How to keep subways and trains cool in an ever hotter world

To its credit, TfL has made many efforts over the years to try to deal with the problem of hot tunnels, including Attaching cooling panels to the tunnel walls. The panels, which circulate water to remove heat from the air, were deployed in a trial in 2022, although they are not currently in use. Paul says such a system could be expensive.

Hassan Hamida, from the University of Birmingham, says Paul’s water-cooling technology is a “good idea”, although it remains to be seen how much heat it can really remove from a crowded tube station full of people in real life.

Some railways are simply pushing the limits of our ability to calm things down, Hamida says. He gives the example of high-speed trains traveling at 400 kilometers per hour, for example. They push air out of their way at high speeds, which means compressing the air surrounding the HVAC equipment on the roofs of those trains. It can decrease significantly. “And then you can’t suck the air into the HVAC system,” he says. Ultimately, this may cause the air conditioning unit to malfunction. Hamida adds: “I have been contacted by colleagues from China who want to find a solution to this problem.”

However, more and more train operators are adopting air conditioning systems as standard. For example, London’s relatively new Elizabeth Line features air conditioning. A spokesman for Skoda Transport, which recently introduced air conditioning, said Metro trains in the capital of Bulgaria“In general, every vehicle we produce now has air conditioning,” he says. Sharon Hedges, senior engagement manager at Transport Focus, an industry watchdog, adds: “As people think about buying new caravans, these are the things that should be top of mind right now.”

Heatwaves are one thing in Britain. What about the Egyptian desert? German technology company Siemens is supplying Egypt with a new set of high-speed trains that can travel at speeds of up to 230 kilometers per hour. The company’s Velaro trains are used in many places across Europe, but for Egypt, Siemens has put them into practice. Last summer, the company took one of the trains to a testing facility in Austria and exposed it to unpleasant conditions, including temperatures of up to 60 degrees Celsius and high winds. “We achieved an indoor temperature of 26 degrees even under the hottest outdoor conditions,” says Björn Buchholz, Head of HVAC and Door Systems.