2026 ASIAN Conference on Communication and Networks (ASIANComNet 2026)

Human presence plays an important role in the operation of HVAC systems. Traditional HVAC systems usually rely on fixed occupancy schedules, leading to a substantial amount of wasted cooling energy, particularly in tropical climate countries such as Vietnam. To evaluate the impact of occupant presence under realistic conditions, this study conducts a simulation-to-simulation (Sim-vs-Sim) case study of a typical office in Hanoi, Vietnam, using CO₂-derived occupancy schedules extracted from a two-week field deployment. Unlike a single representative day, the proposed framework is evaluated across multiple days spanning both mild and high cooling-demand conditions. Results show that the energy-saving effect of occupancy-driven scheduling is conditional on ambient cooling demand: on days with negligible cooling load, static and dynamic schedules produce identical energy use, while on the highest cooling-demand day observed, the dynamic occupancy schedule reduced total daily energy consumption by 7.51% and peak cooling load by 13.95% compared to the static baseline. These findings suggest that occupancy-aware HVAC control is most impactful during high cooling-demand periods, and that its benefit should be reported and interpreted conditionally rather than as a single aggregate figure.