Italian studio Carlo Ratti Associati is among four winners of the global Helsinki Energy Challenge, with a proposal to create island-like, floating seawater reservoirs that would store heat to help decarbonise the city's heating network.
The international Helsinki Energy Challenge was launched in 2020 to unearth sustainable alternatives for urban heating networks, using Helsinki as a testbed.
Officials in the Finnish capital intend to use the winning solutions to reduce the city's dependence on coal and biomass, in order to meet its target of carbon-neutrality by 2035.
Floating islands will store heat for winter 
Carlo Ratti Associati's design, named Helsinki's Hot Heart, comprises 10 floating reservoirs that are filled with hot seawater, mimicking a small archipelago. The system would use seawater heat pumps to convert mainly carbon-free electrical energy from sources such as wind and solar power into heat. The circular basins would then work together like a giant thermal battery, storing the heat that has been converted from renewable energy so that it is readily available for district heating in the winter.
Four of these reservoirs will also be covered by inflatable roof structures to create a series of enclosed recreational spaces.
Top image: Helsinki's Hot Heart will resemble a group of islands. Above: it will double as a public recreational space
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