Acoustic ceilings to support occupants’ health

September 1, 2021

By Diana Hart, CSI, IIDA

Photo by Robert Pepple, Pepple Photography/courtesy of Rockfon

While specification and design professionals have long considered the effects of material and product choices on the people within the spaces and buildings they create, the COVID-19 pandemic has underscored the importance of designing healthy spaces. With a greater understanding of indoor environmental quality, acoustic ceiling material choices, and relevant product certifications, specifiers can have a positive impact on buildings’ indoor air quality (IAQ), lighting, safety, acoustic comfort, and, ultimately, on people’s health and well-being.

IEQ and influential standards

Acoustic ceiling product selection and specification impact four key elements of Indoor Environmental Quality (IEQ):

• acoustics;

• IAQ;

• lighting (including daylighting); and

• fire protection.

Green building standards and certification programs help amplify the message of IEQ’s effect on occupant health and well-being. Two of the most influential standards are the U.S. Green Building Council’s LEED v4.1 and the International WELL Building Institute’s WELL v2.

• LEED v4.1’s[2] EQ credit category recognizes the benefits of low-emitting materials including Underwriters Laboratories Inc. (UL) GreenGuard Gold-certified products, as well as the benefits associated with acoustic performance and interior lighting.

• WELL v2 Pilot’s[3] “10 Concepts” approach addresses IEQ in Air, Light, Thermal Comfort, Sound, and Materials concepts.

In addition, the International Living Future Institute (ILFI) is gaining awareness and adoption for its Living Building Challenge 4.0[4] program’s seven performance ‘Petals’ and 20 ‘Imperatives.’ Healthy Interior Environment and Health Interior Performance are two of the imperatives. Living Building Challenge certification is based on 12 months of actual data of the operational, occupied space.

High sound absorption, low reverberation

Acoustic comfort is an essential IEQ element necessary to create comfortable, functional rooms for speech, focus, activity, music, and more. Interior ceiling systems with sound-absorbing materials play a significant role in providing a good acoustic experience. Selecting and specifying acoustic ceiling panels with a high noise reduction coefficient (NRC), typically an NRC 0.90 or higher, will provide the necessary sound absorption.

The acoustic ceiling tile NRC rating refers to how much sound the ceiling material can reduce noise by absorbing sound. A higher number indicates more absorption. NRC generally varies between 0 (no absorption) and 1 (very high absorption) and is the average of the sound absorption coefficients at four frequency ranges, the 250, 500, 1000 and 2000 hertz (Hz) octave bands. Ceiling noise reduction is measured according to ASTM C423, Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method. Using higher NRC ratings also can reduce cost because fewer sound-absorbing products need to be installed to reach the goal amount of absorption in the room.

Nelson Architects designed the interior of Anthem Technology Center’s new LEED Silver-certified, 21-story, Class A, build-to-suit office tower in Midtown, Atlanta, to include acoustic stone wool ceiling products that deliver a high NRC of 0.95 and reflect up to 85 percent of light. Photos by Brandon Stengel, Farm Kid Studios Inc. courtesy Rockfon

Ceiling panels with a high NRC offer numerous benefits to occupants. A good acoustic experience does more than ensure more people are heard and understood. Unwanted and unclear sounds interfere with communicating, concentrating, sleeping, and other daily tasks. Noise has both physiological and psychological impacts. Short-term, it activates the ‘flight or fight’ stress response that raises blood pressure, increases heart rate and respiration, and often leads to irritability and distraction. Sustained exposure to disruptive noise can lead to lasting, long-term health effects and hearing loss.

In offices, excess noise results in a drop in performance and impaired concentration. The U.S. General Services Administration’s Public Buildings Service (PBS)[6] manages 34.4 million m2 (370 million sf) of space. With a mission to deliver “superior workplace at superior value for the U.S. taxpayer,” PBS found every distraction takes a person approximately 15 minutes to return to a focused task, resulting in a high cost of wasted time and productivity due to poor acoustics. Among its solutions, PBS recommends, “Specify ceilings having a minimum NRC of 0.90 in open plan offices.”

In classrooms, acoustics can determine whether students are heard when asking questions, comprehend their lessons, act out from frustration, and can focus when taking tests. In many classrooms[7], listeners with normal hearing can only understand 75 percent of the words spoken.

In schools with poor acoustics, teachers and staff must strain to be heard. They become less effective and less satisfied in their work. Their stress increases and their health suffer. In fact, one survey[8] reported 20 percent of teachers missed work due to voice problems.

In healthcare facilities, acoustics and quiet promote rest and recovery for patients. A good acoustic experience also helps lower stress for staff and visitors, reduces medical errors with improved accuracy, and provides the necessary privacy to protect patient confidentiality. Acoustic requirements are outlined in several healthcare facility standards, including the Facility Guidelines Institute’s (FGI’s) Guidelines for Design and Construction of Hospitals, the Health Insurance Portability and Accountability Act (HIPPA), LEED, and WELL.

LEED v4.1 offers acoustic credits in three categories and WELL v2 includes ‘sound’ as one of its 10 ‘concepts’ with eight corresponding ‘features.’ Using a three-step approach to optimized acoustics supports these programs’ criteria and creates spaces that support people’s comfort, health, and well-being.

  1. Selecting the appropriate NRC rating for ceiling panels, absorbing sound, and controlling reverberation and noise.
  2. Selecting the appropriate sound transmission class rating for wall and floor-to-ceiling assemblies, preventing noise transfer between rooms using full-height walls.
  3. Selecting the proper background sound levels, masking annoying or distracting noise.

IAQ goals and performance-based material selection

Denver-based law firm Greenberg Traurig worked with Gensler to design its new office with a contemporary look. To achieve this, white, light-reflective, stone wool ceiling panels were used for its 3-m (10-ft) high ceilings. Photo by Ryan Gobuty courtesy Gensler and Rockfon

When selecting and specifying ceiling systems to support IAQ goals, consider the material’s properties and performance.

For commercial interior ceiling systems, the most common material choices are often selected first for their appearance:

• Wood—warm, inviting, natural look with tactile qualities, enhanced with stains and coatings.

• Metal—modern, high-tech appeal in metallic tones, painted in a full spectrum color, or finished to mimic natural wood.

• Gypsum and plaster—smooth, monolithic, modern aesthetic; mostly in white.

• Fiberglass—slightly textured surface with yellow substrate; mostly in white.

• Wet-felted mineral fiber—fissured surface; mostly in white.

• Stone wool—smooth or lightly textured surface; mostly in white.

If appearance was the only consideration, most design professionals would prefer the smooth, white plaster ceilings. It is often impractical because it provides no access to the plenum above it, and it is highly sound reflective. Acoustic ceiling panels installed in a ceiling suspension system create a gridwork with access to the plenum.

Within the suspended ceiling system, design and specification professionals then weigh the panels’ aesthetic attributes against their four key IEQ elements and other performance requirements.

Light reflectance

White ceiling panels, especially those with smooth surfaces, have a high light reflectance. This means natural light from an exterior window can be reflected more deeply into a building’s interior. Maximizing daylight reduces the demand for electric lighting, which improves energy efficiency and lessens the associated costs and emissions for lighting and cooling the building.

Whether from natural or electric sources, the light reflected off the ceiling panel will be diffused. This helps reduce glare on monitors and screens. Glare can cause eye strain, headaches, and other stress-related issues. Diffused light aids in a more comfortable, productive environment that supports people’s well-being.

In most commercial settings, including those projects seeking LEED v4.1 certification, ceiling panels with a light reflectance of 0.85 or more is the preferred specification.

Flame and smoke spread

The National Fire Protection Association (NFPA)[10] notes “most fire deaths are not caused by burns, but by smoke inhalation.”

Two key measurements are used for interior ceiling products and assemblies in helping protecting people and properties by minimizing the effect of fire, smoke, and related hazards: flame spread index and smoke developed index.

The highest performance specification as required by the 2021 International Building Code (IBC), Section 803[11], is a Class A fire rating with a flame spread index of zero to 25 and a smoke developed index of less than 450. Materials with a Class A designation may ignite, but will not spread a flame and will not release excessive smoke that could obscure visibility during an emergency egress event.

Prioritizing performance

Selecting and specifying ceiling materials considers all four elements of good IEQ—acoustics, IAQ, lighting, fire protection—and more. As examples: fiberglass ceiling panels have an acceptable appearance, good sound absorption, and are lightweight, but if there was a fire, they would melt at a low temperature. Wet-felted mineral fiber panels’ acoustic fissures help with sound absorption, but are considered by most designers to have a dated, unattractive look, and need added chemicals to resist fire and mold.

Stone wool ceiling panels have a smooth non-fissured surface and provide high sound absorption. The panels are manufactured with natural basalt rock and recycled materials. Further, because it is made of stone, there is no need to add flame retardants or antimicrobials to achieve the desired performance. Stone wool withstands temperatures up to 1200 C (2200 F) and has a smoke developed index of 5. Similar to stone wool’s properties, metal also does not need additional chemicals to resist combustion or potentially harmful microorganisms.

Mold and moisture

Ceilings composed of organic fibers and water-based materials need to add a biocide, fungicide, or antimicrobial to help protect against the mold and mildew. With the added chemicals, these materials may become a potential pollutant source contributing to poor IAQ.

Keep in mind products that add antimicrobials are inhibiting the growth of microbes, such as mold spores. There is little evidence antimicrobial surface treatments prevent or reduce the spread of viruses or result in healthier populations. The disadvantages of using antimicrobials[12] can include increased resistance to antibiotics, a false sense of security, and increased costs.

Mold also has a cost. Left to propagate, mold can negatively affect people’s health, products’ performance, and appearance, and eventually, buildings’ structural integrity and long-term value. Mold thrives when a spore lands on a surface where organic food (such as fibers, starches, and cellulose) and moisture are present, and temperatures are 5 to 38 C (40 to 100 F). Mold can grow rapidly in as little as 24 hours.

Stone wool and metal are inherently mold-resistant materials, and easy to clean without harsh chemicals. They are not organic and, therefore, they do not provide sustenance to mold, mildew, bacteria, fungi, and other microorganisms. They also do not absorb water, moisture, or humidity.

Beyond mold mitigation, ceiling panels that resist moisture and humidity do not sag, warp, rot, or fall out because of water absorption. Hydrophobic materials like stone wool support good IAQ by alleviating concerns associated with supplemental natural ventilation from operable window systems, or when HVAC systems are turned off when the building is unoccupied. This moisture-resistant attribute also can assist during buildings’ construction schedules by allowing ceilings to be installed prior to the envelope being completely sealed or the HVAC system made operational.

VOCs and low-emitting products

MPI Media Group’s office in Orland Park, Illinois, uses acoustic stone wool ceiling panels to add dramatic visual contrast and optimal sound absorption to enhance its workplace experience and operations. Photo by James John Jetel Photography/courtesy Rockfon

Water, mold, viruses, and bacteria are all naturally occurring challenges. Volatile organic compounds (VOCs) are also released from many natural sources. These organic chemical compounds are used in thousands, possibly millions, of products.

According to the EPA[14], “Concentrations of many VOCs are consistently higher indoors (up to 10 times higher) than outdoors.” The health impacts of long-term exposure to high levels of VOCs may include:

• Eye, nose, and throat irritation;

• Headaches, loss of coordination, and nausea;

• Damage to liver, kidney, and central nervous system; and

• Cancer.

To reduce the risk of these health impacts and bioaccumulation on building occupants, design and specification professionals are selecting materials and products with the lowest level of VOC emissions. Two trusted resources are the UL Environment’s GreenGuard certification program, and the ILFI’s Declare Label 2.0 transparency platform and product database.

GreenGuard certification

“Products that have achieved GreenGuard certification are scientifically proven to meet some of the world’s most rigorous, third-party chemical emissions standards, helping to reduce indoor air pollution and the risk of chemical exposure, while aiding in the creation of healthier indoor environments.”

For next-level verification, products that earn the GreenGuard Gold Certification standard[15] also meet “health-based criteria for additional chemicals and requires lower total VOC emissions levels to help ensure products are acceptable for use in environments like schools and healthcare facilities. In addition to limiting emissions of more than 360 VOCs and total chemical emissions, GreenGuard Gold Certified products must also comply with requirements of the state of California’s Department of Public Health (CDPH) [Section 01350].”

Review the selected ceiling product’s GreenGuard Gold Certification to ensure it complies with the room application. Remember the larger the room, the greater its volume, which means there is more air to disperse chemical emissions. For example, the same emission levels will have a greater concentration and potentially greater affect in a small, enclosed office versus a large, spacious lecture hall.

Declare labels

Compliance with CDPH Section 01350 is also required for the ILFI’s Living Building Challenge 4.0 standard. Specifically, Imperative 10 requires all interior building products that have the potential to emit VOCs to demonstrate their compliance. Imperative 13 further requires manufacturers disclose the ingredients in their products to ensure they are free of Red List chemicals.

ILFI explains, “The Living Building Challenge (LBC) Red List represents the ‘worst in class’ materials, chemicals, and elements known to pose serious risks to human health and the greater ecosystem that are prevalent in the building products industry.” Included on the LBC Red List are VOCs in wet applied products, monomeric and polymeric flame retardants, and antimicrobials marketed with a health claim.

The Declare Label 2.0[16] by ILFI supports the Living Building Challenge by providing a transparent materials database that project teams can select from to meet the Red List requirements. There are three types of Declare Labels:

• Declared—This indicates 100 percent disclosure, but contains one or more Red List chemicals that are not covered by an existing exception.

• LBC Red List Approved—This indicates a minimum of 99 percent disclosure, but relies on one or more exceptions to demonstrate compliance.

• LBC Red List Free—This provides the highest assurance, indicating 100 percent disclosure and that the product does not contact any chemical on the LBC Red List.

Beyond complying with the CDPH’s state-specific requirements, and meeting ILFI’s Living Building Challenge 4.0 standard and Declare Label 2.0, products verified and certified for low VOC emissions also are recognized by Building Research Establishment Environmental Assessment Method (BREEAM), the Collaborative for High Performance Schools (CHPS) Criteria, Fitwel, and as mentioned earlier, USGBC’s LEED v4.1 and WELL v2.

In addition, ILFI, WELL, and LEED recognize and reward more expansive product ingredient reporting through health product declarations (HPDs).

Several ceiling products’ HPDs are publicly available and published through the Health Product Declaration Collaborative’s Open Standard v2.2. This voluntary, standard format uses basic inventory methodology for reporting product-level thresholds and compositional chemistry down to 1000 ppm.

Providing architects, interior designers, and specifiers with Declare Labels, HPDs, and other transparent certifications gives them the right information to evaluate and select ceiling products based on their merits and performance.


Corgan specified acoustic stone wool ceiling panels for Pioneer Natural Resources corporate offices in Irving, Texas. The office’s stone wool ceilings are certified for low-emitting products, provide 85 percent light reflectance for energy efficiency, and achieve an NRC of up to 0.95 for high sound absorption. Photo by Corgan/courtesy Rockfon

In every commercial building project, design and specification professionals balance aesthetic choices and performance requirements, including IEQ factors influencing people’s health and well-being.

While there are many choices in acoustic ceilings, stone wool’s inherent properties meet multiple performance criteria:

• Achieve high sound absorption, NRC 0.90 or higher, for an optimal acoustic experience;

• Support good IAQ, certified with GreenGuard Gold for low emissions and LBC Red List approved Declare Label;

• Resist moisture, humidity, and mold without antimicrobials;

• Provide high light reflectance, 0.85 or higher, contributing to energy efficiency; and

• Meet a Class A fire rating, indicating it will not spread flame or smoke.

As part of a suspended ceiling system, stone wool panels also:

• Deliver high durability and clean easily;

• Offer a 30-year standard warranty for most applications; and

• Provide access to the plenum for future building upgrades.

Working closely with a qualified ceiling system manufacturer will help ensure the project achieves its IEQ goals and other design objectives.

  1. [Image]:
  2. LEED v4.1’s:
  3. WELL v2 Pilot’s:
  4. Living Building Challenge 4.0:
  5. [Image]:
  6. U.S. General Services Administration’s Public Buildings Service (PBS):
  7. In many classrooms:
  8. one survey:
  9. [Image]:
  10. National Fire Protection Association (NFPA):
  11. 2021 International Building Code (IBC), Section 803:
  12. disadvantages of using antimicrobials:
  13. [Image]:
  14. According to the EPA:
  15. GreenGuard Gold Certification standard:
  16. Declare Label 2.0:
  17. [Image]:

Source URL: