Launched in 2005 to reduce energy consumption during Japan’s hot summers, Tokyo’s Cool Biz campaign has evolved to meet the challenges of a warming climate. From encouraging lighter workplace attire to promoting year-round changes in how people work, live, and dress, the initiative reflects a broader approach to balancing comfort, health, and energy conservation. In this interview, the Tokyo Metropolitan Government explains how the campaign has adapted to increasingly extreme heat, the lessons learned over two decades, and how its experience could inspire cities in Japan and around the world.

I seem to understand that your Tokyo Cool Biz campaign started in 2005. Why was this campaign so relevant?

Cool Biz is an initiative launched in 2005 by Tokyo Governor Koike Yuriko, when she was the Minister of the Environment, to beat the summer heat with season-appropriate attire while saving energy. We believe it was significant in encouraging the widespread adoption of everyday energy-saving practices by wearing clothes suited to room temperatures instead of using excessive air conditioning during the summer. By encouraging government agencies and businesses to take the lead, the initiative also served as a catalyst for reconsidering workplace dress codes during summer and fostering a culture that values both comfort and energy conservation.

The climate conditions are, though, now different. And the 2026 campaign has changed. Can you explain how it changed?

Given the increasingly frequent extreme heat and the current energy situation, the Tokyo Metropolitan Government (TMG) believes it is important to protect the lives and health of Tokyo residents while promoting energy conservation in sustainable ways. From FY 2026 [April 2026-March 2027], we expanded the previous Cool Biz concept, which focused primarily on clothing, into a new lifestyle initiative encompassing how people work and live. Under the name Tokyo Cool Biz, it is now a year-round initiative. Specifically, we encourage measures to "cool down" three environments—in how we work, live, and dress. These measures include early-morning shifts, teleworking, the use of tools such as heat checkers, and comfortable clothing suitable for the temperature and work responsibilities.

What did you learn in 20+ years of this campaign? How is your experience potentially useful for other municipalities in Japan and in the rest of the world?

TMG recognizes that flexible dress practices, such as foregoing ties and jackets in response to temperature and job requirements, have become widely accepted and firmly established in workplaces. Building on this experience, we believe that expanding such initiatives throughout society requires the administration to lead by example while presenting practical actions that residents and businesses can readily incorporate into their daily lives. While climate conditions, cultural norms, and workplace practices differ by city, we hope that TMG's efforts to balance health, comfort, and energy conservation through a range of options tailored to local circumstances will serve as a useful model for cities in Japan and around the world.

What are the conditions to make the campaign work? How can it also be applied to women?

To establish Cool Biz as a lasting practice, government agencies, companies, and others need to lead by example by creating environments in which employees can make flexible choices about their attire and work styles based on temperature and job requirements. In addition, efforts should extend beyond clothing to include heat mitigation measures and work styles that can be adopted without undue strain. Tokyo Cool Biz does not require a uniform dress code, regardless of gender. Instead, it encourages individuals to choose comfortable attire and work styles suited to their job responsibilities and workplace environment. We believe it is important not only to provide a range of options but also to foster workplace cultures in which different choices are understood and respected.

Are you planning to change this policy in the future?

TMG aims to establish Tokyo Cool Biz not as a temporary campaign, but as a year-round lifestyle. We will continue to lead by example while expanding awareness among residents and businesses and encouraging municipalities, companies, and other organizations to incorporate these practices into their daily operations. Considering factors such as climate conditions and the energy situation, we will also continue to support behavioral changes that balance health, comfort, and energy conservation.

Are you collaborating with other governments to implement similar measures?

TMG is encouraging the wards and other municipalities within Tokyo, companies, and organizations to promote Tokyo Cool Biz through posters, stickers, and other outreach materials. In addition, by leading by example and actively communicating its own efforts, TMG seeks to encourage wider implementation, allowing organizations to incorporate these measures in ways that suit their workplace environments and operational needs.

Are you working on other climate adaptation measures?

Besides the Tokyo Cool Biz initiative, TMG is pursuing a multifaceted approach to climate adaptation, including measures to protect residents from extreme heat and address the urban heat island effect. Going forward, bureaus across TMG will continue to collaborate closely to advance climate adaptation efforts that help safeguard the lives, health, and property of Tokyo residents.