When the Soviet Union collapsed in 1991, it left behind an unexpected gift for the climate change era. Underneath the towns and cities of Eastern Europe, Soviet planners designed vast networks of pipes that carried steam and hot water to homes, schools, shops, hospitals, and more. These centralized systems—turned on and off by officials—provided cheap and universal heating across entire municipalities. Thirty years after independence, despite serious declines in service due to underinvestment, district heating still makes up the lion’s share of heat generation in Estonia, Lithuania, and Slovakia. In Ukraine, as of 2021, 53% of urban households still relied on it, according to data shared with TIME by engineering firm Tetra Tech’s Ukraine energy security project.
That’s a big advantage in the energy transition. Though the water in district heating networks is usually warmed by coal or natural gas plants, it is relatively easy to adapt them to run off bioenergy or waste heat from sewage systems, electric power stations, or even data centers. That’s much simpler, cheaper, and potentially more energy efficient than replacing thousands of fossil-fueled boilers across a neighborhood. In Western Europe, where centralized heating networks are less common, cities are racing to develop them. They can learn from Ukraine: in recent years climate-conscious foreign donors have been retrofits of ailing systems in towns like Kyiv, Zhytomyr, and Kremenchuk, as models of what is possible.