Our descendants will look back on this time in human history with a mixture of confusion and disgust. Americans spend around 90 percent of their time in indoor spaces, which we heat by burning fossil fuels that also warm the planet and sully the air of our homes. Our descendants will be especially confused because for years we’ve had easy access to a cleaner, more efficient alternative: the fully electric heat pump.
At long last, though, the humble heat pump is exploding in popularity. Unlike a boiler or furnace, which burn fossil fuels to produce heat, this device transfers heat through an outdoor unit into the indoor space. (It looks a bit like a traditional air conditioner.) In the winter, a heat pump extracts heat from outdoor air, but it can be reversed in the summer to pump heat out, providing cooling. Exchanging heat in this way is much more efficient than generating it.
Last year, 4 million heat pumps were installed in the US, up from 1.7 million in 2012. Europe, too, is coming around to the heat pump, with sales increasing 28 percent in Germany in 2021 and 60 percent in Poland. That’s no small feat, given the global pandemic slowdown, and it’s just the beginning of growth, especially with Europe’s push for energy independence from Russia amid the war in Ukraine.
“Heat pumps are a few years behind electric vehicles but really deserve similar attention and could deliver very sizable reductions in emissions if we deployed them much more rapidly,” says Jan Rosenow, director of European programs at the Regulatory Assistance Project, an NGO dedicated to the transition to clean energy.
Here’s how heat pumps work, how governments can use them to reduce emissions, and how you can get your hands on one.
Moving Heat, Not Making It
A heat pump works on the same principle as a refrigerator, which keeps your food cold not by pumping cool air in, but by pumping warm air out. The heat you feel on the outside of the machine is actually being transferred away. Similarly, a heat pump can cool a building by moving hot air out. Or, in the winter, a heat pump can warm a building by operating as a sort of “reverse refrigerator,” extracting heat from even cold outdoor air and bringing it inside. (That’s putting it simply—the engineering involved is rather complex.)
“The air may be relatively cold, but it’s transferring heat from that cold air into your home,” says Randal Newton, vice president of engineering of Trane Technologies, which makes heat pumps. “Your refrigerator is cold, and it’s still transferring heat into your kitchen from that cold box.”
Home heat pumps can even run on the geothermal energy in your backyard. Instead of exchanging heat with the air, a geothermal pump uses plastic pipes buried in the yard to exchange heat with the land itself. (You don’t have to live on top of a hot spring; once you get four or five feet deep in the ground, it stays at a fairly constant temperature year-round.)