Evaluating green urban underground spaces using PROMETHEE II for ecological suitability

The ecological suitability of urban underground spaces (UUS) is critical to sustainable urban development. This study develops a PROMETHEE II-based evaluation framework to assess UUS projects by integrating environmental, economic, and social criteria. A structured survey involving 25 experts was conducted to determine the relative importance of 11 sustainability criteria, with energy efficiency (18%) and carbon footprint reduction (16%) identified as the most influential factors. The PROMETHEE II method, which provides a complete ranking based on net preference flows, was applied to evaluate five real-world UUS projects in China. The underground green park (Φ = 0.82) emerged as the most sustainable alternative, while the multilevel parking facility (Φ = 0.54) ranked lowest due to high construction costs and limited environmental benefits. PROMETHEE II enabled the apparent prioritization of alternatives, thereby enhancing the model’s decision-support capacity. The findings highlight the importance of integrating green infrastructure and transit-oriented underground developments to improve urban sustainability. This framework provides urban planners with a practical tool for aligning future UUS projects with ecological and sustainable development objectives.