TfL to Retrofit Bus Cabs With Air Conditioning by 2027 Following Driver Heat Complaints

Transport for London (TfL) has committed to fitting air conditioning to every bus driver’s cab by the end of May 2027, after industrial action by drivers who reported working in cabs that regularly climbed past 40°C. The agreement, reached with the union Unite, will also see cabs fitted with UV protective film to reduce the risk of skin cancer.

I’ve spent nearly four decades around problems like this one, and the part that stays with me isn’t the air conditioning. It’s the reminder that heat is a hazard we can foresee, assess and control, whether or not there is a number written into law. This story reaches well beyond London’s depots.

Key Takeaways

• TfL will retrofit air conditioning to all bus driver cabs by the end of May 2027, after drivers reported cab temperatures above 40°C.
• Great Britain has no legal maximum working temperature. The legal test is a “reasonable” indoor temperature under the Workplace (Health, Safety and Welfare) Regulations 1992.
• Employers still carry a firm duty to assess and control heat under the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations 1999.
• The HSE is reviewing the Approved Code of Practice behind the workplace temperature rules, with a public consultation expected.
• The practical answer doesn’t wait on the review: treat heat as a foreseeable risk and act before someone is harmed.

What Has TfL Actually Agreed To?

In short, cooler cabs for drivers, on a deadline. Every driver’s cab that doesn’t meet TfL’s current ventilation and cooling standard will be retrofitted by the end of May 2027, and cabs will gain UV protective film as well. Newer buses already meet a tougher standard; the older vehicles were bought when extreme heat in London was rarer, so they are the ones being brought up to scratch.

It is worth being precise about what this is and isn’t. This is a negotiated commitment between an employer and a union, not an enforcement action by the regulator. Unite raised it, drivers backed it with industrial action, and TfL agreed to fix it. Unite’s general secretary Sharon Graham called the conditions drivers faced this summer “appalling”, and TfL’s director of buses acknowledged how hard the recent weather has been on staff. That route, where workers raise a concern and the employer responds, is how the system is meant to work when heat starts making people ill.

Is There a Legal Maximum Working Temperature in the UK?

No, and there never has been. For anyone coming to this cold, that surprises a lot of people. The Workplace (Health, Safety and Welfare) Regulations 1992 require indoor workplaces to be kept at a temperature that is “reasonable” during working hours. That single word is the whole legal test at the top end. The supporting Approved Code of Practice sets a floor of 16°C, or 13°C where the work involves rigorous physical effort, but it attaches no ceiling.

The HSE’s long-standing position is that a single meaningful upper limit cannot sensibly be fixed, because in plenty of workplaces the heat comes from the work itself rather than the weather. Think of bakeries, commercial kitchens and foundries, where high temperatures are a daily feature of the job. A figure that made sense for an office would be unworkable on a hot production line.

If There’s No Limit, What Does the Law Actually Require?

Quite a lot, as it turns out, and the absence of a maximum is not a loophole. Under Section 2 of the Health and Safety at Work etc. Act 1974, every employer has a general duty to ensure, so far as is reasonably practicable, the health, safety and welfare of employees. The Management of Health and Safety at Work Regulations 1999 then require a suitable and sufficient assessment of the risks people face, and heat is one of those risks like any other.

So the real test isn’t “have we breached a temperature figure?” It is “have we assessed the risk from heat and taken reasonably practicable steps to control it?” A driver passing out at the wheel, or a warehouse worker collapsing with heat exhaustion, is a foreseeable harm. Foreseeable harms are precisely what the law expects you to manage.

What Should Safety Professionals Do Now?

Here is where I would focus. Vehicle cabs are a good prompt, because mobile and lone workers often slip through heat planning that was written with a fixed building in mind. A cab in slow traffic on a still July afternoon is a small, glazed, poorly ventilated box, and the person inside is operating heavy machinery in public. That combination deserves a proper assessment, not an assumption that the driver can simply open a window.

The wider picture is moving the same way. The HSE is reviewing the Approved Code of Practice for the 1992 Regulations, including the temperature provisions, and a public consultation is expected. Unions including the TUC and Unison continue to press for a legal maximum of 30°C indoors, or 27°C for strenuous work, and the Climate Change Committee recommended in 2026 that government set maximum temperature rules for work. None of that is settled law yet, so I would caution against telling your board a limit is “coming”. We covered the state of that review in an earlier edition, HSE to Review Workplace Heat Rules as Pressure for a Legal Limit Grows. The direction of travel is clear, and the organisations that assess heat properly now will not be scrambling if the guidance tightens.

A few practical steps I would prioritise:

• Put heat in your risk assessments explicitly and record your significant findings, as the 1999 Regulations expect.
• Look hardest at your most exposed people: drivers, outdoor workers, kitchen and plant-room staff, and anyone working in PPE.
• Agree trigger temperatures and the actions that follow before a heatwave, not during one.
• Design the heat out where you can, through cooling, shading, ventilation and scheduling, before relying on water and breaks alone.
• Listen to the people doing the work. TfL’s drivers flagged this long before it reached a formal agreement.

Frequently Asked Questions

Is It Ever Legally Too Hot to Work in the UK?

Not in the sense of an automatic right to down tools. There is no legal maximum working temperature, so there is no fixed figure at which work must stop. Your employer does, however, have a duty to assess the risk from heat and take reasonably practicable steps to keep you safe.

What Temperature Is Too Hot for a Work Vehicle or Cab?

There is no set figure in law. TfL drivers reported cabs above 40°C, which is plainly a level at which heat illness becomes likely. The right approach is to assess the specific cab, the work and the conditions, rather than wait for a single national number.

Does an Employer Have to Provide Air Conditioning?

Not specifically. The law requires a reasonable temperature and control of the risk, not one named solution. Air conditioning is one reasonably practicable option among several, alongside ventilation, shading, sensible scheduling and rest.

Is the HSE Introducing a Maximum Working Temperature?

Not at present. The HSE is reviewing the Approved Code of Practice behind the workplace temperature rules and a consultation is expected, but no legal maximum has been set. We will cover any change in this series as it happens.

That’s this week’s story, from the depot floor to the risk assessment. For more of this analysis, sign up for the Astutis Quarterly Newsletter for our pick of the developments shaping workplace health and safety, or catch up on more editions of This Week in Health and Safety on the Astutis Hub. And if you’d like to talk through what any of this means for your organisation, get in touch.