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One of the most powerful weapons you can wield to fight climate change is … an appliance. A heat pump is a fully electric device that transfers warmth from outdoor air into a building, then reverses in the summer to act like an air conditioning unit. It’s much more efficient than burning planet-warming gas in a furnace, and will save the average American household more than $550 a year on their utility bill, according to one estimate.
Emphasis on average. Every American home is different in size and energy efficiency, and the US hosts wildly different climates that determine how a heat pump operates. But theoretically, what would happen if every US household got a heat pump? According to a new study in the journal Joule, it could slash the emissions in the residential sector by a staggering 36 to 64 percent, and cut overall US emissions by 5 to 9 percent.
Those heat pumps would be cost-effective even without subsidies in 65 million American homes, the modeling found. But in reality, the feds and individual states are already scrambling to reduce the costs of heat pumps, making adoption increasingly affordable. The Inflation Reduction Act of 2022 provides thousands of dollars in rebates or tax credits to install one. Just last week, the feds announced $63 million to supercharge the domestic manufacturing of heat pumps, on top of the $169 million they announced for the same purpose back in November. And earlier this month, nine states teamed up to get heat pumps into as many homes as possible ASAP.
Heat pumps are already outselling gas furnaces in the US, in part because the devices are now so efficient that they can extract warmth from even freezing outdoor air: Last year, frigid Maine announced that it’d hit its goal of installing 100,000 new heat pumps two years ahead of schedule. For when it gets really cold, some heat pumps come equipped with backup electric resistance heating, which works like a space heater. Overall, heat pumps are essential for decarbonization because they’re electric, so you can run them on a grid increasingly powered by renewables like wind and solar.
This new study modeled the whole housing stock in the US—structures like single-family homes, manufactured homes, and multifamily buildings. The modeling considered the size of the structures, as well as their “leakiness,” or how thoroughly they’re insulated. A home’s location is also important, of course, as a heat pump will have to work harder through a New England winter than a Southern California one. Cold-climate heat pumps are more expensive than your more basic temperate version, because they need to be more advanced and efficient to extract enough warmth from freezing outdoor air.
Because no one knows exactly how the grid will evolve in the coming years, the researchers considered different scenarios for how renewables will proliferate: If heat pumps are running more on wind- and solar-generated electricity, you’d get a greater reduction in emissions than if they were running on energy from natural-gas power plants. Overall, the researchers wanted to know if heat pumps could reduce emissions all across the US, no matter the climate.
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“The answer ended up being, yes, in all US states, on average heat pumps will reduce greenhouse gas emissions,” says Eric Wilson, a senior research engineer at the National Renewable Energy Laboratory and the lead author of the new paper. “Even if it’s a relatively low-efficiency heat pump that relies on electric resistance heating during the coldest times, and even if it’s the most pessimistic grid scenario that has prices for wind and solar being higher than their current trajectory has been.”
Because a heat pump can be reversed to provide cooling, getting more of the devices into homes could also improve public health during the summer, the study notes. That is, with a heat pump, a home that has never had AC now has a way to ensure comfortable indoor temperatures. That’ll be all the more critical as outdoor temperatures march relentlessly upward, especially in cities, where the built environment absorbs and slowly releases the sun’s energy. The tricky bit is that even though a heat pump can be more efficient at cooling than a traditional AC unit, its operating cost during the summer may surprise a household that has never had AC before.
It’s important to note that a household will get the most out of a heat pump if it also opts for better insulation. If you have double-paned windows, for instance, less of that indoor heating or cooling will escape in the winter or summer. That sort of insulation comes with its own upfront cost, sure, but reduces the upfront cost of the heat pump by thousands of dollars, the new study finds: If your home is sealed nice and tight, you’ll require a smaller, less expensive device to provide proper warming. “I worry a little bit about people putting in heat pumps in very poorly insulated homes, and just not being comfortable,” says Wilson. (To that end, the Inflation Reduction Act provides 30 percent off the cost of insulation. The legislation also offers thousands of bucks to upgrade your home’s electrical system, which may be required to accommodate a new heat pump.)
The study further notes that if deploying lowest-efficiency heat pumps, energy bills could increase in 39 percent of households, but that drops to 19 percent if they also reinsulate. (This is based on state-average energy prices from the winter of 2021-2022.) When using higher-efficiency heat pumps, only 5 percent of households could see an increase in their energy bills. The upfront cost of this insulation or higher-efficiency heat pumps could be offset by financial incentives, the study says, like those provided by the IRA.
This modeling isn’t predicting the future, but calculating scenarios for how the adoption of heat pumps could unfold in the US. In the coming years, the heat pump industry could well generate surprises—the good kind—especially as the US invests hundreds of millions of dollars into domestic production. “What are the efficiency improvements, the surprising innovations, the leaps here that one can only get when you in fact start deploying these at scale?” asks climate economist Gernot Wagner of the Columbia Business School, who wasn’t involved in the paper.
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The new research is modeling factors that we know of, but positive developments could lower the cost and increase the proliferation of heat pumps faster than anyone anticipated. Heck, IKEA is offering heat pumps in Sweden now.
In the US, a company called Gradient has developed a heat pump (shown above) that slips over a window sill, targeting those homes and apartments without existing ducting. Whereas a ducted heat pump for a single-family home requires a technician to install, Gradient says a consumer can install their device in about 30 minutes. It’s working with the New York City Housing Authority to install 10,000 units in buildings heated with old-school radiators. “Most of them have to provide their own cooling, and so they get the added benefit of also having this system cool,” says Vince Romanin, cofounder and CEO of Gradient. “I think we’ve pretty effectively shown that this is cheaper than the hardware they were using before to install, and cheaper to operate.”
As the country electrifies—with heat pumps replacing gas furnaces and electric vehicles replacing gas-guzzlers—demand for electricity will grow. Utilities will meet that demand with ever more solar and wind generation, and be able to store energy in giant batteries for when the wind doesn’t blow and sun doesn’t shine.
An additional challenge is that this increased demand for electricity will sometimes be concentrated: If everyone gets home from work and switches on their heat pumps, that suddenly spikes demand for hours. But if they can manage for their homes to be a few degrees cooler or hotter, they can run their heat pumps less, which would reduce demand. Utilities are also encouraging customers to “precool” or “preheat” their homes, shifting that demand to a different time of day, especially if they’ve got good insulation and can hold onto that cooling or heating. And with the proliferation of smart thermostats and heat pumps, utilities can even remotely tweak the temperature in a home—with the permission of the homeowner, of course.
So yes, more heat pumps will demand more electricity, but the grid will evolve to accommodate that, and in a clean way with renewable generation. It’s not a matter of if heat pumps will replace gas furnaces in American homes en masse, but how quickly they’ll do so.
