Decarbonizing housing in polarized environments: instrument accumulation and the politics of implementation in German cities

The growing mismatch between expanding policy portfolios and constrained implementation capacity challenges the problem-solving capacity of modern states. Existing research shows how policy growth drives overload and organizational coping, but neglects how polarization reconfigures the politics of accumulation, creating distinct vulnerabilities for implementers and motivating strategies that decouple implementation from instrument objectives. This paper analyzes Germany’s heat transition, an expansion of the climate policy portfolio aimed at decarbonizing housing by 2045. It compares regulatory instruments created outside channels of vertical policy integration with the heat planning instrument, developed through vertical policy integration, across two polities and four cities. The findings show that rising polarization made it rational for ministerial elites to bypass established policymaking procedures. While this secured enactment, it carried non-decisions about task allocation and burden offsetting into implementation and failed to secure implementer buy-in. Local governments adapted regulatory instruments to polity-specific vulnerabilities and their own political priorities, decoupling implementation from intended objectives. In centralized polities, they used these instruments to expand capacity and mitigate overload; in delegated polities, to rebalance dependence on third parties. By contrast, the heat planning instrument incorporated implementation expertise, offset implementation burdens, and was implemented largely as intended.