Multi-Objective Optimization of Urban Greening Strategies in Hot Climates: An Integrated Framework for Environment, Energy, and Economy

Rapid urbanization has intensified ecological challenges, including urban heat islands, energy consumption, significantly impacting socioeconomic outcomes. Greenery strategies, such as tree and grass integration, can enhance cooling effects, improve thermal comfort, and reduce energy consumption, effectively mitigating urban environmental issues. Therefore, optimizing and quantitatively integrating greening strategies under limited land resources is crucial. This study develops a multi-objective optimization model and an integrated assessment framework for urban greening strategies in hot and humid climates. The framework considers three key indicators: environmental performance, energy efficiency, and economic benefits, aiming to identify the optimal greening configurations over its lifecycle and assess its holistic impact on high-density city. The study employs ENVI-met for simulating vegetation-induced thermal effects, EnergyPlus for building energy performance analysis, and NSGA-2 for multi-objective optimization. A multi-criteria decision-making approach is used to determine the optimal design scheme. The proposed framework was applied to a high-density residential community in Singapore. Results indicate that different green configurations and layouts result in performance deviations ranging from -8.34% to +22.17%.Morris sensitivity analysis identifies GCR (Green Coverage Ratio) and LAI (Leaf Area Index) as the most influential factors affecting greening performance. The optimized design favors larger tree canopies, higher LAI values, and an orientation from south to southwest. Compared to the baseline model, the optimized scheme achieves a 38.57% reduction in outdoor thermal discomfort and a 12.34% reduction in energy consumption while maintaining economic feasibility. This framework provides practical guidance and a decision-making tool for optimizing urban ecological design, assisting urban planners in balancing environmental and economic benefits. Furthermore, it highlights the critical role of greening strategies in addressing rapid urbanization and climate change challenges.