Integrated assessment of ventilation strategies for exposure and comfort in a multi-bed negative-pressure isolation room

• Three ventilation strategies compared under matched conditions in a two-bed NPIR. • Exposure and thermal comfort assessed together in a shared negative-pressure ward. • Air curtain strongly reduced cross-contamination but raised draft at higher ACH rates. • Mixing and displacement showed persistent limits in controlling localized exposure. • Comfort metrics (PMV, PPD, DR, ADPI) quantified performance across all strategies. Airborne cross-contamination in multi-bed negative-pressure isolation rooms is difficult to control, because even high ventilation rates cannot fully prevent the short-range airflow patterns that carry exhaled air from one patient to another. This study examines how three common ventilation strategies (mixing, displacement, and air-curtain ventilation) affect patient-to-patient exposure and thermal comfort when tested under the same room layout and boundary conditions with different nominal ventilation rates (12, 18, and 24 ACH). Two separate respiratory sources were analyzed in the patients’ breathing zones, and comfort was assessed using PMV, PPD, draft rate, and ADPI. The air curtain system created a clear airflow barrier between beds and produced the lowest exposure levels, although higher flow rates increased draft and reduced comfort. Mixing ventilation provided the most even temperature and velocity distribution but spread contaminants more widely. Displacement ventilation showed mixed behavior, with lower mixing near the floor but uneven exposure at low ACH. This study addresses a gap in the existing literature by offering the first direct, side-by-side comparison of these ventilation strategies in a multi-bed negative-pressure room under matched conditions, considering exposure and comfort together rather than separately. The results highlight the trade-offs between infection control and comfort and provide practical guidance for selecting ventilation strategies in shared isolation spaces.