Sunday, December 5

How to Make Air Conditioning Less of an Environmental Nightmare | Environment


TOAt first glance, the 32 panels on top of a grocery store in Stockton, Calfornia, look like solar panels. But this facility is not designed to take advantage of the sun, but to challenge it. Coated with a film technology that reflects radiation from the sun, the panels, and whatever lies beneath them, can drop 15 ° F (8 ° C) below ambient temperature, even half the temperature. day, no need for electricity.

It’s “a fundamentally different way of achieving cooling and harnessing an untapped renewable resource,” said George Keizer, COO of SkyCool, the company behind the panels. “We are using the sky as this huge heat sink,” Keizer said, sending excess heat from Earth’s surface, through the atmosphere, and into outer space.

In the grocery store, the panels are used to cool the water that runs behind them, which is then piped to the condensers that run the store’s refrigerators. That lowers the temperature of the refrigerants inside, increasing efficiency and reducing annual energy consumption by 15%.

SkyCool technology has also been installed in bus shelters in Tempe, Arizona, to keep commuters cool while they wait.

“The long-term goal is to see if we can find ways to use the films or panels to replace an air conditioner,” said Eli Goldstein, the startup’s co-founder and CEO.

SkyCool cooling panels on the roof of a grocery store in Southern California.
SkyCool cooling panels on the roof of a grocery store in Southern California. Photography: SkyCool

Extremely hot weather kills about 700 people in the US each year – more than hurricanes and floods combined – and a estimated 356,000 worldwide.

Air conditioning is the most obvious immediate response to dangerous global warming. It is also making it worse.

Air conditioners use more electricity than any other appliance in the home. They consume 10% of the world’s electricity (along with electric fans) and release powerful gases into the atmosphere that warm the planet. On the hottest day of the year in some parts of the US and the Middle East, 70% of peak residential electricity demand is for cooling spaces.

As global temperatures rise and heat waves become more common and deadly, the demand for air conditioners is increasing, especially in emerging economies like India, China and Indonesia.

The International Energy Agency (IEA) Dear that the global demand for space cooling will triple by 2050. The growing demand for cooling is “one of the most critical energy problems of our time, ”according to the 2018 IEA report, which concludes that to keep people cool without spiraling energy demand, the answer“ first and foremost ”is to improve the efficiency of air conditioners.

But that is not all that is needed. To moderate the effects of dangerous heat without further heating the world, a spectrum of solutions will be required, from more efficient ACs to shadier streets to new technologies that fundamentally change the way we stay cool.

New trees planted along the Valley Metro Rail in Phoenix, Arizona.  There is little shade in the neighborhood and the heat can be 20 ° F hotter than in other parts of the Phoenix metropolitan area.
New trees planted along the Valley Metro Rail in Phoenix, Arizona. There is little shade in the neighborhood and the heat can be 20 ° F hotter than in other parts of the Phoenix metropolitan area. Photograph: Caitlin O’Hara / The Guardian

Solving the air conditioning conundrum

Most ACs are relatively cheap and extremely inefficient. The energy performance standards that machines must meet don’t come close to maximizing their potential, said Iain Campbell, principal investigator at the Rocky Mountain Institute, a sustainability nonprofit, and 95% don’t exceed the bare minimum.

Another big problem with air conditioners is that they leak hydrofluorocarbon refrigerants (HFCs), powerful gases that warm the planet and a major contributor to global warming, into the atmosphere. The most widely used, R-410A, is more than 2000 times more powerful than carbon dioxide.

As the machines operate, the refrigerant travels in tubes between low- and high-pressure areas, turning into a gas as it absorbs heat from inside and releases heat from outside as it condenses back into a liquid. In its gas form, HFCs can leak through pipe joints (a typical residential unit can lose 10% of its refrigerant each year) or they can be completely released if an air conditioner is disposed of without properly draining it.

In 2018, the Rocky Mountain Institute launched the Global Cooling Award, offering a $ 1 million prize for new residential refrigeration technology five times more efficient and less polluting than today’s standard machines, it costs no more than double for consumers and can be installed in existing homes.

The two winning prototypes, announced in April and produced by two of the world’s largest refrigeration manufacturers, Daikin and Gree, function essentially the same way as current air conditioners, but are designed with better sensors and controls and are configured to use more environmentally friendly refrigerants. than those found in standard residential air conditioning units. They have also added features, such as engineering to remove excess moisture from the air to make it easier to cool (it takes more energy to heat humid air).

The winners say they will bring their designs to market by 2025. But until lawmakers in the US and abroad raise the floor on efficiency standards for air conditioning units, Campbell said, there is no clear way. for consumers to discern the difference between these new machines and those that are less efficient and have a much greater climate impact.

Mechanical engineer Vince Romanin realized that few consumers research the efficiency of specific air conditioning or refrigerants before buying, so he markets his AC technology on user experience, rather than environmental credentials.

“There are about 50 million people in the US with window air conditioners, and almost everyone hates them,” said Romanin, CEO of Gradient. Set up to straddle the windowsill, with the noises outside and the tech nestled under the window, Gradient’s machine isn’t “loud and ugly,” Romanin said, and it doesn’t block the view.

Gradient uses a low emission refrigerant packaged in factory sealed leak proof tubes. They’ll hit the market next year, it’s two appliances in one – the heat pump system that replaces hot air with cold in the summer works in reverse to turn it into a space heater in the winter.

An image of Gradient's air conditioning unit on the exterior of a building.
Gradient’s air conditioning machines straddle the windowsill and promise more efficient and less climate-damaging technology. Photography: Gradient

Campbell is excited about the potential of new materials to further drive cooling technology. Cooling award finalist Transaera is developing a “novel sponge-like” material that could improve the efficiency of air conditioners by passively sucking moisture out of the air. But until governments impose standards that rate ACs on how efficiently they reduce humidity, Campbell said, manufacturers have no incentive to include the technology in their products.

Irish cleantech company Exergyn is among the developing systems that replace damaging and leaking refrigerants with solid materials that contract and relax as they absorb and release heat. Solid-state refrigerants have “significant promise,” Campbell said, but they need more testing to show that they can last that long.

Design for heat

Better air conditioners alone can’t solve the growing heat crisis, but they are an important part of the puzzle, Campbell said, especially for growing urban populations around the world.

There are many other things that you would ideally do first, he said. That includes designing buildings that use less energy, have better ventilation, and are better insulated from heat.

“If you want to cool people down, you have to provide shade, period,” said V Kelly Turner, assistant professor of urban planning at UCLA’s Luskin School of Public Affairs. Whether in the form of trees or canopies, people’s bodies must be protected from the direct heat of the sun.

There is also the indirect effect of the sun that heats physical surfaces, such as streets and buildings. In cities, where the urban heat island effect can raise the temperature by as much as 20F (12C)Simply painting ceilings white can reflect enough sunlight to reduce heat by a few degrees.

A dozen US cities require or encourage the use of light-colored roofs in new construction, and dark roofs were installed in August. forbidden in the southwestern suburbs of Sydney, Australia, where new rules require that every backyard must have a tree.

The fundamental issues that make cities hotter need to be addressed, Turner said. But “we will need some air conditioning because [without it]”You can’t cool the core temperature enough if it’s exposed to really extreme heat.” That’s especially important, he emphasized, for vulnerable people, including outdoor farm and construction workers, children, the elderly and low-income renters, who not only need access to cooling centers on the hottest days. , but also air conditioning in their homes. (Most places in the US, he said, have laws that limit how cold an apartment can get, but none that prevent landlords from allowing homes to get dangerously hot.)

People at a cooling center at Kellogg High School in Portland, Oregon.
People at a cooling center at Kellogg High School in Portland, Oregon. Photograph: Michael Hanson / AFP / Getty Images

The Cooling award points to air conditioning, that last necessary element. “If your living space is a very small apartment in a mid-rise tower and you have six family members living there and the temperature in the summer peaks at about 120F, 130F, you are not going to say, ‘Well I need to insulate my apartment, or I need to put in some shade, ‘”Campbell said. “You’re thinking, ‘I need a damn conditioner so we can all sleep at night.’

People will continue to buy air conditioners, he said, so we must offer them better, safer and cleaner devices, and legislators must impose regulations that remove less efficient options from the table: “We can do better than this. And we are doing our citizens a disservice when we let them buy something that is so expensive to operate and so polluting that cooling actually increases global warming. “


www.theguardian.com

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