This 123-year-old air-con system has lessons for managing today's sweltering heat

As climate change roasts cities around the world, air conditioning can be the difference between life and death for vulnerable people – but it comes with heavy costs. The long history of air conditioning in public spaces shows what is at stake.

There is a giant six-blade fan in the brick wall before me. The fan, painted a glossy red and set neatly into a circular hole in the wall, must weigh multiple tonnes. But when I put my hand on one of its blades, it turns easily – without so much as a squeak, as though it were installed yesterday. The slightest breeze wafts down from the contraption as it slowly decelerates, returning to a halt.

"Amazing isn't it," marvels Alan Luney, senior estates officer at Belfast's Royal Victoria Hospital in Northern Ireland. "After all these years, that you can spin that. I mean, there's not a noise out of it."

I'm standing inside a 123-year-old air conditioning system made of brick and iron. Installed in 1903 to cool now-demolished original wards, this system made the Royal Victoria Hospital one of the first mechanically air-conditioned public buildings in the world.  

The fan once drew air across a jungle-like arrangement of coconut fibre ropes that were regularly moistened with cool water in the summer. That air then flowed along a 150m-long (490ft) corridor with an upwards-sloping floor. Openings in the corridor's walls allowed temperature- and humidity-controlled air to reach hospital wards above, through hidden ducts.

The aim? To improve patient recovery times and, ultimately, save lives.

With global temperatures rising and heatwaves becoming ever more extreme, the role that air conditioning plays in public health has become increasingly important. The need is clear. High temperatures, besides sometimes being deadly, may also make people more aggressive, or adversely affect their decision-making. Heatwaves can even reduce the efficacy of certain medicines. Public access to cool spaces is being promoted by many cities worldwide, with some even installing purpose-built, air-conditioned climate shelters.

But to really understand the significance of air conditioning as a health-preserving intervention, you should turn to its historical origins.

Although the Royal Victoria Hospital's giant fan and coconut fibre cooling system has since been superseded by more modern and more hygienic technology, it remains a testament to the life-saving power of air conditioning. Access to air-conditioned buildings drastically reduces the risk of heat-related mortality and one study found that each year, air conditioning averts around 195,000 deaths globally among people older than 65.

"Cooling is the number one most important approach to reduce the health risks of heat – and often what's required is air conditioning, or active cooling," says David Eisenman, a physician and health researcher at the University of California Los Angeles' Fielding School of Public Health.

In hospitals, air conditioning can play a vital role, reducing the risk of patients dying by up to 40% in extreme heatwaves. Hospital cooling equipment failures are treated as "critical incidents" during hot weather.

Florence Nightingale, nursing pioneer and social reformer, promoted various hygienic interventions, including the freshening of air in 19th Century hospitals. Most doctors and nurses achieved this at the time simply by opening the windows.

The architects of the Royal Victoria Hospital's wards in 1903 sought to create a healthy environment in a city where infant mortality was high and pollution from factories and mills was diabolical. The water-soaked coconut ropes not only cooled incoming air, they captured soot and dust, too.

"It was about creating what we would call a hygienic environment," says Nigel Keery, head of estates operations at the Belfast Health and Social Care Trust. "That involved not having to open windows where coal dust and soot was coming in."

The resulting system – parts of which were made by the same company that manufactured ventilation fans for the Titanic – was "very effective", he adds. Doctors working at the hospital reported outdoor temperatures of 26C (80F) in the shade during the summer after the facility opened to patients. But the air conditioning system kept the wards inside to a far more comfortable 18C.

In the 1860s, an American inventor proposed an ice-based air-cooling system for a hospital, though this did not include humidity control.

Hospital designers and medical professionals of the early 20th Century had clearly recognised the benefits of indoor air control as health-boosting. Gradually, people began to promote such interventions in other places.

Today, in the Indian city of Jodhpur, there is a public cooling station – a cabin-like building that, for the past two years, has offered relief to people during periods of extreme heat.

Residents of Jodhpur must sometimes endure outdoor temperatures of around 50C (122F). To combat this, the cabin's walls are partly made of fibrous panels made from a dried grass called khus that is misted with water. It's a traditional way of cooling indoor spaces – and very much like the moistened coconut ropes in the Royal Victoria Hospital.

Electric fans powered by solar energy pull air across the damp khus curtains at the Jodhpur cooling station, lowering the temperature inside by as much as 12C (22F).

"It has been actively used since it was inaugurated in 2024," says Prima Madan, director of cooling and climate resilience at the Natural Resources Defense Council, a non-profit advocacy group that was involved in the cooling station's design. The facility is frequently used by people who spend significant time outdoors including women, delivery drivers and street vendors.

This concept of providing publicly accessible cool spaces fitted with air conditioners is catching on. Spain recently announced a national programme to establish a network of climate shelters – air-conditioned spaces that will generally also provide drinkable water and places to sit.

"If you know that five minutes from your house or your workplace, or on the way from the market, you start to feel too hot but you can reach a climate shelter within 100m (328ft) – I think that's essential," says Ana Terra Amorim-Maia, a climate adaptation scientist at the Basque Centre for Climate Change in Spain, who has studied climate shelters in the country.

Cities that have previously not had to worry much about high temperatures are also now turning to public cooling in order to help citizens cope. Officials in the city of London have launched an interactive map identifying libraries, museums, concert venues and other locations that are reliably cool. Churches, which are often naturally cool during hot weather due to their stone construction, are also listed.

Some people are seeking their own answers to the question, "Where can I cool down?"

One London resident, Tianyin Pan, recently made an online map, highlighting businesses that have, or are likely to have, air conditioning. He created Stay Cool, an online directory of restaurants, pubs and cafés compiled using publicly available data on, for example, building energy performance. Pan cautions that the website is not 100% accurate but says he is working to update and improve it.

Public access to cool spaces is only going to become more sought-after as global temperatures rise, says Niamh O Regan, senior researcher at the Social Market Foundation, a think tank based in the UK. "I think people haven't maybe adjusted to the fact that this will become much more normal."

To see just how disastrous extreme heat can be for human health and the difference air conditioning can make, the devastating heatwave that struck Europe in 2003 offers a stark example. It killed more than 20,000 people – some of them in the intensive care unit at Fondation Hôpital Saint-Joseph in Paris, where intensive care doctor Benoît Misset worked at the time.

"I remember very well the heatwave of 2003," says Misset, who is now retired. "Each day was very difficult."

He recalls specific cases. A baker who collapsed in front of his bread oven as temperatures rose. A worker on a construction site. A young postman, whose car lacked air conditioning. The temperature inside the vehicle must have reached 50C (122F) or more, estimates Misset. "He got out of the car and [collapsed] in the street. He was transferred to the hospital – and he died."

Misset and his colleagues were also struggling in the sweltering conditions. Back then, their intensive care unit didn't have air conditioning. Some patients were arriving severely dehydrated but the worst cases were in a kind of heat-induced coma. Desperate to offer patients relief, Misset's staff attempted to cool down water bottles in fridges before placing them on patients' bodies. "The refrigerators were not able to refresh enough litres of water," he says.

In 2006, Misset and colleagues published a study gathering together data on more than 340 heatstroke patients admitted to 80 different intensive care units around France during the 2003 heatwave. While other factors influencing patient survival cannot be completely ruled out, the study noted a striking correlation: "Patients managed without air conditioning had a 76% increased risk of death."

Despite his experience, and the study's results, Misset remains somewhat cautious about air conditioning because of its environmental impact, along with the cost of installing and running it.

Air conditioning already accounts for 7% of the world's electricity use, and releases 2.7% of the world's carbon dioxide (CO2) emissions from fossil fuels and industry. Some research indicates that the significant energy demands of air conditioning systems will intensify global warming, and release more climate-warming CO2 than the United States by 2050. Then there are the refrigerants used inside air conditioners. Some of these gases are thousands of times more potent for global-warming than CO2.

There are other problems. If electricity generated with fossil fuels is used to power air conditioners, that could also increase air pollution-related deaths, counterbalancing the health benefits of air conditioning, according to a study from Greece.

However, alternatives such as passive cooling – achieved by shading buildings and windows, painting roofs white to reflect heat or adding insulation to block heat from getting inside – may not be enough in many places, says Catherine Noakes, an environmental engineer at the University of Leeds in the UK.

"We've gone past being able to do it all passively, particularly in cities," she says. "When it's really, really hot outside, it's very challenging."

Many hospitals, for example, still struggle without air conditioning – more than 120 years after Belfast's Royal Victoria Hospital got its pioneering system. Noakes points out that hospital staff today often turn to electric fans, which can be effective for cooling people down at a low cost so long as temperatures don't exceed roughly 40C (104F). Fans also risk spreading airborne pathogens around a ward, says Noakes.

There is huge demand from hospitals around the world for air conditioning systems at the moment, says Jose La Loggia, EMEA group president at Trane Technologies, which has many clients in the healthcare and pharmaceutical sectors.

The French Government recently allocated €100m (£86m/$114m) in emergency funding to buy 30,000 air conditioning units for healthcare facilities while the country struggled with a brutal heatwave at the end of June. And a May 2026 report by the independent Climate Change Committee, which advises the UK government, has warned that £144m ($191m) per year will need to be spent on cooling healthcare facilities in England and Wales over the coming decades.

Today, even Belfast's Royal Victoria Hospital is not 100% air conditioned. It's "too expensive" says Keery.

He says that interest in the hospital's original, pioneering air conditioning system has only grown in recent years, though. "We kept it going as engineers," he says. "It was in a forgotten corner."

Preserved almost in its entirety, but no longer connected to functioning wards, it serves as a reminder of why air con matters so much for public health. "Amazing, isn't it?" says Luney.

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