The air conditioning has a climate problem. New technology could help.

This week, Californians were reminded of one of the most vexing paradoxes of global warming. With temperatures above 110 degrees Fahrenheit in some areas Tuesday night, hundreds of thousands of state residents received beeping alerts to warn them that the power grid, straining under the weight of millions of air conditioning units, was about to collapse. Save power now, the text warned, or face rolling blackouts.

Consumers were spared and the state’s power grid managed to escape a record hot day relatively unscathed. However, as temperatures rise globally, more people will need to install air conditioners. But as currently sold, AC units can actually make global warming worse: On hot days, they draw tons of electricity from the grid, and their chemical refrigerants can accelerate global warming.

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That’s why researchers and startups are hoping to create new, cutting-edge AC units. AC technology has only seen “incremental improvements over the last 100 years,” said Ankit Kalanki, director at Third Derivative, a climate technology accelerator co-founded by energy think tank RMI. “There has been no change in innovation.”

The good news is that companies are rushing to develop more efficient ACs. The question is whether they will be ready in time.

In the coming decades, global demand for air conditioning is expected to skyrocket. According to the International Energy Agency, the number of AC units in buildings worldwide should reach 5.6 billion by 2050, up from only about 2 billion units today.

But if air conditioning performance is not renewed, all these ACs will put an unprecedented strain on the power grid. Air conditioners and electric fans already account for about 10 percent of electricity consumption worldwide. On extremely hot days, AC efficiency drops, as the units have to work harder to transfer heat from indoors to outdoors. During a heat wave, millions of people come home and turn on their AC at the same time, sometime between 4 p.m. and 9 p.m. When that happens, air conditioning can account for a whopping 60 to 70 percent of electricity demand and shake grids like California’s.

Meanwhile, the key ingredient in modern air conditioners—chemicals known as refrigerants—has been wreaking havoc on the atmosphere for decades. ACs work by exposing a liquid refrigerant, a chemical with a low boiling point, to warm indoor air. This heat causes the refrigerant to evaporate into a gas, cooling the air. A compressor then turns the refrigerant into a liquid and repeats the process.

The problem is that refrigerants can leak from air conditioners, both during use and, more commonly, when ACs are discarded. Early ACs were largely made with chlorofluorocarbons, or CFCs, which were responsible for one of the first real global climate stresses: the hole in the ozone layer. CFCs were phased out by the 1987 Montreal Protocol, an international treaty to deal with the destruction of the ozone hole, and were eventually replaced by hydrofluorocarbons, or HFCs.

But HFCs have their own problem – they are greenhouse gases that, in the short term, are thousands of times more potent than carbon dioxide. An amendment to the Montreal Protocol aims to phase out HFCs by the mid-2040s. In the meantime, however, they still contribute to global warming.

There are many ways to make existing AC technology more efficient. Some newer AC units use different refrigerants, such as one known as R-32, which has less global warming potential than other hydrofluorocarbons and also requires less energy to compress, saving electricity. Other units use a technology known as “variable speed compressors”, which allows the unit to operate at different settings. The compressor can speed up if it’s 100 degrees Fahrenheit and inflate, or slow down if it’s only 85 degrees. This can help save on electricity and utility bills.

And more advanced models are just around the corner. Kalanki was one of the leaders of an RMI initiative known as the Global Cooling Prize, which rewarded manufacturers who could produce affordable AC prototypes that would be at least five times better for the climate than existing models. Two companies received the award together: Gree Electric Appliances and Daikin Industries. Both used traditional vapor compression technology, but with improved refrigerants and clever designs that could change settings depending on outside temperatures.

Other companies, startups and researchers are investigating whether they can eliminate vapor compression altogether. A start-up called Blue Frontier uses a liquid that sucks moisture from the air and stores it in a tank to control the temperature. According to the company, this approach could save up to 60 percent of the electricity needed to run an AC year-round. And a team of researchers at Harvard University has developed a prototype air conditioner they call coldSNAP. The prototype uses no refrigerant, but instead uses a special coating on a ceramic frame to evaporate water to cool the interior without adding moisture to the air. “Because we don’t have the vapor compression system and the energy of trying to release and compress the refrigerants, the energy consumption of these systems is much, much lower,” said Jonathan Grinham, one of the researchers on the project.

Some of these new designs may take years to reach the market, and when they do, they may still be more expensive than conventional ACs. But in the meantime, Kalanki says, there are still plenty of options to buy a more efficient AC unit. “There are technologies that are two to three times more efficient than the most common ACs on the market today,” Kalanki said. “The challenge is that adoption is very low.” Most consumers, he argues, simply look at the sticker price on an air conditioning unit and ignore the fact that buying a more expensive unit up front could save them money in the long run.

He recommends buyers look at three things when looking at an AC unit: the type of refrigerant used, the rated efficiency, and whether or not the unit has a variable speed compressor. These metrics can tell consumers whether their unit is likely to cost them thousands of dollars in electric bills and whether it will unnecessarily add to the problem of climate change.

Ultimately, he added, the government needs to set stricter performance standards for air conditioners so that all air conditioners on the market—not just the highest-end ones—are efficient and safe for the planet. “There are floor regulation regulations for air conditioners,” he said. “But this floor is a little too low.”

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