The Italian standard on classroom acoustics UNI 11532-2:2020 explained through case studies

The Italian Standard UNI 11532-2:2020 states acoustics requirements for classrooms and ancillary spaces, such as libraries, gyms, and canteens. Five years after its release, this paper aims to present the standard through case studies, from design procedures to in-field measurements. The UNI 11532-2 considers active classrooms, asking designers to account for the occupancy's acoustic absorption to achieve a reverberation time range across frequencies. Moreover, adequate speech intelligibility is needed in unoccupied conditions. The two requirements, intelligibility and reverberation, require appropriate choices regarding the placement of acoustic treatments. Among other solutions, mixing the materials in the ceiling becomes crucial to fulfilling these requirements. Starting from case studies - a secondary school classroom, a university lecture hall, and an innovative learning space- we present design solutions to reach the targets, providing more general considerations on common issues in classroom acoustics. The ratio N/A - where N is the occupancy and A is the equivalent absorption area in occupied conditions- has been proposed as a valuable criterion for guiding the design process. Results also show that achieving targets in the 250 Hz octave band can be challenging due to the intrinsic limitations of materials and the acoustic field in small- and mid-sized classrooms, yet maintaining the proper spatial distribution of teachers' speech levels.