1 Introduction The status quo of school ventilation in the Netherlands is presented (e.g. average CO2 levels in schools, quality of ventilation). In the Netherlands the most popular ventilation system for schools is exhaust-only ventilation with natural supply ventilation by means of air grilles or windows combined with convector of panel heating. 2 METHODOLOGY In a first study the goal was to evaluate the IAQ performance of exhaust-only ventilation systems. In 5 Dutch schools measurements were conducted in the heating season for a period of around 7 days. These measurements included: IAQ (CO2), thermal comfort, airflow and outdoor conditions. A logbook and questionnaires obtained information about use of ventilation facilities and satisfa...