There is no legal maximum temperature for UK workplaces, and no legal minimum either. What the law does require is a reasonable temperature indoors. Guidance suggests at least 16°C for most indoor work, or 13°C where the work involves rigorous physical effort. Employers must also assess temperature as a risk and act on what they find. This guide explains what those rules mean for an office, shop, workshop or any other indoor workplace, and what to do when the temperature stops being reasonable.
TL;DR
- UK law asks for a "reasonable" indoor temperature. It sets no fixed figure for how hot a workplace can be.
- The guidance minimum is 16°C, or 13°C where much of the work is rigorous physical effort. It is guidance, not a legal limit.
- Employers must assess temperature risks and put controls in place, including temporary or seasonal ones.
- If you are too hot or too cold, raise it with your employer first. Acas and your union rep can help if that fails.
- Cooling and heating are controls you can fit permanently. A well-sized system is often cheaper than repeated stop-gap fixes.
Table of Contents
- What UK law actually says about workplace temperature
- Minimum workplace temperature: 16°C and 13°C
- Is there a maximum workplace temperature in the UK?
- What employers must do about heat and cold
- Practical controls that work
- A simple temperature risk assessment
- What to do if your workplace is too hot or too cold
- Our perspective: when a workplace needs more than a fan
- Getting a workplace sorted with Frost Air Conditioning
- Quick reference: what applies where
- FAQ
- Sources
What UK law actually says about workplace temperature
The main rule sits in the Workplace (Health, Safety and Welfare) Regulations 1992. According to the HSE's page on the law, these regulations require employers to provide a reasonable indoor temperature, and what counts as reasonable depends on the work activity and the environmental conditions.
That wording matters. A warehouse picker, a hairdresser and an accountant at a desk do very different work. The law does not give them the same number. It asks the employer to judge what is reasonable for each setting, and to be able to show how they reached that judgement.
Two other pieces of law sit alongside it:
- Management of Health and Safety at Work Regulations. Employers must assess the risks to workers and put controls in place. HSE says temperature is one of the risks to assess, indoors or outdoors.
- Construction (Design and Management) Regulations. These require reasonable temperatures in indoor areas of construction sites. Outdoor sites need protection from adverse weather, and rest facilities must be kept at an appropriate temperature.
The Workplace Regulations are supported by an Approved Code of Practice, published by HSE as L24, Workplace health, safety and welfare. That is where the familiar 16°C and 13°C figures come from.
Minimum workplace temperature: 16°C and 13°C
The GOV.UK guidance on workplace temperatures says there is no legal minimum temperature, but suggests a minimum of 16°C, or 13°C if the work involves physical effort. HSE words it slightly differently: the Approved Code of Practice suggests that the minimum for working indoors should normally be at least those figures.
In practice:
| Type of work | Guidance minimum |
|---|---|
| Office, retail counter, reception, most sedentary or light work | 16°C |
| Work involving rigorous physical effort, such as some workshop or warehouse tasks | 13°C |
Three points trip people up:
- It is guidance, not a hard limit. A reading of 15°C is not automatically a breach. But an employer who ignores it with no assessment will struggle to say the temperature is reasonable.
- It applies to the working area. A heated office with a freezing entrance lobby is judged differently from an unheated unit where people sit all day.
- Some work needs colder rooms. Food storage, for example, has its own requirements. Reasonable depends on the activity.
Is there a maximum workplace temperature in the UK?
No. HSE states there is no maximum temperature in its guidance on the law, and Acas confirms there is no legal maximum working temperature, saying the HSE's advice is that temperatures inside buildings should be reasonable.
This surprises many people. Other countries set a ceiling beyond which work must stop or change. The UK does not. A 35°C workroom is not illegal on that basis alone. But it is very hard to call it reasonable, and an employer who does nothing is exposed under the risk assessment duty.
So the question is never "has the thermometer hit a number?" It is "has the employer assessed the heat, and are the controls proportionate?"
What employers must do about heat and cold
The core duty is to assess and act. HSE spells out that employers must assess the risks to workers and put controls in place to protect them. For temperature, that looks like this:
- Decide what is reasonable for your workplace. Consider the type of work, how physical it is, the clothing staff wear, and how many people share the space.
- Assess the risk. HSE offers a heat stress checklist for situations where workers may be affected by heat. Use it when people report discomfort or you have equipment, glazing or processes that add heat.
- Put controls in place. HSE says these can include temporary or seasonal measures.
- Consult your people. HSE says you should consult workers or their representatives on the best ways to cope with high or low temperatures.
- Review. A south-facing office that is fine in March can be unbearable in July.
Acas adds that vulnerable workers deserve extra thought. People with health conditions or disabilities may be affected more by hot weather, and employers should discuss what would reduce or remove the risk. Its suggestions include fans, portable air-cooling units, or more frequent or longer breaks.
Why temperature is a health issue, not just comfort
The Approved Code of Practice links temperature to productivity, morale and physical health. At the extremes, heat can lead to illnesses such as heat stroke, and cold can lead to cold stress. That is why HSE treats it as a risk to be managed rather than a matter of preference.
Practical controls that work
Controls fall into a rough order of effectiveness. Start with the source, then the environment, then the people.
Reduce the heat or cold at source
- Move heat-producing kit, such as printers, servers and ovens, away from where people sit, or into a ventilated room.
- Add blinds or solar film to glazing that takes direct sun.
- Fix draughts, broken seals and failed heating zones before winter.
Control the environment
This is where fixed equipment comes in. Fans move air but do not lower the temperature, and in a closed, very hot room they can only go so far. Portable units are a stop-gap: they need a window or duct for the hot exhaust, take floor space and are noisy.
A permanent split or multi-split system cools (and on most modern models heats) the room properly, with controlled thermostats and filtered air. Our guide to the role of air conditioning in UK offices covers when a workplace has crossed the line from "fans will do" to "we need a system". If you are planning a layout, designing office air conditioning by area explains how sizing works for spaces under 200 m².
If you also need winter warmth, many systems run in reverse. Air conditioning can heat a UK building, with some caveats about outside temperature and insulation.
Adjust how people work
- Allow flexible hours so staff can start early on the hottest days.
- Relax dress codes in heat; provide warm layers or heaters in cold spells.
- Provide cold drinking water and more frequent breaks.
- Rotate people out of the hottest tasks.
Temperature thresholds affect trades and materials too. Outdoor finishing work, for example, has its own cut-offs: this note on UPVC spraying in winter shows how a 10°C limit changes whether a job can go ahead. The same thinking applies to risk assessments: write down the temperature at which you change the plan.
A simple temperature risk assessment
You do not need specialist software. A sensible record for a small business includes:
- Where and when: which rooms, which times of year, which tasks.
- Readings: a few thermometer readings at working height during the hottest and coldest parts of the day.
- Who is affected: including anyone more vulnerable, and anyone near heat sources or sun-facing windows.
- Complaints: what staff have told you, and when.
- Controls: what you have put in place, who is responsible and when you will review it.
Keep the record. If an employee or inspector asks how you decided the temperature was reasonable, that file is your answer.
What to do if your workplace is too hot or too cold
If you are an employee, start with a conversation. GOV.UK advises that if you find the temperature uncomfortable, you should talk to your employer to discuss the issue and possible solutions.
A sensible sequence:
- Raise it with your manager, ideally in writing so there is a record. Give specifics: the room, the times, how it affects your work or health.
- Suggest a fix. Moving a desk, opening blinds, adjusting hours or fitting a fan or heater can be quick wins.
- Involve a safety or union representative if there is one. HSE says employers should consult workers or their representatives.
- Speak to Acas for free guidance if the issue is not resolved.
- If you have a health condition, tell your employer and your GP or occupational health adviser. Heat and cold affect people differently.
Can I refuse to work in 40 degree heat?
There is no figure in UK law at which you may walk out, so there is no simple yes. An employer has to assess and control heat risk, and you should not be expected to carry on in conditions that are clearly unsafe. If you believe you are in danger, stop and speak to your employer, safety rep or union straight away, and get advice from Acas before taking any step that could affect your pay or job. Do not simply leave without raising it first.
Our perspective: when a workplace needs more than a fan
We install air conditioning across Exeter, Devon, Cornwall and the wider South West, and the pattern is familiar. A business puts up with a hot back office or a cold shop floor for a couple of summers or winters. Then it buys three portable units, then a fourth, and then someone finally asks for a survey.
Our view is that the legal framework makes the decision for you more often than people realise. There is no magic number, but "reasonable" is hard to defend when staff are repeatedly reporting discomfort and your only control is a desk fan. A properly specified system gives you a documented, adjustable control, which is exactly what a risk assessment wants to see.
A few things we would tell any employer:
- Size the system to the room, not the budget. Undersized units run flat out and still miss the target temperature.
- Think year-round. A heat pump air conditioner that heats in winter helps with the 16°C guidance as well as summer cooling.
- Use certified engineers. Our engineers are F-Gas certified and REFCOM registered, which matters because refrigerant handling is regulated. We do not use subcontractors.
- Plan maintenance from day one. Dirty filters and low refrigerant quietly bring back the problem you paid to solve. See whether a maintenance contract suits your business.
- Keep the paperwork. Record the installation, the set-points and your assessment together.
Most of our domestic and commercial installations are completed within one to two days, and same-day or next-day installs are available when a heatwave or cold snap forces the issue.
— James
Getting a workplace sorted with Frost Air Conditioning
If you manage a shop, office or other commercial premises in the South West, our shop fitting and commercial service covers survey, design, installation and handover, using systems from Samsung, Mitsubishi, Toshiba and Daikin. Surveys are free, and 0% finance is available.
Working from home, or running a small business from a converted outbuilding? Our domestic installation service handles single-room systems, and our service and maintenance plans include annual contracts and emergency breakdown response. Prices depend on the survey, so we do not publish a fixed figure.
Quick reference: what applies where
| Question | Short answer |
|---|---|
| Is there a legal minimum? | No, but guidance suggests 16°C, or 13°C for rigorous physical work |
| Is there a legal maximum? | No fixed figure; the temperature must be reasonable |
| What law applies? | Workplace (Health, Safety and Welfare) Regulations 1992, plus risk assessment duties |
| Who decides what is reasonable? | The employer, based on an assessment of the work and conditions |
| What if staff are uncomfortable? | Talk to the employer, then a rep or Acas |
| What counts as a control? | Anything that reduces the risk, including temporary or seasonal measures |
FAQ
What is the legal minimum temperature at work in the UK?
There is no legal minimum. The Approved Code of Practice suggests indoor workplaces should normally be at least 16°C, or 13°C where much of the work involves rigorous physical effort. Employers still need to keep the temperature reasonable and assess the risk if it is not.
Is there a maximum legal working temperature?
No. UK law gives no upper limit, and both HSE and Acas say so. The employer must still provide a reasonable temperature and assess heat risks, so a very hot workplace with no controls can still put the employer in the wrong.
What should I do if my office is too hot or cold?
Talk to your employer and describe the problem and when it happens. Suggest practical fixes, and involve a safety representative or union rep if you have one. If it is not resolved, Acas offers free workplace advice.
What must employers do about temperature?
They must assess temperature as a workplace risk and put controls in place to protect workers. That can include seasonal or temporary controls such as fans, breaks or flexible hours, and permanent ones such as heating or air conditioning. They should also consult staff on what would work.
Does air conditioning make a workplace compliant?
Not automatically, because the law asks for a reasonable temperature and a managed risk rather than a particular piece of equipment. A correctly sized system, kept maintained and set sensibly, is one of the most reliable ways of showing that you have controlled the risk. Keep your assessment on file alongside it.
Sources
- Workplace temperatures, GOV.UK
- Temperature in the workplace: What the law says, HSE
- Workplace health, safety and welfare (L24), HSE
- Acas tips to help employers manage hot weather at work