The Paris Olympics is going underground to find a way to keep athletes cool at the 2024 Games without air conditioners.

Organisers are planning to use a water-cooling system under the Athletes Village — much like the one that has helped the Louvre Museum cope with the sweltering heat that broke records last year — to keep temperatures in check for the Olympians and Paralympians who stay there.

The decision is part of the organising committee’s goal to cut the carbon footprint of the Paris Games by half and stage the most sustainable Olympics to date by installing a special technology to use natural sources to keep everyone cool even during a potential heat wave.

“I want the Paris Games to be exemplary from an environmental point of view,” said Paris Mayor Anne Hidalgo, who has resolved to tackle climate change with an ambitious action plan that aims to drastically reduce greenhouse gas emissions and make the City of Lights carbon neutral by 2050.

Compared to a conventional project, the carbon impact will be reduced by 45 per cent for the Athletes Village during the construction phase and over the entire Olympic cycle, she said.

For two months between July and September 2024, the Athletes Village north of Paris will host 15,600 athletes and sports officials during the Olympics and 9,000 athletes and their supporting teams during the Paralympics. After the games, the 50-hectare (125-acre) site next to the River Seine in the popular district of Seine-Saint-Denis will become a zero-carbon, eco-friendly residential and commercial neighborhood with 6,000 new inhabitants — the first ones moving in as soon as 2025.

In anticipation of hot weather, organisers have been studying heatwaves block by block in the Athletes Village. They have simulated conditions in the parts of the accommodation most exposed to the sun and have tested the effectiveness of the cooling system with an objective to keep the indoor temperature between 23 and 26 degrees Celsius (73 and 79 degrees Fahrenheit).

The geothermal energy system will ensure that the temperature in the athlete apartments in the Seine-Saint-Denis suburb does not rise above 26 degrees Celsius (79 degrees Fahrenheit) at night, including during a potential a heat wave, said Laurent Michaud, the director of the Olympic and Paralympic Villages.

He said organisers have conducted tests in rooms that are located on the highest floors of the residences and are facing south and exposed to direct sun on two sides. They also considered directions of winds in the region and the water temperature in the Seine. They have worked closely with France’s national weather agency to develop temperature forecasts.

“Despite outdoor temperatures reaching 41 degrees Celsius (106 degrees Fahrenheit), we had temperatures at 28 degrees (82 degrees Fahrenheit) in most of these rooms,” Michaud told The Associated Press, detailing the results of a heatwave simulation. “In other rooms, we clearly had lower temperatures.”

In addition to the underfloor cooling, the insulation built into the buildings will enable residents to keep the cold obtained during the night throughout the day, Michaud said. To keep the coolness inside, the athletes will have to follow some basic rules, he added, including making sure the window blinds are shut during the day.