District heating is gaining prominence in the energy transition thanks to its ability to integrate renewable sources and waste heat, cut emissions, and improve efficiency. With smarter, more flexible networks, it can become a cornerstone for resilient and sustainable cities.
District heating systems, with over 150 years of history, are evolving into flexible infrastructures capable of integrating multiple energy sources and storage to meet both heating and cooling needs. Today, this technology supplies around 10% of global building heat demand, with particularly high penetration in Northern and Eastern Europe and in China; emerging markets in Canada and Ireland are also taking off. Although 90% of these networks still rely on fossil fuels, their potential to incorporate renewable energy—such as bioenergy, solar thermal, geothermal or even nuclear—is promising, especially as improvements in low-temperature networks, substations and digital control continue.
A key aspect is recovering waste heat from sectors such as data centres, wastewater or mining, typically available at temperatures below 100°C. With heat pumps, these flows can be reused, significantly improving efficiency and reducing losses. Real examples include using data centre heat in Stockholm and Espoo, and large-scale wastewater projects in Qingdao and Hamburg.
These systems can also absorb surplus renewable electricity through large heat pumps or electric boilers, acting as seasonal thermal storage and grid stabilisers. The integration of smart meters, digital twins and advanced controls optimises their response to demand and market signals.
Achieving all this requires comprehensive heat planning (including mapping, appropriate tariffs and well-defined zones) and regulatory frameworks that support electrification and waste heat recovery. District heating not only reduces emissions and local pollution but also strengthens cities’ resilience to current energy challenges.
