What is the minimum efficiency requirement for an air source heat pump in heating mode?

The minimum efficiency requirement for an air source heat pump in heating mode is evaluated using the Heating Seasonal Performance Factor (HSPF). The HSPF measures the efficiency of an air source heat pump over an entire heating season.

The correct answer, which is 7.8 HSPF, aligns with the current minimum efficiency standards established by regulatory bodies like the Department of Energy (DOE) for residential heating. This standard reflects advancements in technology and aims to ensure that heat pumps operate efficiently while minimizing energy consumption and environmental impact.

An HSPF rating of 7.8 indicates that the heat pump can provide 7.8 BTUs of heat for every watt of electricity consumed over the season, representing a higher level of efficiency compared to the lower values. Higher efficiency ratings equate to reduced energy costs for homeowners and better overall performance in heating applications, making 7.8 HSPF the minimum requirement in this context.