Decarbonising the Heat: What European City Case Studies Reveal About Fossil Fuel Phase-Out

This session draws on the EU Covenant of Mayors' Cities Heat Detox campaign, 55 case studies across 22 EU countries (2024–2025), to present one of the most compriehensive evidence sets on city-led fossil fuel phase-out in buildings.

Cases range from Vienna's city-wide gas phase-out (eu-mayors.ec.europa.eu/en/vienna-s-heat-detox-for-an-even-happier-city), to Marseille's seawater-based district cooling, as well as experiences from Vajxo and Cascais. The session extracts transferable design principles: when does district heating work versus building-level solutions? What financing models scale? How does citizen engagement shape outcomes?

The evidence base spans cities of all sizes, from large capitals to small towns, explicitly addressing the financing and governance barriers that affect less-resourced municipalities most. Energy poverty and affordability are treated as primary design considerations throughout.