Yilin Cen

Commercial plots in hot–humid tropical island cities require effective pedestrian-level ventilation; however, the extent to which different layout forms enhance wind-driven cooling potential under fixed development intensity remains insufficiently quantified. Taking Haikou as a representative tropical island case, this study examines how building count and spatial enclosure form affect the pedestrian-level wind environment of a commercial plot. A total of 63 layouts with one, two, and three building units were constructed under identical development constraints. ANSYS Fluent 2023 R1 (ANSYS, Inc., Canonsburg, PA, USA). was used to simulate pedestrian-level wind fields under representative summer southerly and east–northeasterly (ENE) wind conditions. Six ventilation-related indicators, including area-weighted mean wind speed, maximum wind speed, and the non-low-wind-speed area ratio in both seasons, were integrated into a Wind-Driven Cooling Potential Index (WDCPI). The weighting scheme combined climate-informed seasonal weights with entropy-based objective indicator weights. The results show that summer ventilation is more sensitive to layout form than winter ventilation. Although the average WDCPI decreases as building subdivision increases, layout B2 shows the highest WDCPI among the tested scenarios because its open inter-building space forms a continuous ventilation path aligned with the prevailing summer wind. The sensitivity analysis supports the relative stability of the ranking results. These findings highlight airflow connectivity and windward openness as important layout-screening principles for cooling-oriented commercial plot design in tropical island cities.

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.