Under the streets of Paris, a 75-mile (120km) labyrinth of pipes is working to keep parts of the city cool, carrying water chilled in special plants to offices, malls, and museums, including the Louvre. The network, operated by Fraicheur de Paris, part of Engie SA, uses water from the Seine as part of the cooling process and is under intense strain from record high temperatures across Europe.
How the district cooling network works
The district cooling system uses refrigerants to chill water to as low as 4 C (39.2F). The water, in a closed loop system, is pumped to clients' buildings to produce fresh air. As it warms, it circulates back to plants for cooling again. Water from the Seine is tapped via heat exchangers as part of the cooling process. Fraicheur de Paris says it is more environmentally friendly, using 50 per cent less electricity than a standalone system and cutting emissions by half.
Strain from the heatwave
Managing Director Marie Carlo said chilling plants are working round the clock, but huge demand and occasional power outages mean sometimes they cannot get the water as cold as usual. Despite the stresses, Carlo says district cooling is going to become even more important as a response to climate change and more extreme weather patterns. “What used to be seen as a comfort solution is now becoming a health issue,” Carlo said this week while presenting a tour of Fraicheur de Paris’s operations. “We have a lot of demand for connections these days.”
Impact of the heatwave
The latest heatwave in Europe arrived before the usual summer temperature peak in July. In Paris, it forced the Louvre and the Eiffel Tower to close earlier than usual this week. Across the continent, transport was disrupted, crops were damaged, and schools and nurseries had to shut. The heatwave has also been linked to a number of deaths. More than 60,000 people were likely killed by scorching temperatures in the summer of 2022, and about 47,000 people in 2023.
History and expansion of the network
District cooling has been used on a small scale in Paris since the 1970s, but started to really grow in the 1990s. Since then, Fraicheur de Paris has expanded to 14 chilling plants, as well as large reservoirs and ice tanks. One facility, under the banks of the Seine near the Place du Canada, houses pumps, pipes, and machinery. There is a loud permanent buzz as chillers deep underground cool large volumes of water before sending it via scores of pipes to serve air conditioning systems of clients. Above them, heat exchangers use water from the Seine, which is regularly flushed back slightly warmer into the river.
Future plans
Fraicheur de Paris, which operates under a concession from the city, supplies more than 900 clients, from office buildings to landmarks like the Opera Garnier. It aims to add more plants and almost 100 miles of pipes to triple the number of premises connected by 2042, when its concession expires. District cooling is also being used in cities including Zurich, Singapore, and Chicago.
