As the UK experiences warmer summers and more frequent discussions about workplace comfort, energy use and resilience, there may be value in revisiting a simple but powerful idea from Japan: Cool Biz.
Launched by Japan’s Ministry of the Environment in 2005, Cool Biz encouraged offices to reduce excessive air conditioning by setting indoor cooling to around 28°C and relaxing formal dress codes so employees could work comfortably without jackets and ties.
It was a cultural shift as much as an energy-saving campaign: a recognition that professional standards do not have to be defined by clothing designed for cooler climates.
The early results were significant. Japan’s Ministry of the Environment estimated that the first Cool Biz campaign reduced carbon dioxide emissions by approximately 460,000 tonnes, while also helping organisations manage energy demand during the hottest months.
This approach could help reduce cooling costs, cut emissions and improve wellbeing
Martin Fahey Head of Sustainability for Mitsubishi Electric
What is ‘reasonable’?
For the UK, the conversation is different but increasingly relevant.
We currently have guidance on minimum indoor workplace temperatures, but there is no fixed legal maximum temperature for workplaces.
Instead, employers are required to provide a “reasonable” working temperature and assess heat as a health and safety risk. That leaves room for practical, risk-based decisions — but it also raises an important question: should we be more proactive in adapting how we work during hot weather?
A UK version of Cool Biz would not simply mean turning up thermostats. It could mean smarter seasonal workplace policies: breathable professional clothing, flexible working patterns, better shading, improved ventilation, access to cool drinking water, sensible use of fans and air conditioning, and clearer guidance for managers on thermal comfort and heat stress.
Less air conditioning
The sustainability opportunity is obvious. Cooling demand can be expensive, carbon-intensive and highly variable during peak periods.
Reducing unnecessary air conditioning, while still protecting people’s health and comfort, supports lower energy costs, lower emissions and better climate resilience.
Perhaps the bigger lesson from Japan is cultural. Cool Biz worked because it challenged assumptions about what “business appropriate” looks like in summer.
In the UK, as we talk more about maximum indoor working temperatures, maybe we also need to talk about maximum common sense: designing workplaces, dress codes and expectations around the climate we now have — not the climate we used to have.
Could a UK Cool Biz approach help reduce cooling costs, cut emissions and improve workplace wellbeing? I think it is a conversation worth having.
Martin Fahey is Head of Sustainability for Mitsubishi Electric
