Indoor Air Quality and thermal climate in schools is problematic in many countries. The status quo in the Netherlands is presented (e.g. average CO2 levels in schools, problems with ventilation). The goal of a first study was to evaluate the performance of exhaust-only ventilation systems. In a following study, 6 schools with different ventilation systems were studied. Main conclusions from these studies were: IAQ in the evaluated schools did not meet the requirements and more ventilation was essential for better IAQ. A new integrated approach, to design adequate solutions for ventilation of school buildings was developed. First results are described in the paper