Underfloor cooling, how the green alternative to air conditioning chosen by Paris for the Olympic village works

The solution chosen by the French capital does not convince all delegations.And (among those who can afford it) the race for portable air conditioners begins

Exactly one month before the inauguration ceremony, there is a bad feeling at the Paris 2024 Olympics.While half the world is grappling with yet another record heat wave - from 47 degrees in Phoenix, USA, to 49 in Delhi, India - athletes are also starting to worry about the temperatures in which they might be forced to compete.The bone of contention is the promise made by the municipality of Paris to make this year's Olympics the greenest ever.An objective that the French capital aims to achieve through a rather complex strategy:use existing sports facilities, prefer river transport (the Seine) to road transport and use sustainable building materials, such as wood.However, there is a point in this plan that worries many athletes: the absence of air conditioning in the accommodation of the Olympic village.

How underfloor cooling works

According to a reports by Basis, an English association for sustainable sport, the Paris 2024 Olympics risk being the hottest ever.Climate change is obviously to blame, with Europe warming at almost double the rate of the rest of the world.To reduce the ecological footprint of the accommodation that will host Olympic athletes from all over the world, the mayor of Paris Anne Hidalgo has focused on a more sustainable alternative to traditional air conditioners.This is geothermal underfloor cooling, a system that exploits the temperature difference between the subsoil and the surface to regulate the internal temperature of a building.In fact, it is a dense network of pipes installed under the floor, within which chilled (or hot, depending on needs) water circulates.This system exploits the physical principle of radiation, according to which a hot body always transfers heat to a cold body.In this way, the cooling system allows the heat present in the room to be absorbed when the air temperature exceeds the surface temperature of the floor.

Advantages and limitations

The great advantage of this mechanism is that it allows you to use a single system for both summer air conditioning and winter heating.While on the surface the temperature is influenced by atmospheric agents and the change of seasons, at depth it is relatively stable and constant throughout the year.Furthermore, compared to traditional systems, underfloor cooling allows you to lower energy consumption and avoid the classic temperature changes caused by air conditioners.Alongside the advantages, however, there are also two major obstacles.The first is strictly economic, given that the installation of a system of this type has much higher initial costs than the alternatives on the market.The second limit concerns the effectiveness of the mechanism itself, certainly useful for cooling a home but not enough to withstand the impact of strong heat waves.

The race for portable air conditioners

And it is precisely this last point that worries many athletes in view of the Paris Olympics.According to the organizers, the cooling system of the accommodation in the Olympic village guarantees a lowering of temperatures by at least six degrees compared to the outside.Too little for some delegations, with the United States athletes having already made it known that they are working to bring some portable air conditioners with them.This is an option that the organizers of Paris 2024 advise against, but do not prohibit.The Washington Post interviewed twenty national delegations to ask how they were organizing themselves.The answer?Eight countries have confirmed that they will equip their athletes with portable air conditioners.These are Australia, Canada, Denmark, Germany, Greece, Italy, Norway and the United Kingdom.

African countries are falling behind

The cost of portable air conditioning systems will fall entirely on individual delegations.This means that poorer nations, who cannot afford extra expenses, will be forced to have their athletes sleep in warmer rooms than their competitors.“We don't have enough money,” explained Donald Rukare, president of the Uganda Olympic Committee, to Washington Post.Meanwhile, the organizers of the Olympic Games themselves are intervening in the debate to try to restore calm.The athletes, assured the director of the Paris Olympic village, "will be able to rest properly".Mayor Anne Hidalgo said she was sorry for the choice of some countries not to give up air conditioning, adding that she had "a lot of respect for the comfort of the athletes" but specifying that she had "the survival of all humanity" even more at heart.

On the cover:A building in the Paris 2024 Olympic village (EPA/Mohammed Badra)