The low-carbon renewal of school campuses is increasingly central to sustainable urban development, particularly in regions where existing public-building stock must be upgraded under climatic and topographic constraints. This paper presents a structured case study of Yezhai Middle School in Tianzhushan Town, Qianshan, Anhui Province, China, and frames the project as a smart-city public-infrastructure retrofit problem. The study integrates site planning, wind-environment simulation, facade regeneration, and exterior-wall thermal analysis in order to establish a practical method for upgrading mountainous secondary-school campuses. A simplified geometric model of the school complex was developed in SketchUp and analyzed in Ecotect using the WinAIR plugin. The wind model employed a 5 m/s inlet wind speed, 0 Pa outlet pressure, no-slip wall boundaries, an ambient temperature of 30∘C, air density of 1.2 kg/m3, and air viscosity of 1.8 × 10−5 Pa⋅s, with sectional analyses at 0, 10, 20, and 30 m. Field validation at four measurement points showed close agreement between measured and simulated wind speeds, with relative errors ranging from 3.13% to 6.67%. Thermal assessment of the renovated exterior wall adopted a 20∘C indoor–outdoor temperature difference and a high-density expanded polystyrene (EPS) insulation layer of 0.15 m thickness with thermal conductivity of 0.038 W/mK. The calculated wall U-value was 0.253 W/m2K, and the annual post-renovation winter heat demand was 2920 kWh. The facade strategy combined energy-saving wall improvement with campus-wide visual unification, gray-and-white material control, and a Hui-style architectural language. The study demonstrates that simulation-led retrofit design can improve outdoor wind conditions, reduce heat transfer, and provide a replicable planning framework for school renewal within the broader agenda of urban sustainability and smart-city infrastructure.