The efficiency of any heat pump depends on its type and performance ratings. In climates where temperatures seldom drop below freezing, a heat pump is a more efficient means of heating and cooling a home than using a gas furnace and an air conditioning unit.
To judge the efficiency of a particular heat pump, look for its seasonal energy efficiency ratio to measure its performance when cooling and its heating seasonal performance factor to measure its performance when heating. Higher ratings indicate more efficiency. A good-quality heat pump should have a SEER of at least 14 and an HSPF of at least 8.