With this year’s UK Disability History Month focusing on children, learn more about how to achieve good acoustics in schools
This year’s UK Disability History Month is focusing on children, and encourages everyone from councils, service providers, education establishments, youth, play and sports organisations, health providers and even those in the built environment to examine their approaches to disabled children and youth. Inclusion and accessibility must therefore be at the heart of all stages of design.
Acoustics, regarded by many as a niche specialism, can all too often be overlooked in the (inclusive) design process. Architects might design a whole building around glazing to maximise daylighting, while discussions about improving the sensory experience of noise for occupiers are sometimes not, well... heard.
Helen Taylor, Director of Practice at Scott Brownrigg and a passionate advocate of inclusive design, suggests that acoustic considerations are only applied as a stuck-on element at the end of a project, or is seen as a target for ‘value engineering’. This despite well-considered acoustics being recognised as critical to the effective functionality of a space and our health and wellbeing.
In public buildings, busy workspaces and transport hubs, inclusive design considerations can also include access to dedicated quiet spaces.
‘Despite the clear evidence, we have a tendency as architects to focus our efforts on visual and spatial matters and to award buildings that just look great,’ says Taylor.
What requirements exist for acoustics in schools?
One standout building type where acoustics do get proper attention, because performance standards are mandated by Building Regulations and the Department for Education for centrally funded development, is schools. The standards emerged from longstanding research studies showed that acoustic standards can have a direct impact on educational attainment.
Poor acoustics in schools can reduce speech intelligibility, making it more difficult for students to concentrate, and puts a strain on teachers’ voices. Impact can be greater for pupils with special educational needs, and those who are hard of hearing or have communication access needs, Taylor points out.
In 2003, Building Bulletin 93 set out performance standards for acoustics in schools (under regulation E4 of the Buildings Regulations) leading to a significant improvement in the acoustic conditions of new school buildings. In 2015, BB93 was revised and introduced additional criteria for refurbished school buildings – less onerous than new-build, but still delivering acoustic conditions favourable to teaching and learning.
BB93 covers a number of aspects for acoustics in schools, including room acoustics, internal ambient noise levels, internal airborne and impact sound insulation, and rain noise.
What are the key principles for designing for good acoustics?
With legislation in place, the acoustic characteristics of a space should then be considered.
Reverberation or room acoustics is the way a room sounds and could be described as ‘lively’ when a person can hear sounds reverberating around the space (extreme examples are swimming pools and large warehouse spaces), or ‘dead’ where there is little or no observable reverberation, explains Daniel Oldaker, Director at Acoustic Consultants Ltd. Examples of dead spaces include conference rooms, carpeted bedrooms or recording studios.
Typically, in schools a shorter reverberation time is desirable. In rooms for pupils with hearing and communication needs this is essential. And, in spatial terms, a lower floor to soffit height is beneficial, although this might conflict with other design requirements such as a higher soffit for a service zone or the use of stack/cross ventilation.
The normal location for the bulk of the sound absorption and the most effective is on the ceiling and is often in the form of a lay-in grid, although this may not always match the architectural design or the need to expose the soffit for thermal mass. Alternative solutions such as suspended rafts or baffles, or perforated boards, are also feasible but may not provide sufficient sound absorption. Where additional sound absorption is required, this will often be in the form of wall panels, best positioned opposite the teaching wall to reduce lateral reflections.
Internal noise levels will also depend on site location, of course, and exposure to external noise sources, says Oldaker: ‘Where there is a noise source such as a road, building orientation and position can reduce the impact on the façade and the ventilation design.’
He continues: ‘Where noise levels are excessive, an attenuated form of ventilation is likely to be required. This could be either a local NVHR/MVHR (Natural Ventilation with Heat Recovery/Mechanical Ventilation with Heat Recovery) system or a centralised ventilation system. Both bring design issues to resolve, principally noise from in-room plant for the former, and the potential to reduce sound insulation between rooms due to service routes for the latter. With lager windows required for daylighting, this can increase the sound insulation requirements for glazing.
Oldaker recommends early site assessment and noise monitoring at RIBA Stage 2 to guide location and orientation through noise modelling, and analysis of the site and predicted noise levels at the building façade. This can aid in reducing noise mitigation of the building design or, where this is not possible, guide the appropriate method of ventilation at a very early stage.
What are the lessons we can learn?
Internal sound insulation through the specification of walls and floors can avoid disturbance from surrounding spaces but does not amount to ‘sound proofing’. Consideration of room adjacencies can provide better results and a more cost-efficient design due to thinner wall build-ups.
A number of issues arise with modern methods of construction, principally the gathering of suitable data on which to base the design because acoustic tests have not yet caught up with developing designs, Oldaker warns. Gaining an understanding of what is what is not available at an early stage will help ensure that this can be addressed to avoid impact on design and programme.
All of the above relates to acoustics in schools, but this sector has arguably educated more designers than any other in the importance of making acoustics part of a holistic design approach and ensuring that acoustic design advice is considered at an early stage.
The main lesson, Oldaker suggests, is that it is much easier to incorporate acoustics into the design than to try to add it later on. In addition to the costs associated with retrofitting, poor acoustics could mean the difference between an accessible and non-accessible education for many children and young people.
Thanks to Helen Taylor, Director, Scott Brownrigg; Daniel Oldaker, Director, Acoustic Consultants Ltd.
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