Based on the optimization of a hybrid heat source heating system integrated with interactive cascade ventilation (ICV) systems terminals under the global energy transition and the “dual carbon” strategy, this study investigates five operation strategies: PHEH, PHAP, SHAP, ISHS, and DSHS, incorporating Multistage Solar Energy Resource Utilization. The results demonstrate that PHAP emerges as the optimal strategy in cold climate zones, while maintaining the lowest annual electricity consumption 589.7 kWh. The direct solar supply mode attains a COP exceeding 8. Meanwhile, Under the climatic conditions of the Tianjin region, the PHAP mode demonstrates the optimal energy efficiency performance, reducing power consumption by 21.3–35.3% compared to other modes. PHEH mode shows weaker performance across various indicators, while the ISHS and DSHS modes utilize tank heat more efficiently, exhibiting minimal heat loss throughout the entire heating season. When the system operates in solar direct supply mode, its energy-saving performance is excellent. These findings provide a foundation for optimizing energy allocation in interactive cascade ventilation systems.