Multi‑energy systems in dense urban building clusters: a systematic review and roadmap toward sustainable built environments

• PRISMA–based review of 142 studies on dense urban multi–energy systems. • Eight parameters and four Connectors define the conceptual Urban Multi–Energy framework. • A KPI-oriented roadmap links planning, storage, policy and spatial design for deployments. Mounting climate challenges and surging urban energy demand underscore the need for holistic solutions in high-density building clusters. This review develops a conceptual Urban Multi-Energy Framework (UMEF) that integrates technical, economic, policy, and social dimensions and explicitly couples planning and operations via four mnemonic Connectors (Red/Blue/Green/Orange). Using a PRISMA–guided search across 2014–2024; a two–stage screening identified 142 studies. Analysis of these works distil eight key parameters (digital & intelligent technologies, energy storage, spatial, environmental, policy, economic, resilience, and social & behavioural) that structure the conceptual UMEF. Findings highlight how policy incentives, stakeholder engagement, and Artificial Intelligence (AI) driven analytics can collaboratively mitigate grid resilience challenges, intermittency, and carbon emissions. Further, the review underscores the importance of demand-side management, spatial planning, and cross-sector coordination in establishing robust, adaptive energy ecosystems. Building on these insights, a phased roadmap—encompassing short-term predictive analytics, medium-term pilot projects, and long-term policy integration—guides future research and implementation. By aligning engineering innovations with community acceptance and institutional support, UMEFs hold significant promise for sustainable, low-carbon transitions in densely built environments worldwide.