A Structured Library of Local Climate and Energy Actions to Support Synergy-Oriented Sustainable Urban Planning

Local governments increasingly adopt climate and energy strategies addressing both mitigation and adaptation objectives, yet these domains are often treated separately, limiting integrated planning. This study develops a structured Climate–Energy Action Library to support more coherent local decision-making. The library was constructed through a systematic review and harmonisation of actions from European Sustainable Energy and Climate Action Plans (SECAPs), international repositories, and related frameworks, resulting in a taxonomy of 171 actions grouped into thematic bundles and policy categories. The methodology enables the identification of potential synergies among measures, and revealing consistent cross-sector interaction patterns. The strongest interaction potential occurs when technical measures are combined with enabling governance actions, including policy instruments, planning frameworks, and capacity-building. Cross-sectoral synergies are evident in building retrofit programmes linked with heat-stress adaptation and in nature-based solutions contributing to mitigation, urban cooling, and ecosystem services. These findings indicate that governance and ecosystem-based measures often enhance the effectiveness of sector-specific interventions. The proposed library provides a practical analytical reference for municipalities, supporting the design and evaluation of integrated climate strategies and helping bridge the persistent separation between mitigation and adaptation in local climate governance.