The Green Party is preparing to push for a legal maximum workplace temperature in Britain, arguing that existing health and safety rules are no longer enough for a country facing more frequent and more intense heatwaves.
Hannah Spencer, the Green MP for Gorton & Denton, is expected to introduce a private member’s bill that would create an independent body to recommend safe maximum temperatures at work and advise on how those limits should be enforced.
The proposal comes during another period of exceptional heat, with office attendance already falling sharply as workers struggle with high temperatures, school disruption and transport pressure. Figures shared with the Times by Remit Consulting, which tracks office access-card swipes across ten UK cities, showed average occupancy dropping from 45.2% in the week ending 19 June to 37.5% in the week ending 26 June, as temperatures climbed towards 38C.
What the law says now
At the moment, there is no legal maximum workplace temperature in Britain. Employers are required to keep workplace temperatures “reasonable” and to manage risks to workers’ health and safety, but the law does not set a fixed upper limit. The Health and Safety Executive treats heat as a workplace hazard like any other, meaning employers have legal duties to assess and manage the risk, but the accompanying guidance states clearly that there is no maximum temperature specified for workplaces, only a minimum of 16C, or 13C for strenuous work.
That is the gap the Greens want to close. Trade unions have argued for years that the current approach leaves too much room for employers to do too little until conditions become dangerous. The Trades Union Congress has called for a maximum indoor workplace temperature of 30C, falling to 27C for physically demanding work. The Climate Change Committee, the government’s independent adviser, has also backed maximum working temperature targets, arguing they would improve worker safety and push employers to invest in cooling.
Why this is becoming a workplace issue
The argument is no longer just about comfort. Extreme heat affects concentration, raises the risk of illness and can make some jobs significantly more dangerous, especially for people working outdoors, in vehicles, in kitchens, in warehouses, on building sites or in protective equipment.
The Health and Safety Executive already expects employers to treat heat as a hazard. That can mean providing shade, ventilation, cooling, drinking water, altered hours, longer breaks or changes to the work itself. But without a clear legal maximum, the decision often rests on individual employers deciding what is “reasonable”. Campaigners say that is too vague for the kind of summers Britain is now experiencing.
The UK Health Security Agency has been issuing heat-health alerts across England during the current heatwave period, with several regions under warning focused on the risks to health and public services. Fire services have also been dealing with serious wildfires, with major incidents declared in parts of Wales and Derbyshire.
The current heat has already prompted debate over whether schools should close during the most extreme days, and has become a recurring flashpoint in the wider climate argument, with commentators including GB News’s Tom Harwood facing sharp criticism for downplaying the link between fossil fuel extraction and the emissions driving these conditions.
The business pushback
Industry groups are already warning that a legal maximum could be difficult to apply evenly across the economy. An office with air conditioning, a restaurant kitchen, a care home, a delivery depot and a construction site all face very different kinds of heat risk. A simple number on a thermometer may not capture humidity, direct sunlight, machinery, protective clothing or the physical intensity of the work.
That is why some business groups are pushing for guidance rather than hard legal limits. Matthew Percival, of the Confederation of British Industry, told the Times that a “commonsense approach” was needed, particularly for workers in roles where protective clothing or site conditions limit flexibility.
Construction firms have raised a separate concern. If outdoor work has to stop during the hottest hours, employers may also need changes to permitted working hours, noise rules and delivery restrictions so that work can move earlier in the morning or later in the evening. Rico Wojtulewicz of the National Federation of Builders called a legal maximum “not practicable” without those wider changes.
Hospitality leaders have also warned against rigid rules. Kate Nicholls, chief executive of UKHospitality, said “arbitrary targets can get in the way of productive discussions with teams about comfort and management of workplace matters”, arguing employers need room to manage comfort and safety directly with their own staff.
How other countries deal with heat at work
Britain would not be the first European country to regulate workplace heat more directly. Spain strengthened its rules after severe heatwaves in 2023, requiring employers to adapt working practices during official heat alerts, including changing hours or suspending some outdoor tasks. Belgium uses a more technical heat-stress system based on the wet bulb globe temperature index, which accounts for humidity, radiant heat and air movement rather than relying only on air temperature. In parts of Italy, outdoor work is temporarily banned during the hottest part of the day when extreme heat warnings are in place.
That international context matters because the most common argument against a British legal limit is that heat is too complicated to regulate with one blanket figure. Spencer’s proposal appears to recognise that problem by calling for an independent body to recommend safe limits and enforcement methods, rather than simply writing one number into law and leaving every industry to work around it.
The politics of heat
The government has so far resisted calls for a legal maximum workplace temperature, saying last week that it had no plans to introduce one, though the Health and Safety Executive is preparing a consultation on updated workplace temperature guidance that falls short of what unions, climate advisers and the Greens are calling for.
The bill is unlikely to become law quickly, especially as a private member’s bill without government backing. Its political importance may be in forcing ministers to answer a practical question that will become harder to avoid every summer: how hot is too hot to work?
That question is now part of a wider argument about how Britain adapts to a warming climate. Previous climate debates have often focused on national targets, energy policy and net zero commitments, including recent interventions from figures like John Major, who has argued that scrapping net zero amounts to telling future generations “tough luck”, and Tony Blair, who has called for the policy to be reconsidered as part of a broader political recalibration. Workplace heat brings the issue into offices, schools, care homes, buses, kitchens and building sites.
For employers, the challenge is practical. For workers, it is immediate. As Britain gets hotter, the legal fiction that “reasonable” temperature is enough may not survive many more summers.
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