The indoor quality of an occupied space is very important for the well-being of its occupants, especially in the case of young children. The poor condition of the indoor environment in almost 80% of the Dutch classrooms has led to the drafting of a program of demands for fresh schools. Following this program of demands should improve the cognitive performance of the pupils. This program of demands is currently only available for the accommodation of primary schools whilst a healthy indoor environment for younger children (age 0-4) is just as important. The body of a young child is under development and adverse conditions could affect this development. Also little children spend a lot of their time in daycare centers while parents are at work, while little is known about the effects of different indoor environmental factors present in these daycare centers and the quality of the buildings in which these daycare centers are accommodated. As the Indoor Air Quality is very important for the infants measurements were done and especially is looked at the influence of the type of baby kot on the ventilation effectiveness, something what is normally forgotten. During several weeks measurements were performed in a daycare center to get a good detailed overview of the specific circumstances. It proved that the type and location of the baby cot has an important influence on the effectiveness of the ventilation.