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Cool techniques beat heat during Games

                                Cooling “kaze no obisashi” eaves in the upper area of the National Stadium, the main venue of the Tokyo Olympics, circulate air to carry away heat and moisture from inside the stadium.


    Cooling “kaze no obisashi” eaves in the upper area of the National Stadium, the main venue of the Tokyo Olympics, circulate air to carry away heat and moisture from inside the stadium.

TOKYO >> The coronavirus isn’t the only issue Japan is tackling to keep the Tokyo Olympics safe. Another threat is the summer heat, and various efforts have been aimed at protecting athletes, staff and visitors from suffering heatstroke.

Here are a few ways, big and small, that the Japanese are doing just that.

Architectural design

The National Stadium in Shinjuku ward, the main venue for the Olympics and Paralympics, was designed with an emphasis on alleviating heat.

“We designed the stadium by taking wind into consideration,” said Taisei Corp.’s Hisao Kawano, one of the companies involved in building the stadium.

Since air conditioning isn’t an option in a stadium, the design team focused on the southeasterly wind that intensifies in the area during the summer.

Large wooden eaves, “kaze no obisashi,” built in the upper stands, guide the wind into the stadium and allow airflow to carry away heat and moisture from the field and seating areas. In the winter the design blocks cold winds that blow from the northwest.

Kawano’s team divided the eaves into 17 sections and, through simulations, determined the appropriate spacing of the wood pieces for each section. The maximized ventilation also helps prevent spread of the corona­virus.

“A stadium reflects the times and society when it was built,” Kawano said.

Tradition and technology

“Uchimizu” — sprinkling a street with water to lower summertime heat — is a centuries-old cooling technique still widely practiced in Japan. Temperatures ease as the water evaporates.

Uchimizu became a popular theme in haiku poems and was depicted in ukiyo-e woodblock prints during the Edo period (1603-1867). Today it is used as a tradition to welcome guests.

A modern, high-tech version of uchimizu utilizes artificially generated mist, in which tiny water particles are sprayed to lower temperatures.

There is science in the size of the particles; if they are too large, people will get wet. Panasonic Corp.’s new misting system, installed at a plaza at a Tokyo train station, avoids the problem completely. Special nozzles generate tiny water particles that make people feel cool but not wet. According to the company, misted air feels about 12.6 degrees cooler.

The system has also been installed in Odaiba along Tokyo Bay, where the triathlon will be held.

“Spraying mist has a strong cooling effect that consumes little power,” said a Panasonic official. “We have high hopes that it will be suitable for the infrastructure of future cities.”

Made in the shade

In Tokyo’s summer heat, shade is an oasis.

Green Tokyo Kenkyukai has developed an online system called Tokyo Oasis that allows smartphone users to search for routes with plenty of shade and shadows so they can stay cool while walking.

The system’s database contains the heights of buildings and trees covering nearly 300 acres of the Otemachi, Marunouchi and Yurakucho districts in Tokyo to calculate shaded and shadowy areas every hour based on the movement of the sun.

When a user searches for a route to an “oasis spot” with abundant greenery and other restorative elements, a map will show a path that goes through shaded areas.

Meanwhile, Toray Industries is providing another way to stay shaded. The company developed Summer Shield, a triple-layered fabric for parasols that provides 100% light-shielding and 99% ultraviolet protection. Parasols made with the material have a cooling effect about 7 degrees greater than that of ordinary parasols, the company said.

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