heating Btu requirement and energy consumption.
As of 2015, heat pumps with a minimum SEER rating of 12 and a minimum HSPF of 7 qualify for the Energy Star label. The most efficient heat pumps have a SEER rating of 13 to 18. In colder climates, where the unit provides more heat than cooling, the HSPF is a better indicator of efficiency than the SEER rating.
Leaky ducts and poor airflow affect the efficiency of a heat pump whether it is providing heating or cooling. Installation technicians should check the ductwork for leaks and make repairs as necessary. It is sometimes possible to correct poor airflow by cleaning heat exchanger coils or adjusting blower speeds; however, this correction often requires replacing part or all of the duct system.