It is no suprise that after the recent record temperatures that the top HR question asked in June was:
Is there a maximum workplace temperature beyond which employees cannot be expected to work?
The answer according to Xperthr.co.uk is
“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.
The Health and Safety Executive 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”. What is reasonable will depend on the nature of the workplace and the activities undertaken.”
Check out http://www.personneltoday.com/hr/top-10-hr-questions-june-2017-maximum-workplace-temperature/ for the full list of questions.