acoustical comfort in healthy buildings & interiors
acoustical comfort / acoustics in interior design / healthy buildings / wellness interiors / sound mapping / acoustic materials / acoustic finishes / well building standard
What is acoustical comfort?
When due attention is given to interior acoustics as part of the design and fit-out process, unwanted sound simply should not be an issue for building occupants, meaning there are no distracting echos or noise levels beyond those that align with the primary activity taking place in that area - this can differ greatly between a buzzy restaurant for example, and a library or office.
Due to the subtleties of this zone by zone approach, ‘acoustic comfort’ is a largely qualitative concept evaluated primarily by occupant satisfaction surveys - using questions such as “is the sound level right for what you are doing?” and so on.
We also have the possible addition of quantitative data via more scientific measurements around decibel levels and a lot of planning takes place in advance of a refurbishment or fit-out to anticipate potential acoustical comfort issues before they become reality.
As we explore below, a wellness interior designer has a number of tools at his or her disposal to integrate materials that absorb sound into the space, no matter whether it be office, residential, retail or restaurant.
What are the main causes of poor acoustics in buildings and interiors?
Building issues such as loud HVAC equipment, improperly insulated spaces, or an excess of hard interior surfaces in areas with regularly high densities of occupants (and their conversations), can all contribute to poor acoustics and occupant discomfort.
Airborne noise such as the air con / HVAC system and other mechanical appliances is all too common, especially in older buildings. Then there are of course the sounds of other occupants in or outside a building, primarily via speech but also footfall, opening or closing doors and so on, all of which can cumulatively become a recurring distraction and reduce concentration.
Impact noise, for example from a gym or children playing, is an even more acute version of the same problem. Imagine operating a spa or retail space on the ground floor of a building with a first floor CrossFit gym above (without proper sound insulating flooring to absorb the sound of loaded barbells being repeatedly dropped).
Then there is the problem of a lack of acoustical privacy between enclosed spaces and equally within open-plan spaces, with noise traveling from one of the space to another, bouncing around from wall to wall constantly.
Finally, there is the external noise source of passing transportation such as cars, buses, trains or planes, which can become intensely distracting both during the work day and at night.
What are the health risks of interiors with poor acoustics?
Human exposure to unfavorable noises and improperly regulated acoustics has a tangible impact on mental wellbeing, concentration and focus. It’s not going to send you to an early grave perhaps but it can create a consistent, low-level anxiety and stress that accumulates over time.
In other words, in the world of healthy buildings and wellbeing interiors, as consultants and advisors, we want to implement a strategy upfront in order to minimize acoustic discomfort, likely in collaboration with the Mechanical Engineer and Architects for new build construction or refurbishment projects, or solo as wellness interior designers if it’s an interior fit-out.
Consider how a lack of acoustical privacy, speech intelligibility, and general distractions can all impact our comfort in an open-plan office space for example - whether the noise source is from inside that workplace, elsewhere on the same floor or outside the building.
Typical mental wellbeing issues we encounter in such situations are a reduction in attention span, memory retention, and (in a residential context) lower quality sleep at night.
Designing with good acoustics in mind is therefore a fundamental part of any healthy building concept and wellbeing interior design strategy, so let’s look at the tools available to us.
How can a wellbeing interior design consultant improve an acoustics issue?
To combat these issues, strategies such as planned and isolated HVAC systems, reinforced facades, plenty of sound absorptive materials in the interior specifications and the introduction of consistent background noise / white noise can all be useful.
A range of solutions we might choose to deploy as part of a wellness interior design consultancy assignment would include the following:
Planning of isolated/balanced HVAC mechanical equipment sound levels (provides baseline/anticipated noise levels) in line with WELL recommendations of between 25 maximum noise criteria (NC) for enclosed offices and 40 maximum noise criteria for open-plan office spaces (Ref. WELL Building Standard)
Fortification of facades (affects exterior noise intrusion) but will require engineers and architects involvement (more suitable for full refurbishment projects rather than interiors only)
Replacing hard surfaces with sound reducing, sound absorbing surfaces, wall panels, ceiling baffles and surface finishes (ref. Noise Reduction Coefficient - NRC - an average value reflecting its acoustical sound absorbing properties - see WELL Building Standard for more)
Introducing consistent background noise levels (sound masking) for added acoustic privacy
Using non-hollow core door ways with gaskets or sweeps to block noise traveling from one side of a door way to the other
Interior partition walls with high acoustic absorption qualities, e.g. Sound Transmission Class (STC) of minimum 45 (ref WELL Building Standard)
Interior walls designed for acoustic performance with minimal air gaps and sound transmission, ‘vertical surfaces in an open workspace should have a minimum NRC of 0.8 on at least 25% of the surface area of the surrounding walls' (ref. WELL Building Standard)
Exterior windows with high acoustic absorption qualities, e.g. a Sound Transmission Class (STC) of minimum 35 (ref WELL Building Standard)
Imposing limits on music played in a space to limit distractions, e.g. “7 decibels (dBA) above the ambient sound pressure level when measured at a minimum distance of 4.5 m [15 ft] outside of the entrance to the space” (ref. WELL Building Standard)
Ceiling surfaces should have a minimum NRC of 0.9 for the entire surface area of the ceiling (excluding lights, skylights, diffusers, beams, joists and grilles) (ref. WELL Building Standard)
What does the WELL Building Standard advise on sound and acoustics?
The WELL Building Standard / Sound section aims to confront potential acoustic problems and provides various strategies to diminish negative health impacts. While it is up to the architects and wellness interior design consultants to interpret these objectives creatively through the lens of design, aligning their decisions with the desired wellbeing outcomes. In this way, health can and should become a central part of the design process from the very start of a healthy building design project.
WELL Building Standard SOUND / S01: Sound Mapping
Goal: create site zoning/acoustical plan that identifies potential noise sources that could affect a specific space. This equates to designating ‘loud’, ‘quiet’, and ‘mixed’ spaces according to zone or the programming of each space making up the floor plan or ‘sound map’.
So for example, within an office floor plate, we would create area for ‘deep work’ and solo concentration, as well as more collaborative areas for small groups and private meetings rooms, perhaps integrate some Skype cubicles for 1-2 people while on a call, and so on.
WELL Building Standard SOUND / S02: Max Noise Levels
Goal: Establish background noise levels for interior spaces to determine HVAC and façade design techniques in order to avoid speech intelligibility problems.
WELL Building Standard SOUND / S03: Sound Barriers
Goal: Increase speech privacy, highlight design constraints that may hinder acoustical comfort while including sound absorbing partitions (especially in open floor plans) as physical privacy is often mentally linked to acoustic privacy.
WELL Building Standard SOUND / S04: Sound Absorption
Goal: Design spaces that support speech intelligibility and increase focus paying particular attention to the hazards of hard surfaces that have the potential to reflect more sound and cause acoustic discomfort. By using sound insulating materials interior designers can control the sound absorption levels in any given space, for example via acoustic ceiling panels, flooring and/or wall panels, where appropriate.
WELL Building Standard SOUND / S05: Sound Masking
Goal: Increase acoustical privacy through noise suppression, where sound masking involves deliberately layering in an even noise level, for example of ‘white noise’ or nature sounds.
WELL Building Standard SOUND / S06: Impact Noise Management
Goal: Manage background noise levels between building floors, conscious that lightweight floor construction (CLT, wood truss, steel frame) emits more noise than resilient floor-ceiling construction (thick concrete slab, suspended ceiling).