Rising River Temperatures Threaten Paris’s Water-Based Building Cooling Network

Networks of pipes and heat exchangers can transfer excess heat from buildings into nearby bodies of water — but as the world warms, the cooling potential of some water courses is now diminishing, Wired reports. Paris’s district cooling network, which pipes Seine river water to cool 800 buildings including the Louvre Museum, faces diminishing returns as climate change warms water temperatures. The system achieves coefficients of performance between 4 and 15 — significantly higher than conventional air conditioning — by transferring building heat through heat exchangers to the river. The Seine briefly exceeded 27C this summer, approaching the 30C regulatory limit for returned water.

The network currently spans 100 kilometers of pipes and will expand to 245 kilometers by 2042 to serve 3,000 buildings. Similar installations operate in Toronto using lake water from 83-meter depths and at Cornell University drawing 4C water from Lake Cayuga at 76 meters. Rotterdam and other cities are developing comparable systems as cooling demand rises.