white paper
sound conditioning:
the key to successful office fit-out
This white paper investigates how the early inclusion of sound conditioning technology in office design can save cost, streamline the fit-out process and create an acoustically controlled workplace for optimal productivity, speech privacy, acoustic comfort. Furthermore, the resulting fit-out will be acoustically controllable to adapt to any reconfiguration of the space and it’s use.
introduction
As offices change to accommodate the impacts of COVID and post-COVID working practices, control, flexibility and reduced cost will play an increasingly important role in office design as companies change the way they work and how many staff they need to accommodate and any time.
Traditional fit-out design and interior construction methods are quickly becoming outdated as working practices become more fluid in location and style.
In this white paper we have worked with several acoustic consultancies to investigate how acoustics can play a crucial role in changing the old fixed interior construction methods to acoustically optimised, truly flexible, reconfigurable workspace at lower cost.
why do offices fail?
Office use and design are always changing.
Having evolved from predominantly cellular space through open-plan to the latest activity-based working environments, they still often fail to live up to expectations of productivity, privacy and comfort.
Unlike more social spaces like restaurants, café and bars where the occupants are all doing the same thing, office space design has a unique challenge in having to accommodate workers who perform the two audibly opposing behaviours of collaboration and concentration.
This challenge has, and still is the undoing of even the most creative workplace designs. Attempting to segregate workers by physical means to separate these behaviours like building partitions and using furniture and other interior design strategies are effective, but only to an extent.
The reason these strategies often still fail is an acoustics issue, or to be more precise an issue of ambient sound level.
what is ambient sound?
Ambient or background sound is the constant sound in a given space which is there 100% of the time yet is usually unnoticed. In a modern office this would usually consist of a combination of the noise from air conditioning, plant or external traffic noise penetrating the façade of the building.
It plays a crucial role in the overall effectiveness of a workplace because it directly impacts the intelligibility of speech and clarity of other distracting sounds.
It impacts on productivity because it directly affects our ability to concentrate for extended periods and impacts on privacy as it effects how much people hear either between rooms or across open-plan space.
When ambient sound level decreases, speech intelligibility increases, and every spoken word is clearly heard and understood. Conversely, when ambient sound level increases intelligibility of conversation is reduced and becomes more private.
Consider these 2 examples: in a silent library when someone speaks, their words are either easily overheard or if further away are, at least, a rude interruption against an otherwise quiet background. Alternatively, in a noisy café or bar, even conversations at close range are not easily heard or overheard.
Of course, these are more extreme examples to demonstrate how ambient sound works but, in an office environment a more subtle version of this is at play.
Unlike the café or bar where patrons are all doing the same thing, an office has to address the fundamental challenge that workers need to collaborate at one time in one place while others need to concentrate on individual tasks nearby.
The performance of both cellular and open office space is greatly affected by ambient sound level but in Australia conventional acoustic design has relied on existing sources of ambient sound such as air conditioning to provide this important component of the acoustic mix.
Back in the day, unsophisticated, noisy air conditioning, plant or external traffic sound generally provided too much ambient sound, but now things are very different. Modern AC systems and façade construction are much more sophisticated and thankfully much quieter but consequentially in most cases can no longer be relied upon to provide ambient sound at the correct volume and spectrum delivered uniformly across the workplace.
from room to room
Workmanship will vary from project to project, but ambient sound level should not be an uncontrollable variable, in fact it should be precise and controlled to varying levels throughout the space.
Traditionally, drywall is constructed in conjunction with the ceiling to prevent conversation being overheard between adjacent rooms and adjacent open-plan office space. Each room is given a nominated privacy factor relevant to the level of confidentiality required therein.
To achieve each privacy factor, a different construction method is used which might vary from a single sheet of plasterboard on either side of an uninsulated stud constructed from the floor to the underside of a suspended ceiling (approximately Rw30), providing a low level of privacy at low cost. Alternatively, a double sheet of plasterboard either side of an insulated cavity, constructed from the floor through the suspended ceiling to the concrete slab above (approximately Rw50) which would provide a higher level of privacy at higher cost.
Although this makes perfect sense on the face of it, there is another element to the acoustic privacy which is less tangible and if not controlled often leads to the failure, not only, to the expected privacy performance of adjacent rooms but to entire fit outs.
This element is ambient sound
The cost to the eventual occupant of the space is not only the dollar value and inconvenience to correct the failure, but also the loss of confidentiality.
Using new acoustic design techniques, it is possible to not only prevent these issues from arising in the first place but create a more cost effective and more flexible fit-out in the first place which can easily and inexpensively adapt the needs of the business post occupancy.
Without getting bogged down in the detail of wall construction, the main reason why the expected speech privacy performance is not met is down to the quality of workmanship and the insufficient level of ambient sound in the space. If either, or both, of these elements are lacking, the partition will fail to deliver the privacy level specified.
Although workmanship will vary from project to project, ambient sound level should not be a variable, in fact it should be precise and controlled.
In these circumstances, it can not only make up any shortfall in performance due to poor workmanship and meet the privacy levels required, but it can also enhance productivity, speech privacy, comfort and flexibility of the entire fit-out.
slab to slab vs floor to ceiling
Being able to manage ambient sound effectively provides precise control over room privacy without the need to over-engineer unnecessarily.
The diagram below shows the relationship between the as-built onsite rating of a partition separating rooms (Dw), the ambient sound and the resulting privacy factor.
It shows how a wall successfully built to a nominated Rw rating will underperform and even fail to achieve the expected privacy factor if the ambient sound level is lower than expected.
A drywall designed and built to achieve a minimal FAIR privacy factor of 70 using a floor to suspended ceiling construction will fail if the ambient sound level in that space falls below 35 dBA. The chances of this happening when relying on traditional sources of ambient sound is very high.
However, when ambient sound is controllable and ‘locked-in’ at the correct level as recommended in the Australian Standard (AS2107), a drywall can be constructed to a lower performance but still achieve the desired privacy factor importantly often without having to build slab to slab.
in the open
open-plan, activity based working
In open office space meetings occur at random as workers collaborate throughout the day.. As this is also the location where staff will attempt to concentrate on individual tasks the fundamental challenge between concentration and collaboration emerges.
Attempting to encourage these different behaviours using furniture and interior design is difficult if the acoustics are not properly managed. Like the library example earlier, if an open-plan space is deficient in ambient sound, speech will be heard in adjacent areas loud and clear. When it is controlled and set to the correct level, privacy is increased over distance. Local team conversation is heard as normal, but other conversations further away merge into the background sound. Interruption is decreased across the space and those in quiet focus can concentrate for longer periods without having to miss out completely on their team communication as they do working remotely.
collaboration vs concentration
This diagram shows how intelligibility of speech from a source changes as ambient sound is optimised.
When ambient sound is low, the large area (green) shows the extent of the distraction by the speaker (blue). As the ambient sound is optimised the new smaller extent of distraction is shown (red)
By optimising ambient sound workers are distracted less by other conversations and remain focused for longer increasing productivity.
the new way
sound conditioning
Rather than hoping to achieve a reasonable level of ambient sound from existing, uncontrollable sources, artificial ambient sound generation using sound conditioning technology delivers a precise and controllable sound which creates an acoustic ‘foundation’ onto which partitioning can be constructed and open-plan space managed.
Sound conditioning is a technology that creates ambient sound artificially through a network of loudspeakers usually placed out of sight above a suspended ceiling. Although it’s been around since the 1950’s also known as white noise or sound masking it has only recently caught on in Australia as an integral part of a few notable installations including Barangaroo International Towers, Suncorp’s 10 Shelley Street and Westpac’s 275 Kent Street in commercial office and two of ANU’s new buildings in Canberra and Monash University’s Learning and Teaching Building
The use of sound conditioning in these projects has provided, not only an acoustic foundation onto which the current fitouts were constructed, but essential control to cater for any subsequent reconfiguration of the spaces.
Rather than solely relying on heavily designed partitions, simpler, more cost-efficient partitions with lower acoustic performance can be combined with a sound conditioning system to achieve the required privacy performance. For most cellular space this means the difference between building partitions from slab to slab and from floor to ceiling. In buildings with many rooms this can mean savings in the hundreds of thousands of dollars as was achieved at ANU in Canberra on two of their latest flagship projects.
A reduced partition rating requirement also means that highly flexible, moveable proprietary architectural wall systems can be used where previously the use of these in
traditional, uncontrolled acoustic environments would be considered, high risk. Post-occupancy, workspace can keep up with the ever-changing requirements that business has of its space. Reconfiguration of flexible systems is as easy as moving the walls (often over weekends preventing any downtime, mess and inconvenience) and re-tuning the sound conditioning system (usually as simple as a click of a mouse) to create the privacy level required.
Open-plan, activity-based working workspace is optimised as speech intelligibility is decreased. This means that collaboration between workers at close quarters is much less distracting to those not involved seated further away. Open office environments really start to work as intended. Decreased interruption and distraction leading to increased productivity and acoustic comfort. In overly quiet workspace, workers are inhibited as they instinctively know that their colleagues can hear every word. Constantly retreating to closed offices for normal business conversations with team members or clients over the phone is costly to productivity and flow. Feeling free to talk to colleagues and customers anywhere at any time is liberating and gets work done.
Supplementary soundscaping is also an easy addition to these systems. Environmental sounds can enhance a particular location in the office encouraging relevant worker behaviour. For example, breakout or relaxation space defined by sofas or easy chairs are further enhanced with music or sounds from nature. Communal collaborative space such as café and dining zones greatly benefit from music or even the subtle background sound from a real café!
Summary
Sound conditioning has, up until recently, been considered a last resort to fix unforeseen issues. Thanks to the improvements in the technology and accurate calibration of these systems it is now being proactively designed into projects to manage acoustics accurately to provide construction savings.
Sound conditioning not only provides a great degree of acoustic control over the designed fit-out, but it also gives ongoing control for subsequent reconfigurations optimising each design for productivity, privacy and comfort going forward.
Office use and design are quickly changing to serve a new work-life and getting the most out of a smaller space will make even greater demands on fit-out to provide for flexibility, privacy and productivity.
Although acoustics has always played an important role in office design, now more than ever is the time to embrace new technology to enhance performance.