Ceiling Technology and Aesthetics

Innovative ways to boost performance while adding color and pattern

C.C. Sullivan

The application of design sensibility to what some architects call “the fifth wall”—the ceiling plane—brings a number of specific challenges that impact building effectiveness and indoor environmental quality (IEQ). Chief among them is design treatment, including the use of color, texture, and form without compromising performance or incurring excessive cost. Other challenges include acoustical performance, which has a direct effect on human productivity and health, yet may conflict with the use of large monolithic planes or the use of special shapes and visual effects. Sustainable design goals often fade in the drive for low-cost, low-value ceiling systems.

Yet a good ceiling specification can benefit indoor-air quality, energy efficiency, daylighting efficacy, and long-term building operations. New tests for flame spread and smoke development help ensure ceilings are safer, too. In sum, ceiling design has a direct effect on the facility's return on investment, or ROI.

In addition, architects are increasingly taking advantage of innovative design techniques that elevate the fifth wall to a higher plane, so to speak, in terms of advancing architecture. A slew of innovations have emerged for ceiling design, including new sizes, shapes, color, and patterns as well as systems for supporting the assemblies and accessing the plenum above.

Innovative techniques for printing and patterning interior surfaces are available, often using fewer material resources than traditional ceiling treatments. Some of these manufacturing technologies allow cost-effective custom runs to match a project's design needs, while retaining desired acoustical and lighting properties. In many cases, they contribute to better occupant health and safer, more sustainable buildings—and more visually impressive interior spaces.

A Short History of Modern Ceilings

A look back at the development of suspended ceiling technology provides helpful context for understanding today's advances. “Eighty to ninety years ago, suspended ceilings were invented to hide HVAC ducts, pipes, and other systems routed along the ceiling,” says Ko Kuperus, general manager at Hunter Douglas Contract, Denver. “The acoustic tiles were dropped into metal grid, and the same is true today. The concept has not changed in almost 100 years.”

New techniques for applying color on ceiling systems enliven meeting offices. Other treatments include geometric faux finishes that mimic leather, Venetian plasters, wood grain, and metals. Image courtesy of Hunter Douglas Contract

True, it has become a cliché of modern construction and the architect's default spec. Suspended ceilings are also known as false ceilings and dropped or drop ceilings. The concept was created as a secondary ceiling plane, typically hung from the steel beams or a concrete or metal structural deck above. “Acoustical ceiling tiles have typically been smooth and white or off-white, with little in the way of a pattern,” says Hiro Isogai, a principal with WDG Interior Architecture in Washington, D.C. Estimates by Kuperus suggest that at least 90 percent of the applications have historically been white—“a missed opportunity for design,” he adds.

The metal grid suspension system has been integral to the systems. Companies such as Chicago Metallic Sash Co., which made zinc profiles for stained glass windows in the early 1900s that were popular among architects like Frank Lloyd Wright, began shifting to the manufacture of ceiling suspension grids in the 1930s, often using a 5/8-inch metal profile. Contractors in Florida adopted channel moldings—typically used for exterior siding in the 1950s—as trim to support acoustical ceilings inside houses, which would not easily nail into the masonry walls or ceilings.

New ceiling systems offer more methods for creating articulations in the grid ceiling surfaces. Many of these mimic traditional or alternative ceiling materials, such as this faux wood treatment. Image courtesy of Hunter Douglas Contract

The system was popularized by companies like Acousti Engineering Co. in Florida and by many companies elsewhere. An American patent was awarded in 1961 for the concept of “Accessible Suspended Ceiling Construction,” decades after the product had been in common use in Europe and the United States. Some suspension-type ceilings had inverted T-shaped members to support ceiling tiles. Since then, others have used a concealed grid system of Z-shaped bars with splines to connect interlocking panels. While the concealed grids allow access to the interstitial space above by means of a key panel, the drop-in ceiling tiles have been seen as more convenient, allowing faster access.

Yet the concealed grid held appeal among many architects because of its sleek, monolithic presentation, which worked well with mid-century modern interiors for offices and other nonresidential settings. Eventually, the trend toward larger tile sizes and more concealed suspension grids became an important objective for architects, according to Jeffrey L. Fullerton, a LEED-accredited director of architectural acoustics with Cambridge, Massachusetts-based consultant Acentech. Suspended ceilings were seen as an alternative to surface-applied products such as troweled plaster, creating larger expanses of uninterrupted surface area with minimal reveals or joints—an effect similar to drywall, says Fullerton.

In parallel with this trend toward smaller reveals and smoother surfaces, other architectural styles demanded articulations to the grid ceiling surfaces. Suspended ceiling systems were developed with stamped or sculpted tiles that produced optical patterns or effects that echoed traditional worked plaster or metal panels or suggested coffered, cove or beam-style ceilings. Many architects maintained traditional or alternative ceiling materials, included plasters, gypsum board, wood, and pressed or perforated metal panels. Some ceiling systems employed a stretched fabric, such as polyester or polyvinyl chloride (PVC), over a light metal or plastic frame.

While traditional ceiling techniques have included moldings, rosettes, wood panels or trims, and colored paints, the modern suspended ceiling tended toward white and lightly textured surfaces. In most cases, color and pattern applied to the ceiling systems—whether in manufacture or on the jobsite—has been relatively rare.

Trade-Offs in Design and Performance

In spite of the limitations, in much of the market the roll-formed suspension systems have become a habitual spec—and the bane of many architects interested in more creative ceiling treatments. One reason has been that typical cellulose ceiling tiles could not be made much larger than 2 feet or 3 feet in length; they would sag over time, or fall out of the grid. Another was the limitation placed on interior aesthetics by the commercial products.

In places where acoustics are important, such as this transit station, painting the ceiling surface after manufacturing can change its noise reduction coefficient (NRC). Image courtesy of Hunter Douglas Contract

One reaction was the antithesis of the suspended system: Architects started to favor the open ceiling, with structural elements and mechanical, electrical, and plumbing (MEP) systems exposed for visual effect. This style emerged and found adherents in 1970s and 1980s commercial construction, led by “functionalist” architects like Richard Rogers and Renzo Piano, with their seminal Centre Pompidou in Paris (1971) and the Lloyd's of London office building. “This framework must allow people to perform freely inside and out, to change and adapt in answer to technical or client needs,” said the architects.

Yet open ceilings tend to suffer from poor acoustical performance. On top of that, the convenience and cost-benefit equation provided by suspended grids has proved too good to leave behind. For these reasons, architects have looked for alternatives to cellulose, such as fiberglass, metal, cellular plastic mats, and stretched fabric, among others. Advances in ceiling systems over the last few years have opened up new possibilities for larger ceiling panels and the application of new design ideas, says Kuperus. “On the one hand, manufacturers have made sizes of demountable tiles much larger, so you can still service the plenum volume above but through larger smooth areas with fewer joints and reveals,” he explains. “Another advent was the introduction of colors and patterning in the systems.”

New techniques for applying color and pattern have included geometric patterns and faux finishes that mimic leather, Venetian plasters, wood grain, and the like, as well as painted metals and thin wood veneers over a metal substrate. Some of these finishes are applied on site, often by skilled trades. Other finish solutions are factory applied, which reduces work on the jobsite and, in some cases, the amount of coatings and associated volatile organic compounds (VOCs) introduced in construction.

Two recent trends have contributed to interest in color and pattern in ceiling systems. One has been the movement toward therapeutic environments. Typically associated with healthcare facilities, these psycho-socially supportive spaces can benefit patient recovery and satisfaction as well as organizational productivity and outcomes, according to HOK senior associate Ron Smith, AIA, ACHA, and Nicholas Watkins, Ph.D., HOK's director of research and innovation. “The effects can be positive or negative,” they wrote in the Whole Building Design Guide. “No environment is neutral.”

Therapeutic environments in healthcare buildings, schools and other facilities include the use of chromatherapy to positively affect the experience of occupants and visitors. Image courtesy of Hunter Douglas Contract

The principle that colors may have medical value or healing benefits is known as color therapy or chromatherapy, according to PVA Architecture's Maryia A. Boykins, Assoc. AIA, who notes that the seven discrete primary colors of the visible spectrum “improve balance and healing in the mind and body.” In his seminal studies on the subject, Roger Ulrich, Ph.D., of Texas A&M University, has called color and pattern a “positive distraction” to explain this therapeutic effect.

While the effects of chromatherapy have been considered as part of evidence-based design (EBD) studies for healthcare environments, they are seen as useful for other building types, too. In a recent white paper on correctional facility design commissioned by Norix Group,¹ the designer Tara Rae Hill, ASID, observed, “Leading research shows that interiors which have an interesting use of material and color and that are not overly neutral will increase morale and mental well-being, ultimately reducing inmate and staff anxieties.” Color selection also impacts spatial perception and the “visual weight” of interior surfaces, according to color experts at paint manufacturer Sherwin-Williams.² For example, solids and simple patterns reduce visual weight while bold patterns add visual weight; for ceilings, light colors tend to attract attention, while dark-colored ceilings tend to direct the occupant's eye back to walls, furnishings and accessories in a room. Applied to the ceiling, red hues tend to be “weighty and annoying,” while orange can be “energizing.”

A second trend involves manufacturing advances supporting the use of visual effects on ceiling panels. In addition to more precise assemblies, there have been more curved and articulated shapes that still conform to a regular grid of square or rectangular supports. In addition, the emergence of mass customization has exploited flexible, computer-aided manufacturing systems to produce individualized, custom output while still keeping unit costs low.

Mass customization is based on methods for “effectively postponing the task of differentiating a product for a specific customer until the latest possible point in the supply network,” as explained in Operations Management for Competitive Advantage (McGraw-Hill/Irwin, 2006).

With a growing belief that ceilings can contribute more to interior architecture—and with supplier processes that support the need—today more architects are adding color and pattern to ceilings, wall panels and other surfaces.

Rediscovering Ceiling Color and Pattern

Beyond its performance in the physics of sound, light and air, ceilings are vital aesthetic elements in architecture. Since Michelangelo finished painting the vaults of the Sistine Chapel in Vatican City in the fall of 1512, architects have looked for ways to encourage visitors of their buildings to look upward, as if to the heavens, for inspiration and enjoyment. On today's ceiling surfaces, that often means applied colors, textures, patterns, and special lighting fixtures. As the architect Jack Diamond, principal at Diamond and Schmitt Architects of Toronto, has said, once the project team has established the objectives for a building project, “Colors and textures become an integral means of achieving design ends.”

In Michelangelo's day, paint was a common treatment for ceilings, and that remained true for centuries. For suspended grids and tiles, however, paint may not be ideal. Though custom matching colors are frequently applied on the jobsite rather than in the factory—mainly because the majority of ceiling systems are stocked only in white—painting an acoustical surface changes its noise reduction coefficient (NRC) and ceiling attenuation class (CAC) properties. The coatings may also introduce VOCs and other chemicals into the indoor environment. Architects must proceed with care.

Many suspended acoustical ceilings offer low-VOC formulations for their panel components, binders, glues, coloring agents, and metal profiles, which benefits indoor air quality (IAQ). Image courtesy of Hunter Douglas Contract

As an alternative, ceiling panels are now manufactured with factory-applied color, patterning, and either optical or tactile textures. This brings a few benefits to sustainable design: First, less energy and coloring agent and fewer resources are expended—in some cases, up to 25 times less pigmentation material by volume or weight. Second, a significant portion of the VOCs or toxins are captured in a controlled industrial environment. Third, in many cases there is greater range of application technique and effect at the factory or shop—in other words, greater design flexibility and more surface presentations for the architect to choose from.

Moreover, not all manufacturing approaches are alike. Some industrial coloring systems require large amounts of dye and pigment in order to produce a visually effective surface. Other, newer processes reduce the base materials needed, making the products relatively more efficient in terms of resources needed. In addition, some coloring methods produce no VOCs at all, and some use air instead of water to convey the dye, so that no hazardous waste is emitted and water waste is reduced or eliminated.

In addition, recent advances in pigmentation and visual effects have been adopted in the manufacture of architectural surfaces, fabrics, wallcoverings, and ceiling materials. One of the most valuable is sublimation printing technology, also known as dye sublimation. The process combines dyeing, or impregnating color into a material, with a phase change process that goes directly from solid to gas—called sublimation—without the materials becoming liquid. While the term is used to describe how inkjet printers work, industrial processors for interior finishes such as ceiling panels are very different: Solid dye particles are changed into gas using heat and pressure, then bonded with polymers present on the target surface, and then return to their solid state.³

The colorant particles employed in dye sublimation printing are engineered to bond with polymers only. This means that higher levels of certain materials in the substrate, such as polyester and rubber, will tend to attract and bond with more dye material. For ceramics, glass and metals, a polymer coating (usually a polyester liquid) can be heat-applied so that the dye sublimation process adheres to the surfaces. Done properly, the process results in brighter color rendition and longer-lasting surface treatment than many other coloring methods, with less fading and discoloration over time.

Dye sublimation is an effective approach for a range of product processes, including digital textile printing—for fabrics and wallcoverings, for example—and digitally produced signage. As compared to UV-curable, latex, or solvent printing, the resulting materials are known for a high-end feel or texture—called hand in the interior finish industry. That means the final product stands up to close inspection by building occupants.

Mass Customization of Interiors

There are other benefits to the innovative color-printing processes enabled by dye sublimation. The techniques are highly efficient and allow for quick changes in the selected digital inputs, meaning that a custom run of ceiling tiles can be accomplished at a low relative cost. This is one reason that sublimation printing has become popular in such industries as point-of-purchase signage, entertainment, events, and exhibitions.

Ceiling Materials and Lighting

An element of sustainable interiors is the use of the ceiling plane to reflect daylight as well as electrical illumination to maximize lumen efficacy. This also improves the comfort and usability of interior spaces. A common measure of the light reflectance of a ceiling material is ASTM E 1477 for Light Reflectance (LR-1). A level of about 75% is considered good, although higher levels are possible.

In addition, the resulting patterns or images on sublimation printed surfaces tend to have a clearer, more “perfected” image with the potential for sharper color contrasts, as compared to historical coloring approaches for architectural materials. Surface imagery has been developed to mimic wood, leather, concrete, Venetian plasters, and the like. The designs are applied to translucent materials as well, which can be used with backlighting to create a glowing appearance or a startling effect such as a glimmering pattern or a luminous faux wood grain.

Put these two elements together, and you have a “new category of ceiling material,” says Kuperus, whose company began working with the techniques in 2010. “The technology has brought more colors and prints into the interior, including faux finishes that typically have been hand-applied by the trades onsite. Now they are produced with photographic clarity by the manufacturer using very efficient customization techniques.”

In fact, say producers, the methods have allowed manufacturing to become entirely “made to measure,” a significant change for an industry where stock colors and patterns are the rule, not the exception. This is a practical implication of mass customization, say architects such as Philadelphia-based KieranTimberlake: Their designs can more easily create bespoke results without associated disadvantages in product cost or project scheduling. The architects contend that offsite production of building are “less expensive, more sustainable, and offer tolerances and techniques not possible in on-site construction.”

Nor is mass-customization a step away from architectural craft: In their book Refabricating Architecture, the architects show how mass-custom manufacturing extends the work of early modernists such as Le Corbusier, who used industrialized construction to serve a larger audience with better, less expensive and more quickly built architecture.

“For interiors, this means an unprecedented range of design choices,” says Kuperus. “Every architect now effectively has access to a vast, digital design library of thousands of colors—including color-matching to any major paint manufacturer—as well as a wide range of optical textures and surface patterns, at a reasonable cost.”

Recent projects employing these industrial techniques have included a University of Cincinnati facility, Heritage Hall, where images were “printed on” a ceiling system, according to creative director Brian Weatherford of Perkins+Will Eva Maddox Branded Environments, which consulted to the architect Bernard Tschumi.

“Originally we thought we might apply film so that the images would be changeable,” Weatherford explains. “But because the ceilings are perforated with an acoustical backing, we said, 'What if we print right on the ceiling panels instead?'” The sepia-toned imagery, which touts the university's sports and academic programs, is a major design feature in an impressive four-story atrium.

Ceiling systems can be specified for green building projects, including LEED for Schools, by considering the contribution to energy performance, recycled content, material reuse, and indoor environmental quality (IEQ). Image courtesy of Hunter Douglas Contract

Technology, Performance, and Sustainability

One of the challenges of these projects is determining the impact of the printed or colored ceiling on project sustainability. At the University of Cincinnati, for example, the printed ceiling system was made of up to 95 percent recycled materials and would provide a good level of light reflectance. The product was considered durable and resilient, including the images themselves, which resist fading and discoloration. In addition, the manufacturing process would minimize resource consumption over the project life cycle and limit VOCs introduced in the building.

With all this evidence, it still may seem that the impact of a ceiling solution on an assessment of sustainability is indirect and not immediate; the ramifications may not seem especially significant when compared to the impact of MEP systems or enclosure design, for example.

In fact, ceiling systems can be specified for adequate or even superior sustainability without creating a burden for the designer, contractor or client. Ceilings are integral to proper lighting, conditioning and environment, and should be considered as much a target for sustainable design as any building system.

As a general guideline, LEED for Commercial Interiors (LEED-CI) delineates three categories in which a ceiling system may impact green building goals:

Energy & Atmosphere: EA Credits 1.1-4 (Optimize Energy Performance) can be affected by a ceiling system choice, in large part because of its interaction with lighting and HVAC systems. Properly designed and constructed suspended ceilings, for example, play a role in limiting the conditioned space required for a building interior.

Materials & Resources: The specified ceiling should meet goals for recycled content, recyclable collection, regional materials, and renewables. Where possible, materials reuse is possible—for example by reconditioning or simply reusing a ceiling grid with new panels, which is increasingly common. Other areas for MR credit include construction waste management—which may be eased by using an engineered ceiling system rather than a fully site-built assembly—and optimization for intended use of the space by the likely tenant.

IEQ: Sustainable design promotes occupant health (and the health of the construction crew) as much as it reduces environmental impact. A ceiling system can impact occupants in the areas of ventilation, VOC emissions, lighting and thermal system control, thermal comfort, use of daylight for natural illumination, and optimization of outdoor view availability.

One aspect of IEQ not covered by all LEED requirements is nevertheless very important for occupant health and comfort: acoustics. Often the impact of acoustical performance is more easily measurable in occupant productivity or welfare than in direct effect upon health. But even performance is tied to sustainability: An interior environment that impacts its occupants negatively in any way is, by definition, unsustainable.

Energy & Atmosphere

The most recent major industry study on the effect of ceiling design on energy use came from the Ceilings & Interior Systems Construction Association (CISCA) in 2008. Conducted by Barry Donaldson & Associates, the study compared life-cycle analyses of continuous ceilings versus open-plenum environments; the results indicated that while construction costs for suspended ceilings were generally higher, the simple payback could be as fast as seven months in some retail applications or 3.5 years in some office and commercial applications, depending on factors such as climate, construction cost, and energy cost.

What's more, the life-cycle payback analysis proved to be positive: as low as nine months for retail and five years for office buildings. Only in Chicago did the life-cycle payback period stretch to greater than 10 years. CISCA's study suggests some reasons that suspended ceilings may create long-term savings:

1. Suspended ceilings systems use “a return-air plenum with lower static pressures and fan horsepower” rather than ducted air returns.
2. Return-air plenums are more efficient at removing heat from lights, reducing the air conditioning load.
3. Suspended ceilings boast higher light reflectance values than other ceiling types, meaning lower energy costs for space illumination, all things equal.

Energy savings reported in the study ranged from 9 percent to 10.3 percent for office applications, and 12.7 percent to 17 percent for retail.

Materials & Resources

“Sustainable design is a double-edged sword,” says Dean Hofelich, a senior designer and associate at LDa Architecture and Interiors, Cambridge, Mass., “in the respect that it helps narrow the field of potential finish materials.” Like other interiors experts, Hofelich laments that the field can sometimes be too narrow, but the point is an important one: Certain materials and systems are simply much more sustainable choices than others.

Suspended systems are, in general, a good choice because the base materials “are of recycled content, and can be recycled,” Hofelich explains. Some designers consider the open plenum choice to be a greener choice, because literally “de-materializing” the ceiling would reduce the simple quantity of resources used to build. But as is borne out in the CISCA life-cycle study, there are other implications of that choice more keenly felt in the long run.

After figuring for such considerations as locally sourcing materials, managing construction waste, recycled content, and recyclability, the designer must then consider the intended use in order to properly specify for durability, maintenance, and restorability. In terms of resilience, one potential downside of a suspended ceiling is the ongoing need to access the plenum to maintain other systems—lighting, electrical, HVAC, and data/telecommunications cabling; each time a tile is removed or handled for access, there is some material deterioration of both the grid and the tile. This leads to replacing access panels, tracks, and tiles, and eventually may require refurbishment or replacement of the entire ceiling.

Some types of ceilings are more robust than others, say architects, although the typical cellulose panels in soft metal grids are similarly resilient, says WDG Interior Architecture's Isogai. “We don't see a lot of difference in the performance of different types of suspended ceilings,” he explains. “What we see is that the required maintenance and repair of interacting systems determines the wear-and-tear on the suspended ceiling.”

Another maintenance aspect unrelated to accessing the plenum, says Isogai, but just as common, also involves HVAC system operation. “At the air diffuser locations and return-air registers the ceiling tends to get dirty,” he says, adding, “It is a real challenge to avoid that.” According to ceiling consultants, soil-resistant finishes are available that ameliorate this effect.

Indoor Environmental Quality

Most manufacturers of ceiling products, whether components of suspended systems or finishes for open plenum spaces, offer low-VOC emitting options for the binders, glues, coloring agents, and other component materials used in the ceiling panels and metal profiles. Increasingly, vendors have made the low-VOC feature a standard offering, recognizing the impact of interior finishes on indoor air quality (IAQ).

Other elements of a sustainably designed ceiling might include a reflective finish that enhances a natural daylighting strategy by bouncing light from windows further into the building. Ceilings can also be specified to soften and diffuse harvested daylight in the same way. In each case, the light reflectance (LR) value can have an effect on other performance attributes, such as acoustics.

A suspended acoustical ceiling typically reflects about 75 percent of the light striking its surface,⁴ for an LR value of 0.75. Yet there are recent advances in material and finish technology meant to increase the LR values in order to improve the energy efficiency and overall efficacy of indirect ambient ceiling lighting. Reflecting up to 90 percent of the light that hits their surfaces for a value of about LR 0.90, these newer products can help improve the brightness of interior spaces and reduce energy use by as much as 18 percent, according to the study “Performance Benefits of High-Reflectance Ceilings” by the Weidt Group, an energy and environmental consultancy headquartered in Denver.

Other benefits of high-LR ceilings according to the Weidt Group analysis include better balance of light diffusion—which helps improve occupant comfort and productivity while reducing the potential for glare. Also there is an associated reduction in light-loss factors (LLFs), the measured variables that determine horizontal illuminance or light level (lumens) available in a building space. Most of the LLF inputs are related to lighting system performance: lamp lumen depreciation, ballast factor, and luminaire dirt depreciation. A fourth measure, called room-surface dirt depreciation (RSDD) adds an LLF for dust and soil accumulation on all room surfaces, but especially the upper walls and ceiling. RSDD can be estimated from handbook tables in IESNA Lighting Handbook.

The light reflectance of a ceiling in the United States is generally given by the standard ASTM E 1477-98, Standard Test Method for Luminous Reflectance Factor of Acoustical Materials by Use of Integrating-Sphere Reflectometers. The test is a component of the ASTM Classification E 1264, which determines the luminous reflectance factor (LRF).

Luminous reflectance factor is often conflated with the measure light reflectance value, or LRV. Yet LRF and LRV are distinct measures: LRF can be described as “the color contrast between two material surfaces,” while the LRV quantifies how much light is reflected; if less light is reflected, the LRV will be lower. Color and texture have an important effect on LRV.

Renewed Focus on Acoustics

Whether colored or white, flat or shaped, the ceiling surface is important for integrating various building functions including illumination, acoustics, comfort, and other environmental controls.

Arguably the most valuable contribution of the modern hung ceiling has been in acoustical performance, often in settings where walls and floors are hard and impermeable. “Ceiling tile is good for sound attenuation, and on a case-by-case basis a buffer can be added on top of the ceiling grid and tiles for additional attenuation,” says WDG's Isogai. “We have to be careful with drywall ceilings; they can bounce sound back, although curved shapes can mitigate this. But if we are considering drywall ceiling for an area with stone, tile or similar finishes on the walls and floors, we have to be careful.”

Different materials have varying noise reduction coefficient (NRC) values over a range of noise frequencies. A fabric ceiling panel (blue line) is compared to a mineral fiber material. Image courtesy of Hunter Douglas Contract

Ceiling tile materials used have included porous blends of pressed cellulose, cork, mineral wool, clay, perlite, and starch, as well as foam backings and other soft acoustical mats of natural and synthetic substances. The products absorb noise but may also attract or retain moisture, and tiles or sections must be replaced once wetted by errant HVAC condensation, for example. However, they offer good acoustical performance, which is increasingly valuable for building design.

Noise levels in commercial and institutional buildings have been trending upward, according to acousticians and public health experts. The acoustical environment is a sum of several factors:

• Direct sound—for example, the path from a speaker to a listener.
• Reflected sound—which travels from the source and off interior surfaces and then to the recipient.
• Reverberation—or the persistence reflected sound, often quantified as reverberation time to describe how long it takes for reflected sound to become unintelligible.
• Background noise—generally includes undesired ambient noise sources indoors, such as mechanical system sounds, as well as outdoors.

The resilient floors and painted walls of concrete block in typical U.S. school classrooms, for example, often contribute to long reverberation times for very poor acoustics, limiting speech intelligibility by 25 percent or more, according to a seminal University of Kansas study.

In hospitals, where speech intelligibility can be a matter of life or death, interior noise levels have been increasing by about 4.0 decibels every decade over the last 50 years, a Johns Hopkins study⁵ concluded in 2005. Average sound levels in some healthcare environments are greater than that for conversational speech—about 50 decibels (dBA)—due to longer reverberation times and HVAC system background noise.

With these challenges in mind, acoustics are drawing increasing scrutiny in healthy, sustainable building design. Credit for effective sound isolation, acoustical finishes, and room noise are codified in standards such as U.S. Green Building Council's LEED certification programs for education and healthcare facilities. The baseline performance in LEED for Schools is drawn from the American National Standards Institute (ANSI) Classroom Acoustics Standard, ANSI S12.60. In LEED for Healthcare, the reference standards include Guidelines for Design and Construction of Health Care Facilities, authored by the Facility Guidelines Institute/American Society for Healthcare Engineering (FGI/ASHE). Acoustical consultants see the green building standards as a minimum performance threshold, however.

For acoustical finishes such as the ceiling system, the basic variables for performance include the noise reduction coefficient (NRC), which describes how much sound energy is absorbed by a surface. NRC values range from 0 (perfect reflection) to 1 (perfect absorption); for ceiling acoustics, higher values are better. A similar measure is sound absorption average or SAA, which is calculated over a wide range of frequencies from 100 hertz to 500 hertz; this broadband average is valuable as an accurate measure of the total sound absorption characteristics of a ceiling panel.

A third measure of use to architects is sound transmission class, or STC, which describes how well a building assembly attenuates airborne sound. The ASTM method for calculating STC has changed considerably over the decades. An STC of 25 means that normal speech can be easily heard through the partition or floor-ceiling assembly; an STC of 50 or 60 provides very good to superior soundproofing.

Last, the measure CAC or ceiling attenuation class is an acoustical rating specifically designed for ceiling materials, to describe room-to-room sound transmission in a commercial setting. Because interior partitions in commercial buildings often do not extend to the roof deck or floor decks, noise can travel over interior walls through the open plenum; ceiling systems with high CAC numbers are designed to prevent this.

For this reason, ceilings often need to be both an acoustical absorber (to reduce reverberation) and an acoustical barrier (to block noise). So the choice of a suspended ceiling tile material—and backers, in some cases—is likely to be a carefully orchestrated compromise. Ceiling materials or systems must offer a high NRC of more than 0.5, and new products and systems now offer very good acoustical performance, which NRC and SAA values of 0.85 to 0.90 and better.

Tested NRC and STC ratings are part of the equation, but the architecture and engineering team must consider more than the acoustical properties of different materials and systems; it is also important to know how sound is transmitted, and where it is suitable to use particular sound-isolating or insulating materials or assemblies.

Specifying High-Performance Ceilings

In addition to acoustical performance, the considerations for selecting and specifying ceiling assemblies include durability, toxicity, recycled content, and luminous reflectance, which is impacted by color and physical texture. The luminous reflectance levels of all interior surfaces—including ceiling assemblies —are considered together to estimate the level of illumination in the space. Other key considerations for selecting and specifying ceiling assemblies include:

Acoustics. As described earlier, this important element of IEQ is impacted substantially by ceiling choice. Acoustical ratings inform the design solution, with NRC values near 0.85 and an SAA of 0.89 providing a good performance benchmark.

Fire performance. The contribution of ceiling systems to smoke development and flame spread is vital to occupant safety. Selected materials should meet Class A requirements per the standard ASTM E84 for surface burning, with flame spread values below 25 and smoke development ratings of less than 50.

Resources consumed. Suspended ceiling systems tend to be light and low in resources required. Some newer panel designs weigh as little as 0.25 pounds per square foot, using half as many input resources as are required for older ceiling grid designs. In addition, some ceiling products allow for attachment of new ceiling panels to existing suspended T-grids. Others can be mounted directly to drywall and decks, as well as vertical surfaces. Lightweight construction means less landfill waste at the end of the product life.

IEQ. In addition to acoustics, IEQ considerations include the introduction of VOCs in the ceiling materials, coatings, and accessories. Room air quality may be improved by using factory-applied treatments rather than paint or similar on the jobsite.

Energy efficiency and IEQ. Lighting quality is affected by ceiling choice, which affects both occupant health and productivity—IEQ—and the efficacy of daylighting and electrical illumination, which affect energy efficiency. While brightness isn't everything, in general more reflectance means more usable light, reduced energy costs, and even reduced eyestrain among building occupants.

Durability and resilience. For longer life cycles and more permanent, sustainable buildings, the ceiling products should meet criteria for expected wear and tear. The moisture resistance of some ceiling products, for example, is rated up to 95% humidity in 104 degrees F temperatures. For fungal resistance, the products should meet ASTM C 1338 or a similar standard.

Structural and operational benefits. Many suspended ceiling technologies provide access panels or hardware such as a panel hinge or clip. These panels may not need to be touched during routine maintenance, as opposed to those with the concealed spline. Suspension rods and clips vary in design, but must be secure to the building structure; rails and T-sections must provide for stable attachments. Standard commercial grids offer the economical benefit of replacing ceiling panels or tiles as needed.

Color, texture, and visual interest. Add to this list of common considerations a relatively unexplored performance variable: aesthetics. Studies have demonstrated the therapeutic benefits and visual effects related to color and pattern, making them an important part of interior architecture.

While these considerations are important in ceiling choice, they are hardly comprehensive. Additional features of a ceiling system choice can be determined based on the particular needs of a project and the advice of consultants expert in acoustics, lighting and energy design, occupant health, and green building.

In general, however, it's likely that a carefully specified new ceiling system will meet many of today's requirements for high-performance interiors. Unlike the early days of suspended acoustical tile, today architects benefit from decades of manufacturer R&D to ensure a robust, effective “fifth wall.” Even better, these systems could portend a wider use of color, light, and pattern overhead, making our building interiors more expressive and stimulating than ever before.

Chris Sullivan is principal of C.C. Sullivan, a communications consulting and marketing agency focused on architecture and building products.

ENDNOTES
1	www.norix.com/pdf/norix_color_whitesheet.pdf
2	www.sherwin-williams.com/press/consumer/story/story4/
3	www.dyesub.org/
4	www.armstrong.com/commceilingsna/popup13021.html
5	www.aip.org/asa_laypapers2011/Mahapatra.html

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