Performance Evaluation of Electrochromic Windows in Cold-Region University Classrooms: A Multi-Scale Simulation Study

Electrochromic windows (ECWs) are promising smart façade technologies that can enhance indoor comfort and reduce energy demands, yet their performance in university classrooms remains underexplored in cold regions. This study evaluates the applicability of ECWs in classrooms in Xi’an, a representative cold-climate city, through dynamic simulations of three classroom types. Three control strategies—based on outdoor temperature, illuminance, and solar radiation—were tested under different thresholds. The results show that compared with static windows, ECWs can increase the annual mean indoor temperature by up to 1.4 °C, extend thermal comfort time ratio by 4.5%, improve visual comfort duration by 6.3%, and reduce heating and cooling demands by 11.6 and 14.3 kWh/m2, respectively. These findings demonstrate both the feasibility and the differentiated benefits of ECWs in educational buildings, filling the research gap on their performance across different classroom types and offering practical guidance for sustainable classroom design and operation in cold climates.