Ganal, HelenHelenGanalBraun, MartinMartinBraunHärtel, PhilippPhilippHärtel2025-08-122025-08-122025-05-27https://publica.fraunhofer.de/handle/publica/49047210.1109/EEM64765.2025.11050173Mannheim is the first German city to announce a complete gas grid decommissioning by 2035, presenting new challenges for building stock transformation. Rising CO2 prices and grid costs threaten affordability, particularly for tenants. Using an agent-based model of Germany's building stock, we analyse behavioural responses to a proactive gas grid phase-out. Our findings show that regulatory decommissioning accelerates decarbonisation, reduces fossil fuel reliance, and avoids excessive cost burdens for vulnerable tenant segments. Policy measures lead to a 50 % increase in air- and ground-source heat pumps compared to a business-as-usual scenario, with uptake observed across all ownership groups except commercial landlords, who disregard avoided fuel costs.enbuilding stock transformationbehavioural economicsheating transitiongas grid phase-outheating sector regulationagent-based modellingconference paper