Urban Transformation

What cities can learn from the cooling systems at the Tokyo Olympics

Tokyo 2020 Olympics: an athlete in the women's marathon splashes quarter on her face to cool down

At least 30 athletes at Tokyo 2020 were treated for heat-related illnesses. Image: REUTERS/Feline Lim

Jatinder Sidhu
Writer, Forum Agenda
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  • Sweltering heat and high humidity led to ‘feels-like’ temperatures of 40°C for many events at the Tokyo Olympics.
  • At least 30 athletes were treated for heat-related illnesses.
  • Cooling measures included solar-reflecting paint, wind-cooled buildings and wearable tech.

With concerns of 40°C heat and 80% humidity Japanese officials have sought for several years to allay fears that Tokyo, in mid-summer, would be too hot to host the Summer Olympics.

During the Games, the world watched as players and teams demanded that events be moved to cooler parts of the day. At least 30 athletes were treated for heat-related illnesses, including tennis players who withdrew from competition. Beach volleyball players complained that the sand was almost too hot to stand on. Swimmers said the water in Tokyo Bay (29°C) felt “as hot as soup”.

Organizers and designers of facilities have long known it would be a challenge. Tokyo temperatures gained 3°C over 100 years in part because the city acts as a heat island, trapping hot air.

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In mid-2019, a year before the games were due to be held, they brought in technology and design companies under the banner: Tokyo 2020 COOLING Project.

So what were the design features and measures to mitigate the effects of the heat?

Solar-blocking paint

Using a paint developed by NASA to keep astronauts cool, more than 100km of road surfaces were coated, with the effect of reducing temperatures by 8°C.

The move was meant, in part, to alleviate the heat facing marathon runners, but the event was moved to the northern city of Sapporo.

Stadium “designed for wind”


The focal point of the Olympics, the 68,000-seat Japan National Stadium was dubbed “the wooden stadium” for the amount of cedar and other wood panels used in its construction.

It’s been designed with giant eaves to encourage as much airflow as possible from outside, with a vast open roof providing shade, scores of coolers and fans, and 47,000 plants in and around the structure.

The organizers claim temperatures inside the venue are 10°C lower than those outside.

Misting machines

Mobile and fixed misting towers spraying water can cool the air by as much as 20°C, and were widely deployed.

They were even used to cool horses taking part in equestrian events. The drawback is that they require a lot of fresh water: almost 50 litres an hour.

a map showing the hear in Japan during the olympics
Athletes competing in Japan’s COVID-delayed Olympics faced stifling heat. Image: Japan Meteorological Agency

Air conditioners

Other measures included moving as many events as possible indoors, and then deploying more efficient air-conditioners.

This was a requirement because the Tokyo 2020 organizers declared they wanted “the greenest Olympics ever”.

The latest IPCC report on climate change underlines the urgent challenge facing governments to cut greenhouse gas emissions while living with increasingly erratic weather patterns.

The use of air conditioners and electric fans for cooling homes and workplaces already accounts for 10% of global electricity use, according to the International Energy Agency (IEA).

And it projects that electricity consumption for air conditioners will triple by 2050. That’s why the recent G7 meeting in England called for a doubling of the efficiency of cooling systems sold worldwide by 2030. Japan is at the forefront of some of these moves.

a chart showing the expected growth in demand for ir conditioning by 2050
The International Energy Agency says demand for air conditioning could triple by 2050. Image: IEA

Wearable tech

As well as urban design and cooling solutions, there is wearable tech. Many athletes in Tokyo trialled outfits with “technologies that could also be used for prevention, diagnosis and real-time monitoring of skin and core temperature”, according to the British Journal of Sports Medicine.

For the rest of us, there are solutions of the kind demonstrated at the opening and closing ceremonies.

Team USA wore Ralph Lauren-designed jackets with “a self-regulating personal thermal management device”. The company says the garment “disperses heat from the wearer’s skin through a sophisticated device that monitors and optimizes temperature and uses the same technology to cool the world’s most advanced computer systems”.


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And that, ultimately, may hint at the most efficient way to cool, or indeed heat, ourselves in the future.

As part of efforts to improve energy efficiency and reduce emissions research into localized thermal management (smaller spaces), and personal thermal management (clothing), is burgeoning.

In the US, heating, ventilation, and air conditioning (HVAC) account for about 13% of all energy usage. The US Department of Energy is funding research into both installed and wearable devices that regulate temperatures so that buildings can operate in wider temperature ranges while maintaining comfort levels.

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