This work focuses on the ventilation control strategies employed in Amphitheater A at the Faculty of Mechanical Engineering, University of Belgrade, Serbia with a particular emphasis on occupancy-based control. Given the amphitheater's high occupancy capacity of up to 500 people and variable usage patterns, designing an efficient ventilation system is essential for maintaining optimal indoor air quality and minimizing energy use. The study explored the implementation of Constant Air Volume (CAV) and Variable Air Volume (VAV) systems, with ventilation controlled by mean indoor air temperature and CO₂ concentration. Various occupancy scenarios were simulated using the IDA ICE software to assess how each control strategy maintains indoor air quality under different conditions. The simulation results revealed significant differences in the performance of the CAV and VAV system. The VAV system, particularly when controlled by temperature allowed for precise adjustments of ventilation rates based on real-time usage, reducing energy use during periods of lower occupancy. In contrast, the CAV system, while maintaining constant airflow, showed higher energy use, due to its inability to adjust dynamically to change in occupancy levels. Overall, this paper provides valuable insights into the benefits of demand-controlled ventilation based on occupancy in large spaces.