Mike De Socio is a CNET contributor who writes about energy, personal finance, electric vehicles and climate change. He's also the author of the nonfiction book, "Morally Straight: How the Fight for ...

Heat pumps have annually outsold gas furnaces for several years now, and with the recent introduction of more high-efficiency, cold-climate, air-source heat pumps, that trend is likely to continue.

Heat pumps function similarly to refrigerators or air conditioners, which take warm air from one space and send it to another. In the winter, a heat pump transfers heat from the outdoors inside and, ...