Air conditioning worsens climate change. Here are some ways to fix it.


Although climatologists say humans can still avoid the worst possible effects of climate change if the economy shifts to carbon neutral activities as soon as possible, it is clear that the planet will continue to warm regardless of how fast we are. let’s achieve this goal. To some extent, humans will face a hotter and more dangerous planet. That means we’ll need to find sustainable ways to keep things comfortable at home, at work, and everywhere in between as temperatures rise.

The obvious solution to dealing with high temperatures is air conditioning, but current AC technology only makes climate change worse. Most designs require the use of refrigerants: chemicals that absorb heat and turn it into cold air after it passes through a compressor and evaporator. The most common AC refrigerants are hydrofluorocarbons (HFCs), but they are potent greenhouse gases, thousands of times more efficient at trapping heat than carbon dioxide.

We are therefore at an impasse at the moment: the more temperatures rise, the more our air conditioners are running at full speed. The more our air conditioning units operate, the more they contribute to climate change and, of course, to rising temperatures.

The EPA ruled earlier this year that the United States would reduce HFC production and consumption by 85% over the next 15 years. It’s the right move, but with the demand for air conditioning continuing to rise globally, we are pressed for time for air conditioning ideas that still keep us away from HFCs.

“What people are looking at are basically different molecules that are easy to break down and don’t quite have the greenhouse effect that HFCs have,” Mircea Dincă, professor of energy at MIT, told the Daily Beast.

One possible substitute, hydrofluoroolefins (HFOs), are already used for air conditioning in many vehicles and stay in the atmosphere much shorter than HFCs. But the initial cost of HFOs is high, and businesses just weren’t bothered enough to make the switch anyway.

Other possible alternatives include ammonia, propane, and carbon dioxide. But these solutions carry high risks: with propane, a leak can cause a fire. An ammonia leak itself could also be fatal to people.

A San Francisco-based start-up named Gradient has designed an air conditioner that uses a refrigerant called R-32, which is part of the HFC family but is a greenhouse gas that is less than half as harmful to humans. the atmosphere than the HFCs that we traditionally use for air conditioning. German researchers have designed a device that uses metal alloys to literally suck heat from the air, meaning no refrigerant is needed. It is, however, too early to say whether either of these solutions could lead to a new dominant form of CA.

Apart from the HFC issue, we also need to make the machines that cool our homes and workplaces more energy efficient to help fight climate change. According to Dincă, the reason air conditioners are so inefficient is that they not only have to cool the air, but also the water vapor in the air.

“What you should be cooling is basically the nitrogen and oxygen in the air, not the water. Water has a very high heat capacity, so it takes a lot of energy to cool the water, ”said Dincă. “It actually cools the air well below the temperature you need to feel comfortable, so it’s a huge waste of energy.”

Dincă said that one way to solve the problem is to simply remove water vapor, which is why he co-founded a company called Transaera which has designed very porous materials that can extract moisture from the air for that an air conditioner is operating. Whatever refrigerant your air conditioning unit uses, these types of materials could help make it much more efficient, which is good for the environment.

There are also low-tech ways to help keep our buildings cooler and get around the predicament of air conditioning. The United States is hampered by the fact that buildings often have very little ventilation, which would promote more natural cooling for homes and workplaces. Clark Bullard, a retired engineering professor and former director of the Department of Energy’s Conservation and Renewable Energy Policy Office, told the Daily Beast that Americans should rethink building designs more drastically.

“A long time ago in the United States,” Bullard said, “because electricity was cheap and air conditioning came on, engineers began to design buildings with windows that didn’t open, or with eight foot ceilings instead of 10 or 12 ”. foot ceilings where all the hot air had nowhere to go. These staid design habits have stuck with us for decades, even long after the threat of climate change became clearer.

We can’t redesign every building in the country to improve ventilation, Bullard said, but we could rethink how we design buildings in the future and upgrade buildings where we can. He says if you’re in an area where there’s not a lot of humidity, ventilation can go a long way in keeping things cool. One concept that could help are electrochromic windows, smart windows that can let heat in at certain times of the day and let heat out at other times, optimizing cooling according to changing conditions.

A historic Badgir located in Iran.

Alireza Javaheri

In the Middle East, where heat is obviously a major problem, simple but elegant engineering can do the trick. Wind catchers (called badgirs) are tall structures that sit on top of houses and direct the breeze into your house. These types of techniques could be used to help cool American homes without using electricity at all.

There is no question of staying indoors indefinitely just to stay cool, so we also need to think about how we will keep our outdoor spaces comfortable as the planet warms. There are also proven ways to achieve this goal.

“Trees are great air conditioners,” Bullard said. “They suck water out of the soil and evaporate it, so it can be 5 degrees or even 10 degrees cooler around a forest than it does in a field. This not only protects you, but they also have a lot of evaporative cooling. They cool the air because each leaf is a heat exchanger that evaporates water into the air.

Narasimha Rao, associate professor of energy systems at Yale, is optimistic about the power of natural environments to cool things down. “We need to have more urban greening, because cities are where most of the population will live for the next 30 years, and there is a heat island effect,” he told The Daily Beast. “We also need to care about the built form of cities to make them cooler. “

All of these solutions do not necessarily have to be massive overhauls of urban infrastructure. An easy way to combat the heat island effect (the heat swell that builds up in cities) is to simply paint things a lighter color. Dark colors absorb heat from the sun, so you can reduce the amount of solar energy a city absorbs by painting more things white or other lighter colors. This paint can be applied to roads, roofs and more to reflect sunlight. Researchers created a white paint earlier this year that reflects 98.1% of sunlight, which allowed it to reduce surface temperatures to 8 degrees below the air temperature during the day. More cities are turning to lighter paints as a cheap way to mitigate rising temperatures.

There are other lessons from the Middle East that could inspire the West to rethink cities to deal with rising temperatures. For example, instead of letting pedestrians walk the streets alongside cars – where the sun heats the asphalt to scorching temperatures – we could design narrow pedestrian lanes that provide shade and a funnel into the road. broken. Scientists have learned that small bodies of water, even fountains, can also help cool an area. The Moorish Palace of the Alhambra in Granada, Spain has kept things cool using this method since the 1300s.

None of these solutions is a silver bullet. And to some extent, people will have to accept that we will live in a warmer world no matter what we do. How intense the heat is and which places remain habitable will depend on the aggressive measures countries take to tackle climate change in the future.


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