2,700 people is the latest estimate of deaths in May and June from the ongoing UK heatwave, according to a team at Imperial College London, the Met Office and the London School of Hygiene and Tropical Medicine.
Heatwaves across the UK are becoming an increasing concern for many sectors and industries, and chief among them is the healthcare sector.
Ed Hawkins, Professor of Climate Science at the University of Reading, told the BBC this month that "Today's heat events are emerging earlier, intensifying faster and occurring across a much warmer background climate".
And these conditions are only likely to get worse with the effects of climate change.
When looking at the real-life impacts of this heat, it is healthcare buildings that will have the most dire consequences.
Healthcare buildings are filled with those who are most vulnerable to the impacts of this hot weather. When a body is already under pressure from an injury or illness, the added stress of heat can be fatal.
In addition, these are also the facilities that people already affected by heat-related conditions will move to. In June 2025, NHS England reported that there was a 198% rise in visits to its head exhaustion advice on its website.
Overheating can no longer be viewed as a seasonal inconvenience
So not only will the building temperatures be making patient status worse, there will also be an increased presence in these buildings at that time. This is a recipe for disaster.
The ageing estate of the NHS also means that when these facilities were built, there were not the same heat concerns as there are today. Meaning the design did not account for them.
Buildings are therefore designed to retain heat, which is one issue. In addition, they operate 24/7, and this comes with the added complication that the overnight cooling-off window is not as effective.
With reports seeing hospitals like Southampton General being brought “close to collapse”, it is clear something needs to be done about hospital design. Not only for exisitng estate, but for future design.
Dr Matthew Lee (Project Lead) is a resident doctor and the Sustainability Lead for Doctors' Association UK.
Lee said: “Hospitals and GP surgeries are not equipped to handle heat. They should be safe spaces for patients and staff, but currently pose imminent patient and staff safety risks.
“This is the latest baseline in extreme weather events. We need immediate climate adaptations in healthcare and an accelerated programme of decarbonisation and nature restoration to secure a liveable future.”
Lee also urged politicians of all parties to come together to make hospitals and GP surgeries safe.
How is heat impacting the patient in the hospital?
Building Better Healthcare spoke to Matt Maleki, Business Development Manager UK&I and IAQ Specialist at HVAC expert, Carrier.
Maleki emphasises that whilst the discomfort and inconveniences to the general public caused by this heat are a problem, the impact on hospitals “extends far beyond comfort”.
“Many NHS hospitals were designed for a cooler climate, at a time when prolonged heatwaves weren’t considered a significant design challenge,” he says.
He stresses that beyond the direct impacts on patients on wards, these high temperatures in these buildings can also “increase fatigue among clinical staff” and “compromise the performance of temperature-sensitive equipment that supports life-critical treatments and diagnostics”.
In real terms, this can be seen at hospitals like University Hospital Southampton, which declared a critical incident in late June due to the ongoing extreme heat.
“[The heat] is placing significant pressure on our services,” the Trust stated. “The high temperatures are affecting some of our systems and critical clinical services, including theatres and diagnostic imaging.”
The high temperatures are affecting some of our systems and critical clinical services, including theatres and diagnostic imaging
Rooms that require stable conditions include operating theatres, examination rooms, laboratories, pharmacies, blood banks and imaging suites.
“All [of these areas] depend on stable environmental conditions to protect patients, preserve medicines and samples and maintain the accuracy and reliability of specialist equipment.
What needs to change in hospital design to protect patients from heatwaves?
Maleki says that the answer isn’t just to install more cooling.
“From our experience supporting healthcare estates, they benefit most from a considered, whole-building approach that balances resilience with sustainability,” he explains.
In terms of adapting facilities to the new heat conditions, he points to build components like high-efficiency chillers, fan coil units, ventilation systems, and intelligent building controls. All of which should aim to provide “continuous optimisation” to maintain safe indoor conditions while minimising energy consumption and carbon emissions.
“I’m sure we’ll continue to experience warmer summers. Overheating can no longer be viewed as a seasonal inconvenience but as a long-term resilience challenge,” Maleki warns.
“Future healthcare developments and refurbishment programmes must incorporate climate adaptation into their design strategies, ensuring healthcare environments remain safe, reliable and fit for purpose during increasingly extreme weather conditions.”
