With more heat waves in our future, researchers say we need to look at clean cooling

As cold temperatures are once again upon us, it's unlikely many Canadians are thinking about heat waves. But Canadians increasingly have to deal with them, and it's virtually certain next year won't be any different.

In 2021, a heat wave stifled parts of B.C., killing roughly 600 people. As a result, many people rushed out to buy air conditioners, and the government even created a program to provide free AC to low-income families. 

The effort to stay cool in a warming world is a challenge. Our air conditioners are not only hooked up to energy grids that may be fossil fuel-intensive, but they often leak, emitting harmful greenhouse gases — the most concerning being hydrochlorofluorocarbons (HFCs) — into the atmosphere.

They also emit a lot of heat themselves.

So how do countries keep their citizens cool and safe as heat waves become more frequent and intense without increasing their carbon footprint?

The answer is called sustainable cooling.

What is sustainable cooling?

As the name suggests, sustainable cooling is about providing cooling that is clean. That could be "passive" cooling (such as planting greener areas in cities and on buildings), developing a renewable-heavy power grid or building air conditioners that are less harmful to the environment.

"We've got to make it accessible and environmentally sustainable, because currently, cooling accounts for seven to eight per cent of global greenhouse gas emissions, and it's the fastest-growing cause of global greenhouse gas emissions," said Toby Peters, a professor in cold economy at the University of Birmingham in England.

HFCs that leak from air conditioning units have an incredible global warming potential (GWP) — 14,800 times higher than CO2 over 100 years. A recent study found that if we continued along the business-as-usual path, HFCs could add 0.5 C of global surface warming.

When it comes to passive cooling, there are many examples. A "green" roof helps regulate a building's internal temperature and reduces both heating and cooling costs. There are also "white" roofs, where the tops of buildings are painted white in order to better reflect the sun's radiation and heat. 

It's a way of cooling used in the past.

"You've seen pictures of traditional Greek architecture, for example … you have these white-coloured buildings. There's a reason for that," said Tim Fox, an independent consultant on climate mitigation and adaptation based in Cornwall, England. 

There are other passive ways. Paul Huggins, associate director with the Carbon Trust, a global consultancy that helps companies decarbonize, notes that a building's orientation along with the use of facades and large overhangs are good ways to reduce the need for cooling. 

U.S. cities like Los Angeles are even using a coating on pavement that keeps it cool, which is important in urban centres that create warmer "heat islands" than the surrounding areas. Some cities are cooling their buildings with ice, such as the Goldman Sachs building and the Rockefeller Center in New York.

Technologically, there has been an increased effort to move away from HFCs. This refrigerant was initially used to replace chlorofluorocarbons (CFCs), which were depleting ozone — which protects all life from harmful ultraviolet radiation — over the South Pole.

But it became apparent HFCs were also harmful when it came to climate change and the atmosphere. 

This has led to a 2024 change to the Montreal Protocol — the 1987 agreement made by countries to phase out CFCs — called the Kigali Amendment, which will similarly phase out HFCs. 

Interestingly, the Global Cooling Prize was announced in 2018 in an effort to find ways of reducing the climate impact from air conditioners by at least five times. Two companies won in 2021, illustrating it can be done.

"As you were saving 80 per cent of the energy, you actually would get the saving back. It would be cheaper to operate," said Peters of the prize-winning designs. "So, if you look at the Global Cooling Prize, obviously, what we haven't yet seen is those technologies come to market."

But that does offer hope, he said.

Multiple impacts

At COP28 in Dubai, U.A.E., in 2023, more than 60 countries signed the Global Cooling Pledge, which aims to "reduce cooling-related emissions by 68 per cent from today by 2050, significantly increase access to sustainable cooling by 2030, and increase the global average efficiency of new air conditioners by 50 per cent."

The United Nations estimates that more than 2.4 billion workers around the globe are exposed to excessive heat, "driven largely by a fossil-fuel charged, human-induced climate crisis." Earlier this year, the World Health Organization found 175,000 people die from heat-related issues annually in Europe — and that the number is set to skyrocket.

Insufficient cooling can also lead to food waste. 

According to the UN's Environmental Program, about 1.3 billion tonnes of food — roughly one-third of all food produced globally — is lost or wasted annually. If food waste was a country, it would be the third-largest greenhouse gas emitter, just behind China and the U.S.

Much of that waste is due to food that rots during transport. It's another reason nations and groups are calling for better cooling options, called a cold chain.

And it's not just about food.

"You want to deliver vaccines in Africa? You need a cold chain. You want to deliver food in Toronto? You need a cold chain," Peters said.

The biggest way we can reduce emissions is by getting on renewables, as we use so much energy in every facet of our lives, Peters said.

"You want to live in India or Dubai or Toronto? You need air conditioning. You want to talk over Zoom? You need cooling for a data centre. So it's critical infrastructure," he said. "The challenge is, how do we deliver access to cooling for all who need it, without the environmental damage that cooling currently does, and make it also resilient as well." 

According to a recent report from the UN Environmental Program, speeding up the adoption of passive cooling, increasing energy efficiency and refrigerant phase-down would have cascading positive effects. It would reduce electricity use, reduce spending on equipment and reduce power-sector investments by more than $8 trillion US in developing countries over the next 25 years. 

Furthermore, scaling up sustainable cooling across developing countries could cut consumers' electricity bills by roughly $5.6 trillion over the same period. That's why many say there's good financial reason to adopt sustainable cooling.

Peters said he's optimistic about sustainable cooling, but that the thinking needs to change.

"We need to recognize the critical role of cooling going forward and move away from just thinking in terms of electricity, energy efficiency, and understand that as we transition to renewable [energy sources], we want to rethink the whole approach."