Cool Biz: How a Nudge Changed Japan's Office Dress Code

Japan changed what an entire country wears to work without passing a law. In April 2005 the environment minister read out an anonymous complaint at a press conference: an employee had gone to a government energy-saving meeting without a tie, been called ignorant of common sense, and been demoted. Unless the state changes first, the writer said, we can't change even if we want to. Six weeks later the Prime Minister and his cabinet were working without ties or jackets. Twenty years on, the man in a tie in a Tokyo office in July is the exception. If you have ever tried to introduce a new rule in a Japanese subsidiary and watched it die quietly, Cool Biz is worth taking apart.

What happened in the summer of 2005

The sequence matters. On 25 April the Ministry of the Environment picked the name "COOL BIZ" from about 3,000 public submissions and announced it on the 27th. On the 28th, minister Yuriko Koike defined it: no tie, no jacket, from early June to the end of September, with air conditioning set to 28°C. At the same briefing she explained the cabinet's own arrangement. Ministers had agreed among themselves to work in light dress as a rule, with exceptions for receiving foreign guests, award ceremonies and similar formal occasions. The Prime Minister, she said, had not ordered anyone to wear anything; dress for the occasion, and the general sense was that everyone should dress cool. A line about staying within the bounds of social common sense was included from day one.

It started on 1 June. An Associated Press report filed just before the start quotes Junichiro Koizumi: if the ministers are wearing a tie, their subordinates would feel uneasy about not wearing it, so the ministers should not wear a tie. He himself appeared in a newspaper ad in a half-sleeve shirt with no tie. The same report notes that the idea had been tried before, under Prime Minister Ohira in 1979 and Prime Minister Hata in 1994, and had failed both times.

So 2005 was the third attempt at the same thing.

How much actually changed?

Almost everyone knew about it in the first summer. It took two years for behavior to catch up. A Cabinet Office survey in June and July 2007 (face-to-face, 1,766 valid responses) included a comparison with July 2005. Awareness of Cool Biz rose from 76.6% to 91.2%. People who said they practiced it rose from 16.4% to 46.6%. Threefold in two years. The Cabinet Office notes that the 2005 question was worded differently, and the answer option changed too (from "working on it" to "practicing it"), so I read this as an order of magnitude rather than a precise figure.

The environment ministry's own numbers come from online panels. At the end of September 2005, 95.8% of about 1,200 respondents knew about the campaign, but only 32.7% of the 562 who answered the question said their office air conditioning was set higher than in previous years. By September 2006 that was 43.2%.

On the company side, a Teikoku Databank survey put adoption at 37.1% of companies in 2005, cited in an April 2006 report by Dai-ichi Life Research Institute. The same report put the 2005 Cool Biz market at about 92 billion yen, citing a Nihon Research Soken estimate. AP had a smaller, more vivid number: men's shirt sales at Mitsukoshi's Nihonbashi store were up 17% in May 2005 on the year before.

Nearly everyone knew, but it took two years for practice to go from 16% to 47%

Cabinet Office special opinion survey, nationwide, age 20+, face-to-face. July 2005 (1,626 valid responses) and June 2007 (1,766). The Cabinet Office notes the question wording differed between the two

Know about Cool Biz　spread in the first summer

• July 2005
  76.6%
• June 2007
  91.2%

Practice it　no tie, no jacket

• July 2005
  16.4%
• June 2007
  46.6%

Two years separate knowing from doing. Role models, a name, written exceptions and clients filled them.

One caveat on the CO2 figures. The ministry announced a reduction of about 460,000 tonnes for 2005 and about 1.14 million tonnes for 2006. That looks like more than a doubling, but in 2006 the ministry revised the energy saving assumed per degree of cooling from 16.33 kWh a year to 30.24 kWh, which alone multiplied the estimate by about 1.85. Both years' figures are extrapolated from surveys, not measured, and the press release says so. Treat them carefully as environmental results. As evidence that clothing changed, they're fine.

Why did 1979 fail and 2005 succeed?

Because 2005 solved the problem of being the only one. What you wear to work is a coordination problem. As long as your clients, competitors and boss wear ties, the first person to take one off looks careless. That is exactly what the anonymous letter was saying. Koike reached for a Japanese proverb at the briefing, "if everyone crosses on red, nobody is afraid," and then half took it back. But it is the core of the design. Broken down, it looks like this.

Name it first. A public contest, 3,000 entries, one winner, then a logo. A name gives people an excuse. In a client's meeting room you can say "it's Cool Biz" and never have to explain personally why you aren't wearing a tie. The same outfit without a name is an individual lapse. With a name it is compliance with a public rule.

Put the role model ahead of the rule. The cabinet agreement bound civil servants, roughly 250,000 national bureaucrats. What reached the private sector was the photograph of the Prime Minister and his ministers without ties, and Koizumi's sentence about subordinates. He said out loud what everyone knew: the boss dressing formally is itself pressure on everyone below him.

Write the rule as numbers. June 1 to September 30. 28°C. The 28 wasn't arbitrary. The government's own PR site explains it as the upper bound of the indoor temperature range set by the Building Sanitation Act ordinance and the office hygiene rules under the Industrial Safety and Health Act (17°C to 28°C at the time, 18°C to 28°C since April 2022). With a date and a temperature, no company's general affairs department had to hold a meeting about whether it applied to them. They copied it.

Write the exceptions first. Foreign guests, ceremonies, common sense, all stated on day one. A rule without written exceptions dies the day the first exception shows up.

Push from outside. Department stores and shirt makers moved first, because there was money in it. In 2011, after the Great East Japan Earthquake, "Super Cool Biz" extended the period to May 1 through October 31, and the Japan Department Stores Association's 86 member companies and 242 stores raised their thermostats from mid-May. Once the market is on the side of the campaign, individuals no longer have to choose.

Repeat every year. The ministry issued a notice every spring and published numbers every autumn. A campaign lasts twenty years because it has a fixed place on the calendar.

Where foreign companies' new rules die in Japan

Reverse those steps and you get the failures I see most often in foreign-owned subsidiaries.

The top doesn't do it. Headquarters tells the Japan team to write in English, and keeps sending mail in its own language. The country manager who announces no overtime is on chat at nine in the evening. Koizumi's sentence works in reverse too: what the top won't do, the bottom can't.

No name, no numbers. "Be more flexible from now on" is an instruction Japanese staff cannot execute. From when, to what degree, with which situations excluded? None of it is specified. As I wrote in Set the rules in the first ninety days, or don't bother, a rule becomes a rule when it is written in a form you could pin to a wall.

Clients left out of the calculation. You abolish honorifics internally and flatten the titles, and the next morning your salesperson walks into a client where the bucho and the kacho are very much still there. Your rule stops at your own front door. Outside it is another ba, another social field. Why global matrix structures break in Japan describes the structure: people follow the rules of the field they belong to, and a new rule that doesn't cover that field doesn't bind.

Announced once. The HQ policy is imported, a memo goes out, and the rollout is declared done. Don't run a startup-stage entity like head office made the point that institutions have to grow locally, and growing locally means someone restating them every year.

And a sense of scale. Cool Biz went from 16% to 47% practice in two years, with the Prime Minister in front, the department stores behind and the whole country watching. If a new rule in your forty-person Japan subsidiary hasn't taken after six months, that is normal. Concluding that Japanese employees are conservative can wait.

Since 2021, no official period at all

The last move is the most interesting. The ministry's April 2022 notice says that, as in the previous year, it will not set a uniform nationwide Cool Biz period; regions should decide based on local temperatures and working styles. After pushing for more than fifteen years, the government withdrew the calendar. It was no longer needed. Taking off a tie no longer required a name to explain it.

The best ending for a rule is that the behavior survives the rule's exit. That is my test for whether a new rule in a company has worked: take the memo down, and see whether people keep doing it.

Two things I haven't resolved. First, 28°C is still argued about. The ministry's wording is a guideline for room temperature; many offices run it as the thermostat setting, and the two differ by several degrees. The central number of a twenty-year campaign is still being misread. Second, the CO2 savings were survey extrapolations from start to finish, and I couldn't find a measured figure. So this piece can say Cool Biz changed what Japan wears. It can't say how much electricity it saved.

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