Europe is overheating. This climate

The United Kingdom declared a national emergency this week during a historic heat wave that's melted runways, snarled train travel and shattered temperature records. The devastation has been particularly acute in a country like England, where 95 percent of the population lacks air conditioning.

Amid that, the British government has provided grant money to a little-known solution: heat pumps.

Bearing a misleading name, heat pumps are two-way air conditioners that move warm air from inside a home to the outside, keeping dwellings cool in hot months. In winter months, they do the reverse, taking heat energy from outside and pushing warm air in.

Energy officials, lawmakers and scientists tout the devices as inexpensive, energy-efficient systems that significantly reduce greenhouse gas emissions over traditional heating and cooling devices.

Estimates show that 90 percent of Japanese households use heat pumps to heat and cool homes, contributing to a 40 percent drop in the country's electricity consumption over the past decade. In Italy, the government effectively pays citizens to use the technology; homeowners can get 110 percent of their heat pump cost reimbursed.

But the devices lack popularity in parts of the United States and Europe because of low public awareness and high installation costs. The United Kingdom fell far short of its yearly heat pump installation goals in 2021.

Energy experts point to a couple of reasons heat pumps haven't entered the mainstream. First is the name, which makes it difficult for people to recognize that it heats and cools. "It is confusing," said Corinne Schneider, the chief communications officer for CLASP, an energy nonprofit.

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The high price of installation — systems can cost upward of $10,000 to buy and install — is also a hurdle for many users.

But with a heat wave forcing people to find ways to cool their homes, as Russia's war in Ukraine sends energy prices soaring, experts say heat pumps are a natural solution: an all-in-one system that cools during heat waves and reduces reliance on gas in the winter.

"It's a home comfort issue. It's a climate issue. It's a security issue," said Alexander Gard-Murray, a climate change researcher and economist at Brown University's Climate Solutions Lab. "Any one of them would be enough to move aggressively on heat pumps, but taken together I think the evidence is insurmountable."

The technology that undergirds heat pumps can be traced to the 1940s, when American inventor Robert C. Webber created a prototype copper-tubed heating unit in his basement. Over the years, Webber's creation inspired the core technology that allowed modern refrigerators to transfer heat out the back of a refrigerator, keeping the inside cool.

There are two main types of heat pumps. In warm months, air-source heat pumps suck out hot air from a room, blow it over a coil and cycle it through a refrigerant so cold air comes back inside. In cold months, the pump captures heat energy from air outside and cycles it through the machine to warm it and blow it inside. These pumps are similar in size to central air conditioning units.

Ground-source heat pumps transfer heat stored in the Earth into a building during the winter and transfer it out during the summer. These are less common and more costly than air-source options.

One of the most common complaints about heat pumps, experts said, was that they would stop providing heat on very cold days. But advances to heat pump compressors have made them more efficient, cost effective and successful at providing heat in colder temperatures.

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As heat pumps have improved, lawmakers and policy experts have tried to make the devices more mainstream. In the United States, a tax credit program provides about a $300 rebate for people transitioning their homes to heat pump technology. Amid Congress's stalled climate agenda, one proposal increases the incentive to $600. States and local utilities also have their own rebate programs.

The benefits to pocketbooks and the climate are reportedly significant, climate experts said.

In the United States, about 16,000 air conditioning units are installed daily on average. Researchers from CLASP and Harvard University predicted that if over the remaining decade, all houses installing central air conditioners bought a subsidized heat pump instead, consumers would save approximately $27 billion on heating and cooling bills, while decreasing greenhouse gas emissions by 49 million tons of carbon dioxide by 2032.

Researchers note much of the savings is due to a heat pump's ability to heat homes up to 50 percent more efficiently than furnaces and water boilers. Schneider of CLASP said Europe's heat wave is an opportune time for heat pump technology to become more mainstream, since many are buying air conditioners for the first time.

Other researchers note the stakes are high. "Every day that [people] fail to install as many heat pumps as physically possible, it means they’re locking in more dependence on [Russian President Vladimir] Putin and Russian gas this winter," said Gard-Murray of Brown University.

Sam Calisch, a heat pump expert at Rewiring America, added that because climate change is making heat waves more prevalent, cooling devices should be low emissions.

"More and more places that didn't used to have air conditioning more broadly are getting it," he said. "So every time this happens, we need to be thinking about heat pumps because that allows us … to delete some of the fossil fuel demand that we currently have."

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Because heat pumps cost a lot, spending the money might seem difficult. And because most people purchase air conditioners and heating units when they’re forced to, they often have little time to decide what to buy, Schneider said. They end up with what's common in stores or recommended by maintenance professionals.

"If you are in a heating or cooling emergency … you are going to take whatever's in stock," she said. "There needs to be a way for HVAC installers to increase their stock of this technology and to know about it."