Heat pump investment in the United States has dropped by 4 percent in the past two years, even as sales of EVs have almost doubled, according to data from MIT and the Rhodium Group. In 13 European countries, heat pump sales dropped nearly in half in the first half of 2024, putting the European Union off-track for its climate goals.

“Many many markets are falling,” said Paul Kenny, the director general of the European Heat Pump Association. “It takes time to change people’s minds about a heating system.”

Heat pumps — essentially air conditioners that can also work in reverse, heating a space as well as cooling it — are crucial to making buildings more climate-friendly. Around 60 percent of American homes are still heated with furnaces running on oil, natural gas, or even propane; to cut emissions from homes, all American houses and apartments will need to be powered by electricity.

The European Union hopes to install 60 million heat pumps by 2030 — at the current rate of install, they may only get three-quarters of the way there.

In the United States, experts point to lags in construction, high interest rates, and general belt-tightening from inflation. Lacey Tan, a manager for the carbon-free buildings team at the clean energy think tank RMI, says that heating systems follow a regular pattern — they need to be replaced at least every 15 years or so. So installations occur cyclically, every 15 years after a building boom.

According to data from the U.S. Department of Housing and Urban Development, the last major spike in new home construction was in 2005, followed by a the 2008 housing crash. That means the biggest wave of upgrades for those homes has already passed; the homes being upgraded now were built during the housing slump.

“There is a period where sales slump, because it’s just how it lines up with people doing change-outs and retrofits,” Tan said. “And I think we’re in that period.”

Cora Wyent, director of research for the electrification advocacy group Rewiring America, also points to the fact that fewer buildings are being built. Heat pumps generally make up a larger share of new home construction.

But, she added, heat pumps are still growing as a share of overall heating systems, gaining ground on gas furnaces. In 2023, heat pumps made up 55 percent of all heating systems sold, while gas furnaces made up just 45 percent. “Heat pumps are continuing to increase their total market share,” she said.

Homeowners may also run into trouble when trying to find contractors to install heat pumps. Barton James, the president and CEO of the Air Conditioning Contractors of America, says many contractors don’t have training on how to properly install heat pumps; if they install them incorrectly, the ensuing problems can sour consumers on the technology.

The Inflation Reduction Act’s tax incentives, he argues, target consumers rather than contractors — but contractors have to be willing to offer heat pumps for install.

“In a big part of the northern U.S., there haven’t been really incentives to push people to learn how to do it properly,” he said. “They’re not yet comfortable that it’s actually going to work for the climate.” While new heat pumps work well in cold climates, older models had a reputation for struggling when outdoor temperatures got too cold.

In the United States, low gas prices also make the economics of heat pumps more challenging. Gas is around three times cheaper than electricity — while heat pumps make up most of that ground with efficiency, they aren’t the most cost-effective option for every household.

In Europe, heat pump installers are also facing a wave of misinformation. Last year in Germany, the government proposed a ban on installing gas furnaces — the law, which was eventually watered down, became a central talking point for the emerging far right. Right-wing groups claimed that heat pumps cost up to 100,000 euros (nearly $109,000) and only worked if homes had underfloor heating.

In the first half of 2023, contractors sold 1.44 million heat pumps in Europe — in the first half of 2024, that number dropped to just 744,000.

Kenny, of the European Heat Pump Association, points to those far-right protests — as well as falling gas prices. In 2023, with the invasion of Ukraine, natural gas prices spiked and Europe pivoted quickly away from the fuel. Now, gas prices have come down, undercutting the benefits of switching to electricity. Europe as a whole gets about 40 percent of its electricity from renewable sources, and just 20 percent from gas. At the same time, countries like Italy and Poland cut their subsidy rates, also eliminating some of the cost savings.

“Right-wing politicians and populist politicians need culture wars,” Kenny said. “And climate is an easy one.”

Heat pumps represent one of the tricky problems for the energy transition — even with government policies and subsidies, many parts of the move to clean energy will require individual people to make changes to their lives. According to the International Energy Agency, the number of heat pumps will have to triple by 2030 to stay on track with climate goals.

The only way to do that, experts say, is if incentives, personal beliefs, and technology all align.