October 3, 2019
by Michael McCoy
The recent prevalence of open offices, including address-free workstations and collaboration spaces, is a response to the need to accommodate an increasingly transient workforce. These wide-open spaces are typically designed to create more dynamic interactions among employees at all levels of an organization.
However, in recent years the elimination of walls and private offices combined with the continued use of hard surfaces such as concrete or wood floors, glass walls, and low-profile desks has led to the rise of new challenges related to confidentiality and acoustic comfort, resulting in an increase in the demand for acoustical solutions.
The American Society of Interior Designers (ASID) conducted a study in which 70 percent of workers reported they could be more productive in a less noisy environment (for more information, read “Productive Solutions: The Impact of Interior Design on the Bottom Line” by the American Society of Interior Designers [ASID]). Given that office workers spend approximately two-thirds of their time doing quiet work, addressing noise and reverberation issues is necessary to maximize employee productivity. The World Green Building Council (WGBC) estimates more than 90 percent of an organization’s operating costs are linked to employee efficiency. Research suggests when efficiency and productivity drop, operating costs are likely to increase.
Aside from productivity increase concerns, designing for the tech-savvy and highly engaged individuals constituting Generation Z can be a driving force for talent retention. As employers seek new ways to create more appealing and productive spaces that enable employee interaction, they also need to consider the privacy needs and acoustical comfort of the occupants.
Historically, designing for acoustic comfort meant installing acoustical ceiling tiles or wall panels, occasionally at the expense of aesthetics or other essential elements such as light levels. Today’s innovative materials are delivering flexible solutions addressing more than sound management and reducing echoes and reverberation issues, while enhancing other aspects of the interiors, such as lighting and aesthetics. To design acoustically optimized spaces and to select code-compliant materials, it is vital to understand the fundamental principles of sound control and to be aware of the organizations and the standards governing noise-mitigation strategies.
Basics of sound management
Three things can happen to sound as it moves through a space or medium: it can be reflected, transmitted, or absorbed. To design for acoustic comfort, it is essential to understand the ABCs of sound management where A stands for absorbing, B for blocking, and C is for covering up. Each of those strategies serves a different purpose, contributing to acoustical comfort.
Materials serving as absorbers help reduce reflective sounds such as human voices, thereby decreasing reverberation time (RT) in a space. A material’s ability to absorb sound is measured by a noise reduction coefficient (NRC) or sound absorption average (SAA). In general, the higher the NRC or SAA, the better the sound absorption.
Noise barriers are used to block sound. In commercial offices, commonly used sound blockers are privacy dividers that help to reduce the impact of distraction from other people’s voices. Sound blockers can also be employed to reduce exterior noise (e.g. traffic or nature) or sounds originating from other floors, offices, or HVAC systems. Sound blocking is measured by sound transmission class (STC).
Sound masking helps maintain speech confidentiality and masks distracting noises, turning intelligible, distracting speech into unintelligible, non-distracting background noise. It is typically achieved with the use of ambient sound pumped through speakers.
Each principle has an intended purpose and should be used to optimize the acoustics of a space based on pre-determined parameters. This article focuses on sound absorption materials used to reduce RT.
Standards driving human comfort
Noise affects occupants in different types of environments in varied ways, but ultimately has negative impacts including productivity loss, lack of focus, and even memory retention. While applications such as concert halls and sound rooms have specific acoustic requirements, most spaces, including commercial offices, schools, and hospitality environments have few strong requirements around RT. However, sound level is an important consideration in all room types when looking to create more human-centric environments and improving occupants’ health and well-being.
Global building certifications such as the WELL Building Standard (WELL) and the Leadership in Energy and Environmental Design (LEED) are also increasing the awareness of the importance of human health and well-being in commercial environments. These organizations make recommendations on how to measure and achieve optimal RT, based on the type and size of space and how it is used.
WELL provides arguments supporting the use of acoustic optimization strategies in a built environment to bolster occupant health and well-being. The increased awareness of the importance of acoustic comfort is evidenced through the creation of a specific sound concept in WELL v2 (Feature S04). It contains two parts related to sound absorption. Part 1 relates to meeting the thresholds for RT, making recommendations based on room type and size (Figure 1). Part 2 pertains to implementing sound reducing ceiling solutions, specifically addressing NRC, a measurement of the amount of sound absorbed onto a surface, and ceiling coverage area.
Two of the rating systems under LEED v4, Building Design and Construction (BD+C) and Interior Design and Construction (ID+C), include requirements and credits related to acoustics.
The minimum acoustic performance prerequisite applies to schools under LEED BD+C and addresses HVAC background noise, exterior sounds, and RT. For the latter, it recommends the use of materials with an NRC of 0.7 or higher for a total surface equal to or greater than the total surface area of the ceiling, or that spaces meet the recommended RTs.
The Acoustic Performance Credit under LEED BD+C and ID+C addresses HVAC background noise, RT, and sound transmission, reinforcement, and masking systems. Specific RT requirements are listed for various room types and applications.
These standards have begun to propell change in commercial building design to promote well-being and create more comfortable environments. As manufacturers continue to introduce new products supporting the trend toward healthier workplaces, specifiers must familiarize themselves with the latest innovations and how to use these tools to design interior spaces to maximize occupant comfort.
Strategies for acoustic comfort
Designers have commonly optimized noisy environments with acoustic ceiling tiles (ACTs) or wall panels, often at the detriment of aesthetics. Commercial furniture manufacturers introduced low-profile desks, adding to the reverberation issues in open structures. They also commercialized phone booths and sitting nooks made of acoustical materials to help combat the additional noise problems.
While supportive of employee privacy needs when making phone calls or working as a team, these products alone do not contribute to improving the acoustics of a space. Recently, some architectural luminaire manufacturers have introduced integrated acoustic lighting systems to address acoustics needs as well as illumination requirements.
These flexible systems leverage the ceiling plane and often integrate existing building components such as sprinklers or speakers to simplify the specification, sourcing, and installation process. They are typically available in a variety of form factors—linear baffles and cloud systems are the most prevalent. Resolving more than reverberation issues, these systems can deliver optimal light levels and enhance the aesthetics of a space while offering flexibility to meet its budget requirements.
Specifiers have a variety of acoustical treatment options to select from. Therefore, when using the ceiling plane to design for acoustic comfort, it is necessary to first consider the goal of the space and go beyond sound management. Before selecting an acoustic ceiling solution, variables such as design aesthetics, budget, and the incorporation of other building components should be considered.
For applications where it is desirable to hide the open ceiling structure, ACTs or a dense array of an integrated acoustical lighting system (i.e. an illuminated and unlit acoustic baffle used together in a linear or architectural pattern) is suitable. If the intention is to maintain a view to the open ceiling structure or to reduce the budget, the same integrated acoustic lighting system can be optimized using fewer baffles. By varying the height, spacing, orientation, and product type—baffles or clouds, for instance—it is possible to achieve the desired vision and acoustic comfort within the constraints of a budget.
Collaborating for results
Acoustics are becoming a prerequisite when designing open ceiling environments, requiring greater collaboration between architects and acousticians. An integrated acoustic and lighting system offers many advantages from cohesive aesthetics to specification and sourcing ease, not to mention the piece of mind that comes with dealing with one supplier to design and manufacture a unified system with the ability to meet tight tolerances.
Once the acoustic requirements of the space have been established with the help of the acoustician, the architect and the team responsible for specifying building components such as the ceiling should consult with a lighting designer to ensure the selected acoustic ceiling solution meets the lighting requirements of the space. Often, during the design phase, specifiers and consultants work in isolation, leaving the opportunity for a specification to be altered during the bidding process.
As new hybrid products emerge, it becomes imperative specifiers work together with acousticians and other specialists to familiarize themselves with the requirements of the space, such as sound management and illumination levels, especially if the client is striving to meet a global building certification.
For example, an acoustic luminaire and baffle system can cross divisions and sections of a specification. These systems may be listed under both Divisions 9 (Ceilings) and 26 (Electrical) of MasterFormat. To guarantee the acoustic, lighting, aesthetic, and budget needs of a project are met, eliminating communication barriers and building a more collaborative process can create a tighter specification and safeguard the overall design.
Additionally, installers should be included earlier in the process. These integrated systems involve both the electrical and ceiling installers. Therefore, upfront coordination can go a long way toward ensuring a hassel-free process during the construction phase. Streamlining the design-to-installation process is becoming necessary as innovative products and new technologies emerge.
A design trend toward creating more human-centric environments is growing in importance in commercial building design, supported by global building certifications and standards, and the introduction of new products.
A significant and rising requirement for workforce comfort, happiness, and productivity is sound management, especially in open, multifunctional interior spaces. As a new generation that prioritizes human experience enters the workforce, now is the time to pay greater attention to considerations related to human health and well-being by seeking new opportunities, materials, and processes.
Michael McCoy leads the new ventures team at Focal Point, delivering new value to the architecture and design community through innovative products and services. He has spent the past 15 years commercializing novel technologies across a range of industries. He can be reached at email@example.com.
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