A heat pump is an all-in-one heating and cooling unit. There are a few different kinds, but the most common ones extract warmth from the air. Then, they move it inside (to heat the home) or outside (for cooling). That requires a lot less energy than traditional heating systems — like boilers, furnaces and electric radiators — that work by warming up the air inside your house.

“There’s a fair amount of heat even in the cold air,” said Vijay Modi, a professor of mechanical engineering at Columbia University. He estimated that a home heat pump could cut electricity use by as much as two-thirds compared with more traditional heating systems.

The Northeast Energy Efficiency Partnerships , a nonprofit group focused on energy efficiency, found that replacing a traditional indoor heating system with a heat pump could save as much as $948 a year.

But switching to a heat pump also requires a significant investment, often thousands of dollars. That’s why Dr. Modi recommended making the switch when it’s time to replace to your old heating and air-conditioning system.

Much of that upfront investment will be installation costs, but many states offer rebates to help offset that expense. The Database of State Incentives for Renewables and Efficiency is one place to search for programs in your area. Manufacturers and local contractors should be good sources of up-to-date information as well.