Is there a maximum workplace temperature beyond which employees cannot be expected to work?
The Workplace (Health, Safety and Welfare) Regulations 1992 (SI 1992/3004) state that, during working hours, the temperature in all workplaces inside buildings should be reasonable. However, the Regulations do not provide a maximum workplace temperature.
What is reasonable will depend on the nature of the workplace and the activities undertaken.
The Health and Safety Executive (HSE) previously defined an acceptable zone of thermal comfort for most people in the UK as lying "roughly between 13°C (56°F) and 30°C (86°F), with acceptable temperatures for more strenuous work activities concentrated towards the bottom end of the range, and for more sedentary activities towards the higher end". The HSE's current guidance is that it is not possible to give a "meaningful" maximum temperature, as other factors such as radiant temperature, humidity and air velocity become more relevant in workplaces with high temperatures, such as glass works or foundries.
During a heatwave, employers should monitor their workplaces and ensure that temperatures do not become unreasonable. They should follow HSE guidance and implement measures to prevent employees becoming too hot, for example providing fans, relaxing formal dress codes and allowing employees to take extra breaks.