<p>In hot and humid climates, the application of conventional radiant cooling systems is often limited by condensation risk and insufficient cooling capacity. To address these limitations, a decoupled radiant cooling (DRC) technology has been developed, in which a new type of radiant cooling panel is adopted. The new panel, titled as DRC panel, uses an air layer that is sealed by an infrared-transparent membrane to separate its radiant cooling surface from the air-contact surface. This design enables high radiant cooling capacity while minimizing the risk of condensation. However, existing research mainly focuses on the thermal performance analysis of DRC systems using steady-state models. There is a lack of research on their dynamic behavior under varying external boundary conditions and internal load disturbances. This study addresses the research gap in the dynamic thermal performance analysis of DRC systems by developing a quasi-2D dynamic model using a resistance-capacitance (RC) thermal network, calibrated through a non-dominated sorting genetic algorithm II (NSGA-II). The model was validated against experimental data, achieving mean absolute errors (MAE) and root mean square errors (RMSE) not exceeding 0.28 °C and 0.34 °C for both the membrane surface temperature and the radiant cooling surface temperature. The model also showed reasonable agreement in predicting the indoor air temperature and outlet water temperature. A simulation platform based on the developed model was constructed for a typical office conditioned by a DRC system, demonstrating its effectiveness as a tool for analyzing the dynamic thermal environment. The results highlight the model’s ability to provide accurate predictions, laying a solid foundation for future studies on energy consumption forecasting and operation control method development for DRC systems.</p>