Reverberation time in class rooms – Comparison of regulations and classification criteria in the Nordic countries

Regulatory requirements or guidelines for classroom reverberation time exist in all five Nordic countries and in most of Europe – as well as other acoustic criteria for schools, e.g. concerning airborne and impact sound insulation, facade sound insulation and installation noise. There are several reasons for having such requirements: Improving learning efficiency for pupils and work conditions for teachers and reducing noise levels, thus increasing comfort for everyone. Instead of including acoustic regulatory requirements for schools directly in the building regulations, Iceland, Norway and Sweden have introduced acoustic quality classes A, B, C and D in national standards with class C referred to as regulatory requirements. These national classification standards are dealing with acoustic classes for several types of buildings. A classification scheme also exists in Finland, but with no link to the building regulations. During the last few years acoustic classification and labelling criteria have appeared also in other types of standards and schemes, among these indoor climate classification schemes with other class denotations.This paper presents the classroom reverberation time requirements and classification criteria in the Nordic countries and compares and discusses the limit values and trends.