Bed-level ventilation conditions in daycare centers

In Dutch daycare centers, most often, semi-enclosed beds are used in bedrooms. Given that air usually does not mix completely in a ventilated room, there are concerns about whether room-level ventilation would be enough to keep the air clean inside semi-enclosed beds. No studies into the bed-level ventilation conditions in daycare centers have been identified. Therefore, a field survey was performed in 17 Dutch daycare centers to collect bedroom ventilation conditions and occupants’ characteristics. Based on that information, a full-scale bedroom identical to that of typical daycare centers was constructed in a climate chamber. The bed-level ventilation conditions were investigated by examining the dispersion and inhalation of CO₂ gas exhaled by a breathing thermal baby model while sleeping in a bed. The effect of three variables, i.e., sleep positions (supine, lateral-to-wall, lateral-to-corridor), baby ages (12- and 30-month-old), and ventilation rates (55 and 250 m³/h), were studied. The results showed that excess exhaled CO₂ concentration was accumulated inside the semi-enclosed bed in most cases. This indicates that bed-level ventilation conditions are not sufficient enough when only relying on the room-level mixing ventilation mode. The inhaled CO₂ concentration of infants sleeping inside the bed was remarkably high, on average, three times higher than the measured values in the room exhaust. The study provides knowledge on the bed-level ventilation conditions in miniature semi-enclosed sleeping spaces under a mixing ventilation mode at room level and highlights the need to improve the air quality inside the baby bed.