Statistical analysis of natural and mechanical ventilation performance in improving indoor air quality, thermal comfort, and perceived air quality in a healthcare facility

Ventilation strategies in healthcare facilities are mainly directed towards mechanical systems. Due to patients' preferences or the necessity of terminal reheat/recool, Air Handler Units are often turned off or windows are opened when mechanical systems are active. This leads to poor IAQ, nosocomial infections, and energy loss. Besides, ventilation systems are not typically intended to optimize user satisfaction. Using field measurements in 140 spaces, survey studies, and statistical analysis, this study compares ventilation strategies in providing IAQ, thermal comfort, and Perceived Air Quality as an indicator of user satisfaction. 315 samples were collected for air velocity, air temperature, relative humidity, PAQ, odor intensity, and VOC concentrations. Lowest to highest pollutant concentrations were observed respectively in mechanical ventilation with two open windows, mechanical ventilation with one open window, natural ventilation with two open windows, mechanical ventilation with closed windows, natural ventilation with one open window, and nonventilated spaces. There was no evidence of an effect of ventilation strategies on environmental parameters and user satisfaction. Users' thermal comfort and air quality satisfaction were not guaranteed even when ventilation rate, pollutant concentrations, and environmental parameters were within the permissible range. Findings support the efficient performance of natural ventilation in providing acceptable air quality.