Investigation into the Impact of Enclosure Retrofit on Thermal Comfort in Semi-Open University Space

The retrofit of semi-open transitional spaces in university buildings is essential for enhancing both thermal comfort and energy efficiency. However, most studies have focused on conventional indoor environments, overlooking the unique thermal characteristics of semi-open spaces and their impact on occupant comfort. This study integrated field measurements, occupant surveys, and AirPak simulations to develop a three-tier evaluation framework covering environmental parameters, subjective thermal perception, and simulation-based validation. Focusing on teaching buildings at Zhejiang University’s Zijingang Campus, the analysis revealed that the retrofit increased the daily mean air temperature by 2.1 °C and decreased the relative humidity by 3.6% in winter. The peak thermal comfort indices PET and PMV improved by 4.4 °C and 0.98, respectively, with a neutral PET identified at 13.3 °C. PMV showed a stronger correlation with TSV (p = 0.94, R2 = 0.81) than PET. Simulations further validated the retrofit’s effectiveness in stabilizing the indoor thermal environment and reducing airflow discomfort. These findings provide both theoretical insights and practical guidance for the climate-responsive, energy-efficient retrofitting of campus buildings in hot summer and cold winter (HSCW) zones.