If you want to ditch your gas furnace and heat your home more cleanly and efficiently, you need to scale up one of your kitchen appliances. The first option is “electric resistance heating,” better known as a space heater, which acts like a giant toaster to warm a room instead of bread. The second is a heat pump, which extracts warmth from even freezing outdoor air and pumps it indoors, like a refrigerator moves heat from inside the box to the kitchen. (That’s why the back of your fridge feels warm, by the way.)

Energy experts say that to bring down greenhouse gas emissions and improve human health, we need to replace toxic gas furnaces and boilers with heat pumps ASAP. Less talked about, though, is that we also need to replace those giant toasters with giant reverse refrigerators, which would make homes more comfortable and more efficient, and therefore cheaper to heat.

According to a new report from the nonprofit energy group RMI, one in five homes in the United States is heated primarily with electric resistance heating. Replacing those devices with heat pumps would save households an average of $1,530 a year, or $20 billion annually across the country. (The calculations included only single-family homes, not multifamily units like apartment buildings.) At the same time, demand on the electrical grid would fall significantly, while total carbon emissions from homes making the switch to heat pumps for climate control and water heating would plummet by about 40 percent. “There’s a lot of benefits to the grid, which translate to lower rates as well,” said Ryan Shea, a manager in RMI’s carbon-free buildings program. “Then, of course, there’s using less energy.”

Electric heat pumps work their magic with a trick of physics: By changing the pressure of refrigerants, they draw warmth from outdoor air or liquids coursing underground, then bring it indoors. (In the summer, the process reverses, cooling an indoor space like a traditional air conditioning unit.) They’re ultraefficient because unlike a furnace or space heater — which generate warmth by burning fossil fuels or using electricity — these appliances simply transfer heat from one place to another. Accordingly, heat pumps have a “coefficient of performance,” or COP, of around three, meaning they produce three units of heat for every unit of electricity used. In other words, they’re 300 percent efficient. That’s three times as efficient as electric resistance heating, which has a COP of one, while even the most efficient gas furnaces operate well below that.

In all kinds of homes, heat pumps are replacing electric resistance heating or gas furnaces. If you don’t have ducting, heat pumps come in units that embed in walls to exchange between outdoor and indoor air. If you have ducting, an indoor unit replaces the furnace and connects to an outdoor one, which exchanges the heat. If you also have an AC unit that has reached the end of its life, subbing in a heat pump will give you both cooling and ultraefficient heating. “That’s kind of the right trigger point for a lot of people to start thinking about heat pumps,” Shea said, “is when their air conditioner needs replacing.”

The next generation of heat pump is targeting apartment-dwellers, too. A company called Gradient, for instance, has been working with building owners and public housing authorities to deploy its units, which slip over window sills like saddles and plug into a standard wall outlet. The appliance can swap in for old window AC units, giving tenants clean heating, not just cooling.

The idea is to quickly and cheaply deploy these appliances in large buildings, without landlords having to retrofit each unit if they, say, get rid of the structure’s central fossil-fuel boiler. Gradient says that in less than two weeks, it installed 277 of them in a Providence, Rhode Island public housing development that previously used electric resistance heating. “It is very straightforward and a huge energy win for them,” said Vince Romanin, the company’s founder and chief technology officer. “You’re not just saving money. You are providing a dramatically better service, because you’re adding cooling.”

Still, the RMI report notes, the U.S. builds nearly 1.5 million homes each year, 200,000 of them with electric resistance heating. It also installs a million AC units annually in homes with electric resistance heating, when those could instead be heat pumps that’d save occupants money. The trick, then, is for policymakers and utilities to incentivize these efficient appliances with rebates and the like. That’s what helped Maine reach its goal of installing 100,000 heat pumps two years ahead of schedule — by next year, it hopes to install 175,000 more.

The U.S., though, can’t simply replace all of its furnaces and space heaters with heat pumps and call it a day, energy experts said. It must happen alongside a push to make homes more efficient, like by installing proper insulation and double-pane windows. That is, a home needs to retain more heat in the winter and cool air in the summer, so a heat pump would need to run less. “Step one, don’t burn fossil fuels in your home, basically,” said Gernot Wagner, a climate economist at Columbia Business School, who wasn’t involved in the new report. “Step two: insulate, insulate, insulate. And both of those go hand-in-hand.”

The grid, too, needs upgrades if heat pumps are to reach their full potential. For one, ideally you’re powering them with electricity coming entirely from renewables like wind and solar, otherwise you’re still burning fossil fuels to warm homes. (Though to be clear, because heat pumps are so efficient, this is still better than sticking with gas furnaces.) And two, heat pumps join electric vehicles and induction stoves in increasing demand on the grid. Utilities are already making upgrades to handle all this electrification, like installing huge battery banks to store renewable energy to use when the sun doesn’t shine and wind doesn’t blow. They’re also experimenting with vehicle-to-grid technology, or V2G, which allows EVs to send power to the grid when demand is highest.

If the U.S. is really going to wean itself off fossil fuels, it needs all these systems to work in concert: More renewables, more batteries, fewer giant toasters.

This story was originally published by Grist with the headline American homes need heat pumps, not space heaters on May 5, 2026.

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