The Basic Law obliges the state to achieve climate neutrality. But within the federal system, who bears responsibility for implementing concrete measures? Lukas Muffler demonstrates that the federal legislature has meanwhile established the foundations for vertical coordination of the heat transition. As a result, the requirement of safeguarding intertemporal freedom as articulated by the Federal Constitutional Court now also applies to legislation at the Länder level. At the same time, heat planning is a mandatory task of the municipalities. For effective climate protection, this governance approach represents a milestone. Building on this finding, the author addresses the question of how municipalities can legally shape the heat transition. The relevant legal framework ranges from the 1.5-degree target under the Paris Agreement and European Union law to national constitutional law, as well as federal and Länder legislation, down to the municipal level. The central legal basis is the Heat Planning Act, which entered into force in 2024. A particular focus of the study lies on delineating regulatory competences, the instruments for implementing heat planning, and questions of proportionality. One core thesis is that heat planning has significant indirect legal effects. In conjunction with the statutory priority given to renewable energy, projects implementing the heat transition attain the greatest possible weight recognized by the German legal order beyond absolute guarantees. Heat planning is a European project that also contributes to energy sovereignty and thus to national security. Against this backdrop, the interdisciplinary study concludes that the Basic Law calls upon all levels of government to support municipalities with united efforts on their path toward a sustainable and resilient heat supply.