Underground 'Lake' Helps Cool Helsinki as Demand for District Cooling Rises

Underground reservoir keeps Helsinki cool through summer heatwave

A vast cold-water reservoir hidden beneath Helsinki’s Esplanade Park is helping the city combat rising summer temperatures. The underground site, managed by energy provider Helen, holds around 25 million litres of chilled water and supplies cooling to hundreds of buildings. Often called a "lake" due to its size, the tank forms part of Finland’s growing district cooling network.

Underground 'lake' helps cool Helsinki as demand for district cooling rises

Finland is in the midst of a record-breaking heat wave and Helsinki's subterranean reservoir helps cool off over 500 buildings in the city's system.