Studies have repeatedly shown that ventilation in schools is inadequate, with carbon dioxide concentrations in the air often reaching unhealthy levels. This affects students’ ability to concentrate. Ventilation concepts are therefore one of the top concerns in the energy-oriented refurbishment of schools. In a joint project, researchers developed two innovative ventilation concepts involving a combination of natural and mechanical ventilation.

A control system automatically optimises the operating mode. Whenever the weather, outdoor noise levels and comfort in the room permit, natural ventilation is used. Mechanical ventilation only takes over, or helps out, at other times. Automated opening systems were tested and a control system developed in a project carried out by Fraunhofer IBP in the town of Holzkirchen in Bavaria/Germany. A project in Berlin operated by RWTH Aachen University used automatic windows together with decentralised ventilation devices installed in a school’s facade elements. Industry partner Wildeboer Bauteile GmbH developed a new device for this purpose that is designed specifically for use in schools.

Some special conditions occur in schools that are not found in other buildings. Unlike offices, classroom space is used so intensively that tables and chairs are often placed very close to radiators and windows. Conventional window ventilation is impaired as a result. At times, rooms tend to be too cold in winter and too warm in summer. Students’ body heat can supply a large part of the required heating energy. When solar irradiation is added to this, the required heat output fluctuates greatly. Because of their dense occupancy, classrooms require much more intense ventilation than offices or homes.

But ventilation in schools is not just about air quality. It’s about the indoor environment as a whole. As well as thermal and acoustic comfort, this includes user behaviour, learning conditions, energy usage and practicality. Every school refurbishment project provides many opportunities for improvements. Creating efficient school buildings with a high level of user comfort is therefore a focus of energy research projects supported by the German Federal Ministry of Economics and Technology (BMWi).