Prospects of reactivating historical stack ventilation systems in schools – a measurement analysis.

Stack ventilation systems were installed in German schools constructed around 1900 but are no longer in operation. The aim of this study was to show how reactivating these systems could improve the IAQ in classrooms. Old stack ventilation systems were put into operation again in three classrooms in a school. A fourth with window ventilation served as a reference case. All classrooms were measured for CO2 levels, air temperature and relative humidity. During the winter, 50% of all measured CO2 values for window ventilation were higher than 1800 ppm. Rooms with stack ventilation showed median values of 1600 and 1350 ppm respectively. In the classrooms with stack ventilation, the air volume flow per person was ap-proximately seven times higher as with window ventilation. The revitalisation of stack ventilation provides the potential to improve the IAQ. Automated flaps to close the shafts at night and during flow reversal in summer could allow the systems to meet today’s energetic and hygienic requirements.