1. How the Kyoto Protocol Led Japan to Call for Light Summer Clothes
On February 16, 2005, the Kyoto Protocol took effect. This was an international agreement to reduce greenhouse gases that cause global warming. Japan was obligated to cut emissions by 6% compared to 1990 levels. [1] This 6% target had to be met on average between 2008 and 2012. Reaching this goal could not be done just by changing summer clothing. [1]
However, there were things that could be changed in hot offices: the air-conditioning settings and the clothes people wore. In the summer of 2005, the government ran a campaign to set air conditioning to 28°C (82°F) and encouraged a "no necktie, no jacket" style. [1] Who started this call to action?
2. How the Prime Minister's Advice to the Environment Minister Started the Campaign
In 2005, it is said that Prime Minister Junichiro Koizumi advised Environment Minister Yuriko Koike to create a catchphrase for saving energy by wearing light summer clothes. [1] However, this story is not confirmed in Ministry of the Environment documents. We cannot say for certain that the Prime Minister proposed the idea, so it is best to say that "advice is said to have been given." [1]
What is clear is what happened next. To turn the idea of "working coolly in light clothes" into a short phrase everyone could understand, the Ministry of the Environment asked the public for names. [1]
3. How "COOL BIZ" Was Chosen from About 3,000 Public Entries
From April 1 to 15, 2005, the Ministry of the Environment asked the public for names for a new summer business style. Anyone could submit as many entries as they liked. The stated purpose was to further raise awareness of global warming by widely soliciting names from the public. [1] About 3,000 entries were collected. An expert review committee selected "COOL BIZ," and it was announced on April 27, 2005. The person who submitted the name was Hideaki Tagata from Tachikawa City, Tokyo. [1]
This name aimed to promote a light summer style where people could work comfortably, efficiently, and stylishly, even with air conditioning set around 28°C (82°F). The Ministry positioned this campaign as part of the "Team Minus 6%" movement to prevent global warming. [1]
Instead of saying "please endure the heat," the campaign encouraged people to "work stylishly." The name reflects this attitude. But can people really work at 28°C (82°F)?
4. Why the Ministry Said Going Without a Tie and Jacket Feels 2 Degrees Cooler
The Ministry of the Environment showed research results stating that "without a necktie and jacket, the perceived temperature drops by 2 degrees" as the reason people could work comfortably at 28°C (82°F). [1]
The logic is simple. Imagine the refreshing feeling of taking off a thick jacket on a hot summer day. By wearing lighter clothes, the heat felt by the body can be kept about the same even if the air conditioning is set higher. [1]
However, the name of the study and its specific conditions are not listed in the Ministry’s announcement. It is not a guarantee that it "will always drop by 2 degrees." It is more accurate to read it as "explained based on research results." Individual perceptions of heat also vary. [1]
5. How the First-Year Results and the 460,000-Ton Estimate Were Reported
In October of that year, the Ministry announced that 95.8% of people surveyed had heard of Cool Biz. [1] In December, they looked back on the campaign as having "caused a huge boom." Cool Biz was also selected as one of the top ten new words and buzzwords of 2005. [1] Companies also took action. Daiei, a supermarket chain, set the temperature to about 28°C (82°F) in all stores and offices for the summer, serving customers and working in Cool Biz style. [1]
The Ministry estimated the CO2 reduction for the first year at about 460,000 tons. This is equivalent to the CO₂ emissions produced by about 1 million households in one month. [1]
This figure is not a direct measurement but an estimate based on surveys. Out of 1,200 people surveyed nationwide via the internet, 562 were employed. The calculation used the percentage of these workers (32.7%) who answered that "the air conditioning temperature at their workplace was set higher than usual." [1] How did this movement continue after that?
6. How Cool Biz Changed from a Fixed Period to Personal Judgment
The standard implementation period was from June 1 to September 30. In 2011, due to the power situation after the earthquake, government offices extended it from May 1 to October 31. Since 2021, the Ministry of the Environment has not set a fixed period, leaving it to individual judgment. [1] In 2025, it has been 20 years since the concept was proposed. [1]
Documents from the National Institute for Environmental Studies describe Cool Biz as a word that has become established as a synonym for "appropriate room temperature management and light clothing suitable for that temperature." [1] This shows how the meaning of the word has broadened since the name was decided in the spring of 2005. [1]
7. How to Find Out What Cool Biz Was Like in 2005
Why not ask your family or teachers about what the summer of 2005 was like when Cool Biz started? What impressions did they have of the no-necktie style? Did the air conditioning in their workplaces change? Answers will likely differ from person to person.
Another option is to search the Ministry of the Environment website for terms like "Cool Biz 2005" to find press releases from that year. The name solicitation, logo decision, and results announcements are all published. You can read the original text to see what survey was used to produce the estimate of 460,000 tons. [1]