<p>Double-skin façade (DSF) systems have emerged as a promising architectural strategy for improving thermal performance by reducing heating and cooling loads while enhancing occupant comfort. However, their effectiveness can vary depending on outdoor climatic conditions. In particular, insufficient air circulation within the cavity may lead to excessive heat capture, resulting in overheating, increased cooling loads, and diminished occupant comfort. To address these limitations, this study proposes an IoT-based smart double-skin façade (SDSF) system capable of dynamically regulating cavity thermal conditions. A full-scale field experiment was conducted to evaluate the performance of the SDSF system in improving the indoor thermal environment of curtain wall-based building types during summer. Indoor conditions were compared between a single-skin façade (SSF) and the SDSF system under various shading and ventilation control strategies. The results demonstrated that SDSF effectively reduced daytime indoor temperatures and stabilized nighttime conditions through real-time controls of exhaust fans and blinds. Predicted mean vote (PMV) analysis also further indicated improved occupant thermal comfort with SDSF. These findings provide empirical evidence that IoT-integrated SDSF system can significantly enhance both indoor thermal comfort and energy performance, offering a viable strategy for climate-responsive building envelope design.</p>