The effect of natural ventilation on the indoor air quality in classroom of the elementaryschool without heating equipments during winter season

Field survey on indoor air quality was conducted during winter season, in an elementary school at Kagoshima city. Asthe windows had been closed because of avoidingthe cold outdoor airIn thewinter,CO2 concen- trationsunder pupilsstaying in the classroom wereover1500 ppmat the end of the lesson. When the windows of the corridor facing outside had been open, the CO2 concentrations in corridor were close to the outdoor CO2 concentrations. It was found that the ventilation during the break could play an important role in CO2 concentrations during the next lesson. The CO2 emissionrate from one thirdgrader child was calculated as 0.011m3/h.In terms of the rise of indoor CO2 concentrationsince the lesson had started, it was found that the influence of the accumulation of the CO2 before the lesson on the CO2 concentrationduring the lesson was very large. The natural cross ventilation during the break of the lesson could be important. It turned out that theindoor CO2 concentration didnot exceed 1500 ppm in 75% of time of a 45-minute lesson where 39 children occupied and the air change rate was 0.6 h-1, if indoor CO2 concentration would decrease to outdoor level by opening windows during the break.