“HOW hot does it have to get in the office before we can legally go home?”

It’s a complaint often heard during heatwaves like the one currently gripping Britain.

But thermometer watching employees shouldn’t down tools yet, because the Health and Safety Executive’s guidance leaves enough grey areas to make it a tricky question to answer.

HSE previously defined thermal comfort in the workplace as: 'An acceptable zone of thermal comfort roughly between 13°C (56°F) and 30°C (86°F).

The law does not state a minimum temperature, but the temperature in workrooms should normally be at least: 16°C, or 13°C if much of the work is physical, say the HSE.

While regulation seven of the Workplace (Health, Safety and Welfare) Regulations 1992 lay down particular requirements for most aspects of the working environment, the application of the regulation depends on the nature of the workplace – working as a baker being quite different from working in cold storage, for example.

At the upper end of the scale though, things seem even less well defined.

Where the temperature in a workroom would otherwise be uncomfortably high, the HSE say that ‘all reasonable steps should be taken to achieve a reasonably comfortable temperature’.

Insulating hot plants or pipes, shading windows and siting workstations away from radiant heat are all suggested.

If that doesn’t work, HSE suggest suitable protective clothing and scheduled breaks.

‘Typical examples of suitable protective clothing would be ice vests, or air/water fed suits’ say the HSE – probably without officers workers in mind.

Judging by the HSE’s guidance, the best an average office worker can hope for is to adopt and all-for-one attitude and complain en-masse.

HSE guidance states that your employer made need to consider carrying out a ‘thermal comfort risk assessment- if:-

More than 10 per cent of people in an air conditioned office complain of being too hot or cold.

The figure rises to 15 per cent in air conditioned offices and 20 per cent in retail business, warehouse, factories or other indoor environments without air conditioning.

However – this being Britain, after all – it’ll most likely be raining again by the time you’ve mobilised enough support.

If you’re thinking of organising your own rebellion, find out more at hse.gov.uk/temperature/faq.htm