Designing for Acoustic Comfort in Educational Spaces

Acoustic Requirements in New Zealand Schools

In Aotearoa, the Ministry of Education outlines a set of mandatory requirements for acoustics in education that address four key issues:

• Reverberation Time (RT): The time it takes for sound to fade away in a space after the source has stopped.
• Sound Transmission Class (STC): A rating that measures how effectively walls or partitions block sound between spaces.
• Impact Insulation Class (IIC): A rating that measures a floor’s ability to reduce noise from impacts, like footsteps.
• Indoor Ambient Noise Levels: The background noise present in a space from sources like HVAC systems or outside traffic.

When it comes to refurbishments, the recommended acoustic strategies generally align with those used for new buildings, as there is usually room for improvement during any upgrade. If significant changes occur—such as alterations to layout, occupancy or activity types—or if the existing acoustic conditions present significant issues, the standards set by MOE should be adhered to as much as reasonably practicable.³ 

Effective Acoustic Design Strategies

The Ministry of Education also provides a series of tips and guidelines for acoustic design in education, including: 

Acoustic distribution
 
Acoustic materials should be well distributed throughout a space for effective sound absorption. If acoustics are applied only to one surface, sound will reverberate off the other hard surfaces making for a higher RT (reverberation time) and possible echoing.

Ceilings and walls

Ceilings should be treated with highly absorptive products (NRC 0.85 or higher) as well as the majority of available walls space.

Vary the thickness of acoustic treatments

Different frequencies of noise are absorbed by differing thicknesses of materials. For example, low frequency noise is only absorbed by materials of 40mm or thicker. Thin materials, such as carpet and acoustic pinboards, only absorb higher frequencies. In order to achieve a balanced RT (reverberation time) spectrum, a combination of varying thicknesses of acoustic material applications is recommended.

Strategic placement of glass

Many classrooms have glass windows and wall partitions which provide an essential view to nature and natural light. Proper design consideration should be given to the size and placement of glass panels as glass can pose acoustic issues due to its sound-reflective qualities.

Door and window positioning

Doors and windows that are positioned within an acoustically rated wall will degrade its acoustic performance- these should be carefully positioned. Selections for door materials, seals and joinery are then naturally important.

Sliding doors

Sliding doors are a preferred solution for large learning spaces, however, they have poor acoustic performance and should only be used in spaces where teachers require flexibility to be able to adapt the size of the teaching space. Teaching staff should be made aware of the acoustic compromise and determine the most appropriate solution.

Floor and ceiling treatment

Selecting appropriate floor covering and ceilings is important for achieving the minimum IIC requirements. Hard flooring and exposed soffits can make meeting compliance difficult but there are solutions, such as acoustic backed carpet tiles, that can help.