The Workplace (Health, Safety and Welfare) Regulations 1992 suggest a minimum temperature in workrooms to be at least 16 degrees Celsius if you are working at a computer all day or 13 degrees Celsius if much of the work indoors involves severe physical effort. The Chartered Institution of Building Services Engineers (CIBSE) suggests a range from 20ºC to 24ºC for offices involving sedentary tasks.
The above regulations state that: ‘During working hours, the temperature in all workplaces inside buildings shall be reasonable.’
There is no definition of what is ‘reasonable’, and the application of the regulation depends on the nature of the workplace, eg a bakery, a cold store, an office, a warehouse.
HSE previously defined thermal comfort in the workplace as: 'An acceptable zone of thermal comfort for most people in the UK lies 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 more sedentary activities towards the higher end.'