Since heat pumps transfer heat from one place to another rather than generate it through the combustion of fossil fuels, they're up to four times more efficient than a natural gas furnace, depending on the local climate, according to a Rocky Mountain Institute analysis.
Equipment and installation costs typically run from $4,000 to $12,000 for an air-source heat pump, depending on the size of the pump, the brand, and whether you use a ductless system. That compares with $2,000 to $6,000 for a gas furnace, but the U.S. Department of Energy estimates that a heat pump can lower a homeowner's energy costs by hundreds of dollars a year.
Meanwhile, a study published in October in the journal Nature Energy found that houses with heat pumps get a premium of as much as $17,000 on average when they sell. The environment also benefits: A 2018 paper published in the Electricity Journal found that air-source heat pumps could reduce household greenhouse gas emissions from heating in California by as much as 54%.