Below is my contribution to the August 2021 issue of tED Magazine, the official publication of the NAED. Reprinted with permission.
Nearby, co-workers are talking. A phone rings. A printer busily churns out paper. Somebody walks past. Another co-worker laughs at a joke.
In the COVID era, many people missed the social aspects of working in an office but probably not the noise and distraction. When trying to concentrate, noise not only produces stress and irritation but can impair productivity.
According to a Center for the Built Environment post-occupancy evaluation of 142 buildings involving more than 23,000 respondents, office workers are most dissatisfied with noise from nearby conversations and lack of sound privacy; more than half believe acoustics interfere with their ability to get their job done.
As such, acoustic comfort is an important consideration in interior design. Building design rating systems such as Leadership in Energy & Environmental Design (LEED), WELL, and Collaborative for High-Performance Schools (CHPS) now address it. Acoustic comfort’s importance is only growing as the last decade produced an open office trend, with a majority of office space having low or no partitions. Further, an aesthetic trend toward open ceilings has become more popular, resulting in traditional acoustic ceilings disappearing.
Building owners and managers have a number of options to address acoustic comfort, from vinyl or cork flooring to noise-reducing shades or soundproof blinds to sound-absorbing panels. Lighting manufacturers developed their own solution: acoustic luminaires.
These luminaires produce general illumination while incorporating some type of sound-absorbing material into their design to reduce environmental noise. While they are not a panacea, typically impose a cost premium, and require know-how for evaluation and application, they can serve as an effective contributor to a building’s acoustic comfort strategy.
“Over the past several years, there has been a dramatic increase in market demand for sound-absorbing luminaires,” said Michael McCoy, Director, Architectural Systems, Focal Point. “Acoustical lighting was considered a niche market where only small players were active but is now in the early stages of growth, with many major lighting manufacturers trying to find their place.”
Image courtesy of Focal Point.
Acoustic luminaires
Similar to light rays, sound can be reflected, transmitted, and absorbed. Acoustic management therefore uses an “ABC” approach to reduce noise: absorb, block, or cover up. For absorption, the foremost goal is to reduce reverberation time, or the continuation of sound after the source of the sound has stopped.
Acoustic luminaires incorporate various soft and/or porous materials that absorb sound. While foam or natural materials such as wool may be used, typically felt is either attached as panels, serves as the luminaire housing or shade, or wraps around the luminaire frame. Available in multiple colors, felt readily coordinates with specialty felt acoustic ceilings, which may be available from the same manufacturer, and can otherwise offer a highly distinctive aesthetic and support the desired space appearance.
Sound absorption depends not only on the material but its thickness and surface area. Additionally, the luminaire may feature attributes such a lack of interior aluminum, which allows any sound that is not absorbed to pass through an open-air gap to the other side, where it is likely absorbed.
“The beauty of putting sound-absorbing features into lighting fixtures is they are at once out of the line of sight and still can provide effective acoustic control,” said Dirk Zylstra, VP Design, Acuity Brands – Architectural Specialty. “Fixtures close to ceiling surfaces can multiply the effect of capturing sound by absorbing not only direct but also reflected and refracted sound waves.”
Open offices are naturally a major application for this product, though it is applicable anywhere acoustic comfort is important: schools, meeting spaces, gymnasiums, studios, cafeterias, libraries, courtrooms, performance spaces, and others.
Image courtesy of Focal Point.
Evaluation and application
Acoustic luminaires could be regarded as lighting fixtures with an added feature. As such, they should first and foremost be evaluated based on their ability to perform their primary function of providing general illumination.
For the luminaire’s sound absorption effectiveness, a number of metrics are used. A common metric for two-dimensional surfaces like partitions and carpeting is Noise Reduction Coefficient (NRC). Because lighting can be three-dimensional, however, a different metric may be required: Sabins, which is a measure of sound absorption per square foot of material.
It starts with reverberation time (RT60), which is the amount of time it takes for a sound to decay by 60 decibels. (Both LEED and WELL focus on reducing RT60 to a desired level based on application.) RT60 is independently tested and used to calculate Sabins, with the resulting information published in an ASTM C423 report.
The report is then used to optimize acoustic comfort in a given space. (As such, distributors should expect the manufacturer to produce it.) Application can be challenging, as luminaire quantity, mounting height, and spacing can have a big impact on sound-absorbing properties. Again, the distributor should expect the manufacturer to provide layout and calculation support, and they should ensure any substitutions provide the same performance.
“As we can see, this is not a simple endeavor, so the distributor should rely on the manufacturer or an acoustician to provide support to validate the effectiveness of the product in the space,” McCoy said.
After lighting and acoustic performance, aesthetics will be a significant factor in evaluating solutions, so application may require some coordination with the designer to approve the acoustic material and ensure proper color matching. Because of color matching and other aesthetic considerations, it may be advisable to avoid mixing manufacturers, at least in the same space.
“Given their acoustic impact and differentiated aesthetic, distributors may need to reach further upstream in the interior architectural design process,” McCoy added. “Developing relationships with key decision makers including architects, interior designers, acousticians, and ceiling contractors—and acquiring a basis of knowledge around acoustic materials and sound management—will help distributors gain a stronger market presence and help hold projects downstream.”
Image courtesy of Focal Point.
Final word
“Acoustic fixtures are a great opportunity to differentiate from the crowd, and early adoption and understanding can put the distributor in a position of leadership and expertise,” Zylstra said. “A little like LED in the early days, this is a trend that is here to stay, and wellness and human health are even more in focus following the pandemic.”
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