Pedestrian-Level Cooling Performance Index and Climate-Adaptive Layout of Tropical Commercial Plots Under Constant Development Intensity

In tropical island cities, the combined pressures of rapid high-density urbanization and year-round hot-humid climates make the pedestrian-level wind environment a critical determinant of outdoor thermal comfort and cooling performance. Focusing on Haikou, a tropical island city, this study optimizes building layouts on commercial plots under constant development intensity. A Pedestrian-level Cooling Performance Index (PLCPI) was constructed, prioritizing summer cooling and winter wind control through an AHP-EWM combined weighting method. The index integrates maximum pedestrian-level wind speeds and amplification factors to evaluate 65 layout configurations, including detached, row, perimeter, and courtyard types. The results reveal a nonlinear relationship between building count and cooling performance. Single-building layouts achieve the highest mean PLCPI (2.367), three-building layouts the lowest (1.825), prone to ventilation stagnation, and four-building layouts show a performance rebound (2.271) with stable efficiency. Crucially, spatial enclosure form is the decisive determinant under a constant building count: the optimal two-building layout B-8 (PLCPI=2.456) surpasses the best single-building layout A-2 (2.419), demonstrating that well-designed dispersed layouts can outperform centralized ones. This study proposes a dual-season adaptive evaluation framework for tropical commercial plots and reveals the nonlinear mechanism between building quantity and cooling performance, providing a scientific basis for fine-grained urban design in tropical island climates.