## 2 Materials and Methods
### Smart Ventilation and Suppression Mechanism  
Upon detection of a fire event by the hybrid sensor and edge AI module, the system initiates a coordinated ventilation and suppression sequence to optimize smoke extraction, maintain visibility, and contain the spread of fire. This response is enabled by two key physical subsystems: (i) a motorized ceiling diffuser array integrated with an energy recovery ventilation (ERV) system for dynamic airflow control, and (ii) a precision-guided suppression unit deploying a residue-free clean extinguishing agent for effective, non-damaging fire mitigation. The structural configuration of these subsystems is illustrated in Figure 2, which presents exploded and cross-sectional views of the integrated ventilation-suppression module. The left-hand perspective view depicts the assembly layout, including the motorized diffuser vanes, nozzle housing, ERV components, and exhaust ducts. The right-hand cross-sectional view reveals the directional airflow driven by the ERV fan and the placement of the suppression nozzle within the airflow path. This integrated architecture enables simultaneous extraction of smoke and targeted discharge of a residue-free clean extinguishing agent, effectively mitigating both thermal and visual hazards during the early stages of a fire. Detailed component specifications and mechanical parameters are provided in Appendix A.  
Figure 2: Exploded and sectional views of the integrated ventilation–suppression module. This figure illustrates the internal structure and airflow mechanism of the proposed integrated fire response module. The left-side exploded view depicts the assembly layout of key components, including the motorized diffuser vanes, clean agent discharge nozzle housing, energy recovery ventilation (ERV) unit, and exhaust ducting. The right-side sectional view visualizes the guided airflow pathway driven by the ERV fan and the positioning of the residue-free clean extinguishing nozzle within the stream. This integrated configuration is designed to enable simultaneous smoke extraction and targeted suppression, effectively mitigating visibility and thermal hazards during the early stages of a fire. The motorized ceiling diffusers serve as dynamic air control interfaces that transition from a closed, energy-conserving state to an open, exhaust-facilitating state upon activation. Each diffuser is equipped with a compact servo actuator capable of 90\({}^{\circ}\) to 135\({}^{\circ}\) rotation, which reorients the discharge vanes to form a directed airflow path. This rotation is automatically controlled via a signal from the edge processor, ensuring immediate deployment upon detection. The diffusers are zonally distributed and can be selectively activated based on the location of the fire source, allowing for localized response and minimization of negative pressure zones in unaffected areas. The diffusers are mechanically coupled to a centralized ERV unit designed to initiate high-efficiency smoke extraction. The ERV integrates a high-speed brushless DC fan, heat exchange core, and HEPA-class filtration system, enabling it to perform both smoke evacuation and energy recovery functions. During fire response, the ERV operates in exhaust-dominant mode, rapidly reducing particulate concentration and temperature in the fire zone while simultaneously preserving thermal energy to maintain HVAC stability in adjacent spaces. Empirical airflow tests confirm a maximum evacuation rate of 550 CMH (cubic meters per hour) per zone, with smoke clearance within 90 s under standard test fire loads. Complementing the ventilation subsystem, the localized fire suppression unit features a 360\({}^{\circ}\) motorized nozzle paired with a pressurized reservoir containing a residue-free clean extinguishing agent. The nozzle is mounted on a gimbal platform and driven by a dual-axis stepper motor system, allowing for precise directional targeting based on real-time input from the detection module.