Average temperatures in Japan during summer are 30℃, on a lucky day they drop to 27℃. But on some days they might even reach 35℃. This is not that high in comparison to i.e. Arabic countries where it is often 40℃ or higher. The problem with Japanese summer is the same as in most of the Asian countries: it is the combination with high humidity. Additionally, big cities like Tokyo and Osaka have many concrete buildings, which makes the heat stuck more than in open spaces, where the wind can blow through.
In a measurement to fight against the hot summer, to prevent frequently occurring heat strokes at in a move towards a more environmental friendly Japan, the government in Japan introduced the “Cool biz campaign” in 2005. The idea is to set the air-conditioning to 28℃ and to allow business people to have a less strict attire. Apparently, “biz” stands for “business”, and focuses especially on the white-collar work field.
Cool biz principles are no tie, no suit jacket and if you are lucky even short sleeves shirt, additionally the air conditions rid set to 28℃. With this approach business people are thought to be able to survive an office at 28℃, which is not that cool, if outside it is boiling 30℃ or higher.
Many clothes brands such as Uniqlo and business focused brands have even a special “Cool biz line”, to address the huge demand that comes with the rising temperatures.
After the earthquake in 2011, and electricity shortage due to shut down nuclear reactors, the Japanese Ministry of Environment introduced an even more liberal campaign and launched the “Super Cool Biz” campaign. Additionally to having the air conditioners set to 28℃, to conserve energy, the government asks to switch off computers, which are not in use, plus to shift work hours to the morning and to allow employees to take longer summer vacation. Office attire rules were loosened too, by allowing clothes, which are still appropriate for the office yet cool enough to endure the summer heat. In some offices, polo shirts and sneakers are allowed while some companies even allow jeans and sandals if there are no meetings with customers.