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.