A smart HVAC retrofit system to improve fire safety in mission-critical facilities

This study presents a simulation-based evaluation of an integrated HVAC and smoke control retrofit aimed at improving fire resilience and occupant tenability in simulated nuclear power plant Main Control Rooms (MCRs). Utilizing advanced Fire Dynamics Simulator (FDS) modeling validated against NRC and NIST benchmark data, the proposed system incorporates a ceiling-mounted exhaust-only configuration, a non-invasive retrofit strategy leveraging existing infrastructure, and novel features such as an automatic smoke control curtain and active cooled makeup air supply. The ceiling-mounted exhaust-only design demonstrated superior smoke extraction efficiency compared to hybrid systems combining makeup air and exhaust, which tended to disrupt smoke layering due to turbulent airflow. The retrofit approach is minimally invasive, avoiding costly structural modifications while enhancing smoke and thermal management. Key innovations include rapid deployment of a smoke control curtain that confines hot smoke to upper zones and an active cooling system that maintains breathable air near the floor, significantly improving occupant safety and visibility. These elements operate within a closed-loop Proportional-Integral-Derivative (PID) control framework that dynamically adjusts ventilation based on real-time wireless sensor feedback. Quantitative evaluation using a Weighted Performance Index (WPI) showed that the integrated system reduced fire hazard metrics by approximately 48 % relative to conventional HVAC shutdown scenarios, with substantial improvements in smoke layer height, temperature control, and radiative heat flux resistance. The modular, scalable design offers broad applicability beyond nuclear facilities, including data centers, hospitals, and underground transit systems, providing a promising strategy for enhancing fire safety and operational continuity in mission-critical environments. • Developed a scalable HVAC retrofit framework for adaptive smoke and fire control in mission-critical sites. • Integrated feedback algorithms to coordinate smoke curtains and air supply for optimized smoke control and ventilation. • Validated control performance using FDS models calibrated with NIST and EPRI benchmark fire scenarios. • Improved smoke layer height by 148 % and fire resilience by 216 % without any structural modifications. • Modular, non-invasive system with adaptive control for critical sites like control rooms, hospitals, and data centers.