Urban Heat Island Mitigation through Optimized Green-Blue Infrastructure Networks: A Multi-City Digital Twin Study

Abstract

Urban heat islands (UHIs) increase city temperatures by 2-8°C relative to surrounding rural areas, exacerbating heat-related mortality, energy consumption, and air pollution. We present a multi-physics digital twin framework that couples computational fluid dynamics (CFD), surface energy balance models, and evapotranspiration algorithms to optimize the placement of green (parks, street trees, green roofs) and blue (urban streams, fountains, permeable pavement) infrastructure for maximum cooling. Applied to 10 km² districts in Beijing, Houston, and Milan, the optimized green-blue network reduces peak summer surface temperatures by 4.2-6.8°C while reducing stormwater runoff by 35-48%. Cost-benefit analysis shows the avoided health and energy costs exceed infrastructure investment within 7-12 years.