At the arrivals terminal at Roland Garros airport on Réunion island, visitors are greeted by floor-to-ceiling windows framing the lush green mountains of the French Indian Ocean territory.
What they may have also expected was the icy chill of air conditioning; this island just off Madagascar sits in the tropical zone to the south of the equator. But instead, the terminal is cooled by a light tropical breeze, the result of natural ventilation built into its unique design.
The genesis of the project was in 2016, as part of a wider effort by airport management to reduce its carbon dioxide emissions. Marc Delanoë, who was then leading the airport’s environmental and energy team, was determined from the beginning that the new arrivals terminal, which was being built completely from scratch, would not use air conditioning.
“I took on the responsibility to prove to my management that not using air conditioning was feasible,” said Delanoë, now the airport’s sustainable development director. “So, from the start, we never thought of this building having air conditioning being an option. It was a risky bet, but the further we went with our studies, the more we realised that we were right.”
The roof of the terminal, which opened in 2024, curves upwards from each of the rectangular building’s long sides in gentle waves. But, instead of meeting in the middle, the roofs end abruptly to form a “canyon”. The creation of an area of low pressure funnels wind into the building through vents on each side that are adjusted depending on the weather conditions.
Ceiling fans with a 7.5-metre (24.6ft) diameter help to circulate the air. In the 30C (86F) humid heat of Réunion’s wet summers, which last from around November to April, the resulting breeze reduces the perceived temperature by four to five degrees, to almost the same level usually set for air conditioning.
Less air is allowed to flow in during the island’s dry winters, when the coastal daytime temperature falls to 25C and below. During a cyclone, the entire building is closed up.
The building’s lead architect, AIA Life Designers, said it wanted to challenge the assumption that adjusting temperature was the only way for humans to cope with heat.
“It is precisely this pitfall – understanding summer comfort solely through the lens of indoor temperature – that we want to dismantle, a pitfall that traps us in the logic of air conditioning as the only answer to comfort requirements,” said Éric Bussolino, the firm’s engineering and environment director.
“Our objective is to maintain an indoor air temperature identical to the outdoor temperature while generating an airflow of 1 metre per second to reduce the perceived temperature for passengers.”
AIA, chosen for its expertise in designing airport buildings, partnered with a local architect, Olivier Brabant, who had the necessary expertise of designing buildings for the island’s tropical maritime climate, Delanoë said.
Local architects were already using natural ventilation on the island, in everything from offices and libraries to a university amphitheatre designed by Brabant. “We simply had to change the scale,” Delanoë said.
“You have to channel the air, play with the elements … That’s exactly what our ancestors did on La Réunion,” he said. “They built houses according to the direction of the wind, with a central corridor, and they opened the windows or closed the doors depending on the amount of air that they wanted to let in. If they were cold, they closed them; if they were hot, they opened them.”
Building the arrivals terminal cost €75m , of which €15m went on a new baggage sorting system and €60m on the building, said Delanoë. Since opening two years ago, the airport has saved €150,000 a year in energy bills, he said. AIA said this amounted to savings of about 60% compared with an air-conditioned building, while carbon emissions were lower by a factor of eight.
Delphine Robert, who leads the local tourism board’s welcome team, works in the terminal once a week and said she preferred it to other offices.
“It’s very airy. It’s comfortable – a lot of light, the ventilation is optimal,” she said. “I find it better working in this building, because I am often sick. And that’s the result of air conditioning, which is very strong in offices. So that’s why it’s more pleasant to work in a building where the air circulates, but it is natural.”
The lessons from the terminal’s natural ventilation will be harder to apply in large, polluted cities in mainland Europe, said Delanoë. “You will concentrate the pollutants inside – it doesn’t work,” he said. “We are lucky, we are on an island, there is no pollution around.”
Continental Europe, which is struggling to adapt to heatwaves being made ever more severe by the climate crisis, would also have to eschew air conditioning to make use of natural ventilation, Delanoë said.
“The problem is that if you have air conditioning at home and you have air conditioning in your car, when you get to the office, if you don’t have air conditioning, you’re going to be hot, he said.
“That is to say that if you reduce air conditioning throughout your life … when you get to 30 degrees in the office, you won’t be hot. In La Réunion, people are used to 30 degrees.”
