We are in a vicious cycle when it comes to climate control: The hotter the world gets, the more people want to use air conditioning—but using air conditioning also adds to global warming, which means more need for air conditioning. By one calculation, as more people around the world can afford to buy and use air conditioners over the next three decades, we’re on a path to add half a degree Celsius of global warming by the end of the century from air conditioning alone if the technology doesn’t change.
Two things make air conditioners particularly bad for climate change. “One, it’s a very energy-intensive piece of equipment, and two, the refrigerants that air conditioners use are highly potent greenhouse gases,” says Iain Campbell, a senior fellow at the nonprofit RMI, which worked with the Indian government and a clean energy initiative called Mission Innovation to launch the Global Cooling Prize, a competition that asked manufacturers to completely redesign air conditioners to shrink the climate footprint.
Today, the competition announced two winners with new prototypes for air conditioners that have five times less climate impact than the units that are on the market now. If scaled up, the technologies could help avoid 132 billion metric tons of CO2-equivalent emissions by the middle of the century.
The winning designs, from a major Chinese manufacturer called Gree Electric Appliances with its partner Tsinghua University, and Daikin, an Indian manufacturer that partnered with Japan’s Nikken Sekkei, use proprietary compressors designed to work with refrigerants that aren’t as polluting. A typical air conditioner now might have a refrigerant that’s around 2,000 times as potent as carbon dioxide, so if even a little escapes it has a major impact. One of the new designs uses a refrigerant that has a “global warming potential” of less than one, meaning it’s less impactful than CO2. The designs also optimize how the equipment cools or dehumidifies the air; if the temperature is already low enough but the room is still humid, the equipment can efficiently switch to only lower the humidity. One of the designs senses the outdoor air, so it can let in fresh air when it’s cooler outside; one design can also connect directly to a solar panel, which can shrink the amount of power the unit takes from the grid.
Even as countries are shifting to renewable electricity, it’s not moving quickly enough to keep pace with the demand for air conditioners from consumers in countries like India. In 2018, for example, a record 104 gigawatts of solar power was added around the world. But the same year, new air conditioners added more than 130 gigawatts of demand to the grid. “The growth in cooling is going faster than the growth in renewable solar energy,” says Campbell. “That was part of the idea of the prize: How do we make cooling less emissions-intensive so renewable energy can catch up, and we can actually have a chance to decarbonize cooling?”
The competition focused on “mini-split” air conditioners, units that connect to outdoor compressors, because they are the fastest-growing type of air conditioner. But similar technology could also be used for in-window air conditioners or central air conditioning systems.
The upfront cost of the new designs is higher than the standard alternative, but saves money over time because the efficiency of the system means consumers will save so much on energy bills. Rating systems like Energy Star will need to change to make the benefits clearer to consumers in a store, Campbell says. (Right now, ratings systems haven’t kept up with the best available products, so a mediocre product could the same five-star rating as something significantly better; he says that ratings systems should continue to evolve so that the best available tech gets the top score, and everything else ladders down from that.) Utilities may choose to offer financial help for consumers to buy the the air conditioners, since reducing power demand on the hottest days can help avoid brownouts and blackouts. Other policies like tax credits could encourage developers and apartment building owners to choose the new technology even though they won’t be paying for utilities.
Gree plans to bring its new design to market by 2025. It’s unlikely to have happened without the challenge in place, since policymakers tend to only raise minimum performance standards by tiny percentages. “In an environment where every couple of years those [standards] increase by 3-5%, they’re not looking and saying, ‘How do I increase the efficiency by 400%?'” says Campbell. “They’re saying, ‘Okay, my target is 3-5%.'” But they were capable of meeting the far more ambitious target. “They showed us that when you ask them the right question, industry can do this,” he says.