Maximum Working Temperature UK: What the Law Actually Says

It is October, and somewhere in a London office this week the annual thermostat argument has started. One person at the window desk is typing in a coat. Two desks away, someone else has a fan on because the radiator under their desk is doing the work of three. The office manager is fielding complaints from both and wondering, not for the first time, whether there is actually a rule about any of this.

There is, and it is shorter than people expect. The confusion comes from the gap between what the law says and what everyone assumes it says.

There is a minimum workplace temperature in UK guidance: 16°C for most indoor work, or 13°C where the work is strenuous. There is no legal maximum working temperature in the UK at all. The law, Regulation 7 of the Workplace (Health, Safety and Welfare) Regulations 1992, says only that the temperature in indoor workplaces must be reasonable during working hours. Everything else, the figures, the enforcement practice, the campaigns for a maximum, sits around that one word.

What the law actually says about workplace temperature

The governing rule is Regulation 7 of the Workplace (Health, Safety and Welfare) Regulations 1992. Its first paragraph reads, in full: "During working hours, the temperature in all workplaces inside buildings shall be reasonable." (Regulation 7, legislation.gov.uk). That is the whole legal test for temperature in an office or a shop.

The same regulation adds two practical duties that get forgotten. It requires that heating or cooling equipment must not release fumes likely to be injurious or offensive, and it requires that "a sufficient number of thermometers shall be provided" so people at work can check the temperature for themselves. If your staff are guessing how cold the room is, that second duty is not being met. A £10 thermometer on the wall settles more arguments than any policy document.

Note what Regulation 7 does not contain. No number. Not a minimum, not a maximum. The numbers everyone quotes come from somewhere else.

Where 16°C and 13°C come from

The figures live in the Approved Code of Practice that sits alongside the 1992 Regulations, known as L24. The Health and Safety Executive's own workplace temperature guidance puts it plainly: employers should provide a minimum working temperature in workrooms of at least 16°C, or 13°C where the work involves strenuous physical effort (Thermal comfort, HSE).

Guidance is not statute, and you will read plenty of articles making that point as if it means the figures do not matter. They matter. HSE explains that an Approved Code of Practice has "a special legal status": if you are prosecuted for a breach and it is proved you did not follow the relevant provisions of the code, you have to show you complied with the law in some other way (Legal status of HSE guidance and ACOPs, HSE). An office held at 14°C all January is a difficult position to defend.

So treat 16°C as the floor, not the target. Sedentary staff in still air are usually comfortable a few degrees above it, which is why most offices aim for the low twenties.

There is no maximum working temperature in UK law

HSE is direct about the other end of the scale: "There's no law for maximum working temperature, or when it's too hot to work." The reason is practical. A bakery, a foundry and a glassworks generate heat from the work itself, so no single figure can separate hot weather from a hot process. Parliament has been asked to fix this before. An Early Day Motion back in 2016, signed by 159 MPs, called for a statutory maximum of 30°C, or 27°C for strenuous work, and nothing came of it.

No maximum does not mean no duty. HSE's position is that employers must manage thermal comfort, which it defines as a combination of air temperature, radiant temperature, air movement, humidity, clothing and work rate. In a heatwave that means a risk assessment of heat stress, not a shrug. The TUC has called for an upper limit that would force employers to act once indoor temperatures reach 24°C, with 30°C (27°C for strenuous work) as the point where it argues enforcement should bite (Is there a maximum temperature in workplaces?, TUC). That call has been running for years and the pressure is not easing. Whether or not it becomes law, it tells you where enforcement expectations are drifting.

That may change. HSE is reviewing the Approved Code of Practice that sits behind the 1992 Regulations, and in a 2026 written answer to Parliament the government confirmed that HSE "has engaged with other departments across government in the development of the proposals for workplace temperature" and "will be consulting on the review of the ACOP". Nothing has changed in law yet. If a maximum does arrive, the workplaces that already control heat properly will have the least to do.

Too cold to work: the winter side gets ignored

Most of what is written on this subject is published in July. That is a shame, because the cold side is where the law actually has teeth, and it is the side London employers are thinking about right now.

HSE's warning applies in both directions: "People feeling uncomfortably hot or cold are more likely to behave unsafely." Anyone who has watched staff prop a fire door open for air in August, or wear gloves with poor grip in January because the packing area is freezing, has seen that sentence in practice. Cold hands make mistakes. Staff who are cold take shortcuts, huddle near heat sources, and leave doors closed that should be open.

For an office, the reasonable response to cold is not exotic. Heating that actually works and is serviced before October rather than after the first complaint. Draughts dealt with at doors and windows. Workstations moved away from cold glazing where the layout allows it. Local heaters where a corner of the building never warms up, provided they are PAT tested and not fan heaters aimed at a stack of paperwork. None of this is expensive. All of it is cheaper than the grievance, or the absence, that follows a winter of 14°C mornings.

What reasonable looks like in an office or shop

HSE lists engineering controls for temperature plainly: heating, air movement and air conditioning, alongside insulation and separating people from the source of heat or cold. Translating that into a normal London workplace:

• Summer. Blinds or film on sun-facing glass before the heat arrives, not during the complaint. Fans to move air, which helps even though they do not lower the temperature. Desks shifted out of direct sun. A relaxed dress code. Cold drinking water available. Strenuous tasks moved to the cooler part of the day.
• Winter. Heating serviced and balanced so one end of the floor is not roasting while the other freezes. Draught proofing. Local heating for genuinely cold spots. A thermometer people can see.
• All year. Someone responsible for checking conditions and logging complaints, so you can show a pattern of reasonable response rather than a pattern of being told.

None of this is exotic. That is rather the point. The employers who get into difficulty over temperature are rarely the ones who could not afford to act. They are the ones who never wrote down what they did.

A seasonal checklist for a London workplace

Here is the practical version, the one I wish more office managers had in front of them before the season turns.

Before winter	Before summer
Service the heating and test it under load on a cold morning	Service cooling plant and clean filters before the first warm week
Check thermostats read true against a known thermometer	Fit or check blinds and solar film on sun-facing glass
Draught proof doors and windows; check door closers work	Confirm fans work and there are enough of them for the floor
Identify cold spots and agree local heating for them	Agree a dress code and break policy for hot spells in writing
Put thermometers where staff can see them	Check cold drinking water is available on every floor
Log temperature complaints and what you did about each one	Add heat to the risk assessment and review it after any heatwave

Run both columns and you have an answer ready the day someone asks whether the building is legal. More useful, you have a building where nobody asks.

When fixed air conditioning is the sensible answer

Fans and heaters are coping strategies. They move air or warm a corner, and in a mild week that is enough. But a building that swelters every July and freezes every January is telling you something about its fabric and its services, and no quantity of desk fans fixes that.

This is where fixed air conditioning earns its keep, because modern systems are air-to-air heat pumps: the same unit cools in summer and heats in winter, usually more cheaply than the electric heaters staff smuggle in. We have written separately about how air conditioning doubles as heating and about what air conditioning actually costs to run, because the running cost question is usually the first one a finance director asks. Spaces with their own heat loads, like server rooms, follow different rules again, and our guide to server room temperature covers those.

The pattern we see in London offices is consistent. A business puts up with portable units and fan heaters for three or four years, spends a surprising sum on electricity doing it badly, then fixes it properly once. Once installed, the system has to be looked after, because a neglected unit in July is worse than no unit at all, which is what planned air conditioning maintenance exists for.

Frequently asked questions

What is the legal minimum workplace temperature in the UK?

The regulations themselves set no figure. The HSE Approved Code of Practice gives 16°C for most indoor work and 13°C where the work involves strenuous physical effort. Those figures carry special legal status: if you are prosecuted and did not follow them, you must show you complied with the law another way. In practice, treat 16°C as the floor.

Is there a legal maximum working temperature in the UK?

No. HSE states plainly that there is no law for a maximum working temperature or for when it is too hot to work. Instead, employers must keep temperatures reasonable and manage heat as a risk, which in hot weather means assessing thermal comfort and heat stress and taking practical steps to control it.

Can employees refuse to work because it is too hot or too cold?

Only in narrow circumstances. Section 44 of the Employment Rights Act 1996 protects an employee who leaves or refuses to return to a workplace where they reasonably believe there is "serious and imminent danger" (Section 44, Employment Rights Act 1996). Discomfort is not danger. A genuinely dangerous temperature, heat stress risk in a kitchen during a heatwave, say, can be. The sensible route for staff is to raise it internally first, and the sensible route for employers is to have done something before it comes to that.

What temperature is too hot to work in an office?

There is no legal cut-off, so the honest answer is: when people cannot work comfortably and safely, the employer should be acting. The TUC argues employers should be forced to act at 24°C and that 30°C should be the hard limit. HSE's measure is thermal comfort, which weighs humidity, air movement, clothing and work rate alongside the number on the thermometer.

Do employers have to provide thermometers?

Yes. Regulation 7 requires a sufficient number of thermometers so that people at work can determine the temperature in their workplace. It is one of the cheapest legal duties you will ever meet, and one of the most commonly ignored.

Does workplace temperature law cover shops and customer-facing premises?

Yes. The 1992 Regulations apply to workplaces inside buildings generally, which includes shops, salons, cafés and showrooms, not just offices. Customer comfort is a commercial question on top of that, but the legal duty runs to the staff who work there all day.

Getting the temperature right, properly

Most temperature problems in London workplaces are not legal problems at all. They are buildings being asked to do something their heating or cooling cannot manage, with staff absorbing the difference. The law asks for reasonable. Your staff ask for comfortable. A system that heats in January and cools in July answers both, and it answers them every day rather than in the week after someone complains.

If your office or shop is fighting the seasons with fans and fan heaters, talk to us about commercial air conditioning in London. We will tell you honestly whether fixed plant is worth it for your building, including the occasions when it is not.

About the author: Ali Elm runs Be Cool Refrigeration & Air Conditioning, a family-run London firm that has been installing, servicing and repairing commercial refrigeration and air conditioning since 2004. His F-Gas certified team has delivered more than 2,000 projects across London and the South East.

Last updated: 7 October 2026