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legal alert: When is it too hot to work?

25 Jul 2019

Temperature gauges are rising across the UK – and your employees may be starting to feel the heat. Kerry Waters, associate at Watson Burton, looks at the implications for employers.

With parts of Europe seeing record temperatures this summer and heatwaves hitting much of the UK, many businesses may be struggling to keep their staff cool and comfortable.

It can be uncomfortable to work in a sweltering office – especially in older buildings without air conditioning – or in factories where heat generated by machinery already creates a warm working environment before weather plays its part.
But is there a legal maximum temperature limit for the workplace – after which point staff should be sent home?

The answer, perhaps surprisingly for some employers and employees, is no. There is no legal maximum and no guidance on a specific maximum temperature.

The Workplace (Health, Safety and Welfare) Regulations 1992 states that: “During working hours, the temperature in all workplaces inside buildings shall be reasonable.”

However, there are huge disparities over what could be deemed to be a ‘reasonable’ working temperature.

A bakery, steelworks or restaurant kitchen will naturally be warmer places to work than an office or shop. However, as long as appropriate controls are put in place, these environments can still be safe to work in.

Extreme temperatures in the workplace can have a negative impact on staff morale and can affect concentration levels and subsequently productivity and the ability to make decisions.

If a significant number of employees do complain of ‘thermal discomfort’ then an employer should undertake a risk assessment. ‘Thermal comfort’ describes a person’s state of mind in terms of whether they feel too hot or too cold, rather than a workplace temperature – it is influenced by both personal and environmental factors. Environmental factors include air temperature, radiant temperature (influenced by heat sources such as radiators and machinery), air velocity (the flow of air around a workplace) and humidity. Personal factors include clothing insulation and work rate/metabolic heat. A person’s physical characteristics can certainly have an impact on thermal comfort – and it’s worth noting that a study authored by Dr Boris Kingma from Maastricht University Medical Centre showed that most air conditioning units are based on the resting metabolic rate of a 40-year-old man, which runs up to 30 per cent faster than a woman’s. So, while men in an office may be perfectly comfortable, female employees may be reaching for a jumper…

We do note cases where Courts have found that implied terms apply to the effect that as an employer, they will provide and monitor, where reasonably practicable, a working environment which is suitable for the employee to carry out their contractual duties. This could cover temperature, but only extremes of heat would be likely to breach implied terms – and it can be difficult to identify where the boundaries lie.

As a responsible employer, you should of course take action to support your staff in keeping cool in the summer heat – air conditioning, ventilation, the provision of cold drinks etc should all be considered. If it’s possible for your staff to work from home – and if that practice is not at odds with your business requirements – then this could be a potential solution too.
So, although there is guidance on minimum temperature (HSE advises 16°C or 13°C if much of the work involves “rigorous physical effort”) there is no equivalent for maximum temperature.

A sensible approach, which takes into account staff wellbeing, is therefore all that can be recommended.

If you have concerns around other issues in your workplace environment and need legal guidance, contact Kerry Waters on 0345 901 2044 or at


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