Modelling the complexity of interconnected energy systems at different urban scales: a critical review

The urgent need to reverse global climate change necessitates rethinking the design and operation of human-made systems. Urban energy systems, a major source of greenhouse gas emissions, are a key focus to enhance sustainability. Addressing challenges such as renewable energy integration, energy storage, reducing building energy consumption, innovative mobility systems, and improving energy infrastructure flexibility drives the development of reliable, multi-scale models capable of capturing complex dynamics. This review evaluates the current state of urban energy modelling from a novel perspective, focusing on interactions across different scales: end-users, buildings, and districts/cities. It critically assesses existing models' strengths and limitations in addressing the complexity of urban energy systems, identifying gaps in the literature and highlighting emerging trends. The review underscores a paradigm shift towards more end-user-centric modelling approaches, which aim to better capture human behaviour and its impact on energy use. Additionally, it stresses the growing demand for integrated, interdisciplinary simulation tools to address challenges such as demand flexibility. The findings advocate for next-generation urban energy models to move beyond building-focused perspectives, adopting approaches that emphasise end-users and their interactions with clean, affordable energy hubs. The review outlines future directions to improve model accuracy and scalability, supporting the transition to sustainable and resilient urban energy systems.