Impacts of Urban Vegetation on Cooling Energy Demand Across 100 Global Cities

Urban trees are widely promoted to mitigate urban heat and reduce cooling demand through shading and evapotranspiration. However, added moisture can increase dehumidification energy loads, making the net impact of greening on building energy demand climate-dependent and poorly quantified. Here, we use the Urban Tethys-Chloris model coupled with a Building Energy Model (UT&C-BEM) to quantify vegetation-driven impacts on summer air-conditioning energy consumption (EC_AC,summer) in 100 globally significant cities spanning diverse climates, urban forms, and vegetation patterns. Under present-day vegetation cover, urban trees reduce mean daily summer cooling energy demand in all 100 cities, but with a clear trade-off between absolute energy savings and relative sensitivity of savings to green area. By systematically increasing tree fraction from each city’s baseline up to 100% cover, we found that greening efficiency is highest in hot arid cities and markedly weaker in hot humid climates, where enhanced dehumidification demand offsets sensible cooling benefits. Cities in hot arid climates, where greening efficiency is highest, should prioritize tree-based cooling as a cost-effective energy mitigation strategy.