What Temperature Should a Commercial Workplace Be? UK Law Explained

BBC News is reporting today on how UK buildings are struggling to cope with this summer’s heatwave. Across the North West and beyond, we’re hearing the same thing from businesses getting in touch with us. Staff are uncomfortable, productivity is suffering, and employers are asking the same question: at what temperature are we legally required to act?

There is no legal maximum workplace temperature

This is the part that catches most employers off guard. Under the Workplace (Health, Safety and Welfare) Regulations 1992, indoor workplaces must be maintained at a “reasonable” temperature during working hours. The regulations set a minimum – normally 16°C for office-based work, or 13°C for physically demanding roles – but they do not set a maximum.

The HSE has explained why. In some industries, high temperatures are an inherent part of the work itself. A bakery or a foundry operates in heat that would be unacceptable in an office, and a single fixed ceiling would make no practical sense across both environments.

The figure that circulates most often is 30°C, but this isn’t law. It’s a threshold campaigned for by the TUC, which has long argued that employers should be required to act once temperatures exceed 24°C for sedentary work and that 30°C should constitute an absolute ceiling. That proposal has not been adopted in legislation.

What has changed recently is the direction of travel. In May 2026, the Climate Change Committee recommended that the government commit to introducing a national maximum workplace temperature. Following a parliamentary question in June, the government confirmed that the HSE is now reviewing its Approved Code of Practice for the 1992 Regulations, with a public consultation expected. Nothing has changed in law yet, but the review is underway.

So, what are employers legally required to do?

The absence of a numerical ceiling doesn’t mean employers are off the hook. The Health and Safety at Work etc. Act 1974 places duty on employers to protect the health, safety and welfare of their staff from all foreseeable risks. And during summers like we’ve had in recent years, heat is very much a foreseeable risk.

In practical terms, that means:

• Employers must maintain a reasonable temperature in the workplace
• Carry out a risk assessment where heat poses a risk to workers
• Provide thermometers so staff can check temperature levels
• Consult with workers on steps to address thermal comfort
• Take all reasonable steps to improve conditions where temperatures are a problem.

It’s also worth noting that some groups are more vulnerable to heat than others – including pregnant workers, older employees, and those with underlying health conditions. Identifying and supporting those individuals should form part of any heat risk assessment.

Why “reasonable” becomes harder to defend as temperatures climb

The word “reasonable” carries a lot of weight in the legislation, and what it means in practice shifts with the conditions. Opening windows and putting out a few fans might be a reasonable response during a standard warm week. During an amber or red UKHSA heat-health alert – with overnight temperatures staying above 20°C and daytime highs pushing 35°C or beyond – that bar is considerably higher.

Businesses without mechanical cooling are already finding that temporary measures can’t keep pace with conditions like these. Staff complaints, higher absenteeism and reduced output are the early warning signs. The longer those conditions persist without a meaningful response, the more exposed an employer becomes – whether that’s through an HSE complaint, a tribunal claim, or an insurance dispute over workplace welfare.

The law may not give you a number to work to, but the consequences of falling short are very real.

Here’s what businesses can actually do about it

There are short-term steps worth taking while you assess your options. These include:

• Using blinds and external shading to limit solar gain
• Improving cross-ventilation
• Introducing portable fans
• Providing cool drinking water
• Offering flexible or remote working where roles allow

For some buildings in some conditions, that’s enough. For many commercial spaces (particularly modern glazed offices, south-facing units, high-occupancy premises, or buildings with heat-generating equipment) it isn’t. 

UK building stock was largely designed to retain heat, not shed it. Add in the increasing humidity of UK summers and a baseline temperature that keeps creeping up, and mechanical cooling shifts from a nice-to-have to a practical necessity.

If you’re already at that point, it’s worth knowing that demand for commercial AC installation is at its peak right now and lead times are extending. Businesses that move quickly may be able to get systems within weeks. Those who wait until next summer will find themselves in the same position again, only further back in the queue. 

Our guide to how long commercial air conditioning installation takes covers what to expect by building type.

How Atmostherm can help

With over 40 years’ experience designing and installing commercial HVAC systems across the North West, we can assess your building, recommend the right solution, and give you a clear picture of costs and timelines before any work begins – whether you need a single unit for a small office or a full multi-zone system for a larger site.

Get in touch to arrange a no-obligation air conditioning survey, or take a look at our case studies to see how we’ve helped businesses like yours.

FAQs

Is there a legal maximum workplace temperature in the UK?

No. The Workplace (Health, Safety and Welfare) Regulations 1992 require workplaces to be kept at a reasonable temperature but set no numerical upper limit. The HSE is currently reviewing its Approved Code of Practice following government commitment to update guidance on extreme heat, but nothing has changed in law yet.

Can employees refuse to work if it’s too hot?

Not automatically – there’s no temperature at which employees have an automatic legal right to stop work. That said, where an employer has clearly failed to take reasonable steps to address the heat, employees may have grounds for a formal grievance or, in serious cases, a constructive dismissal claim. The HSE can also investigate complaints and issue improvement notices.

What’s the most effective way to cool a commercial workplace?

The most effective way is air conditioning. Short-term measures (fans, shading, ventilation, flexible working) can take the edge off but have clear limits. A commercial air conditioning system that’s correctly sized for your building will maintain consistent conditions regardless of what’s happening outside, protecting both staff welfare and day-to-day productivity.