Realizing ceiling potential
A ceiling is the largest and most critical surface in establishing a room’s performance and ambiance, yet it is often left as an afterthought in project development. Postscript planning can mean poor lighting and sound quality, which in turn can affect the productivity of occupants. A lack of forethought also can mean a lot of unnecessary work for maintenance crews.
When shopping for ceiling systems, the first question a facility executive must ask is, who will occupy the space and what will they be doing? Do the tasks performed in that space require confidentiality, speech intelligibility or low distractions?
“You have to understand what you’re trying to do with acoustics,” says Rik Master, architecture and construction systems manager for USG Corp. “Once you understand what you’re trying to do, then you can select a system that accomplishes the function you’re trying to achieve.”
By determining the purpose of the space and by understanding the ceiling’s relationship to that space, facility executives can make more informed decisions when selecting ceiling systems. Critical issues to consider when shopping for ceiling systems include acoustics, reflectivity, aesthetics, longevity and durability.
Acoustical factors are perhaps the most critical characteristics of ceiling performance. “The acoustical strategy in an office is different than in schools because the goals are different,” says Niklas Moeller, vice president of K.R. Moeller Associates Ltd. “In an office environment, you want to reduce intelligibility. You want speech privacy. In the classroom, you want speech intelligibility.”
In office environments, providing some speech privacy and reducing distractions can be a challenge. In open floor plans, sound travels up and over cubical partitions. Even when partitions are built to the ceiling, sound can still travel up to the deck and bounce down. Sound also can travel through ductwork, under doors and through any other crack in the room.
“If smoke can get through the space, then so can sound,” Master says. “Sound goes through the exact same holes. Granted, a sound wave is totally different than smoke, but if one gets through the other will.”
A good acoustical tile will absorb sound waves regardless of which direction they travel. A poor quality tile allows sound to seep in.
Means to an End
When noise reduction is the goal, it is important to look at the acoustic tiles’ NRC or CAC ratings. NRC — noise reduction coefficient — measures the amount of noise a panel can absorb, while CAC — ceiling attenuation class — measures the amount of sound passing through a panel. The more open the space, the higher the NRC rating must be to achieve good sound control, says Kim Graaskamp, director of sales and marketing for Hunter Douglas.
Where speech privacy is important, ceiling tiles should have a high sound transmission loss rating, such as a CAC of 35 or higher, and moderate sound absorption ratings, such as an NRC of .55 to .70, says Ken Roy of Armstrong World Industries.
Open floor plans, such as call centers, require low distractions. This kind of space requires a high-performance ceiling with an articulation class (AC) rating of 180 to 210 to reduce reflected sounds from adjacent cubicles, says Roy. Articulation class measures the sound reflected from the ceiling to adjacent workspaces.
However, not all interior designs call for suspended ceilings. Open-ceiling looks create new acoustical challenges for speech privacy, particularly when combined with standard deck heights. Options include spraying a sound-absorbing substance on the ceiling, which produces a cottony appearance. Perforated metal decking with sound absorbing material behind it is another choice.
Sound masking also improves privacy in open environments, Moeller says. Sound masking covers sound instead of absorbing it. “The goal is to generate a sound in space that is effective, but it also must be as unnoticeable as possible.”
A good masking system will accommodate a range of acoustical differences and provide consistent masking throughout space.
What works in open offices can be counterproductive in classrooms, auditoriums or other spaces where intelligibility is the goal. Sound-absorbing materials produce dead spaces and a monotonous acoustical environment, causing the listener to tune out.
A diffusive ceiling might be more appropriate in those settings. A diffusive ceiling scatters sound instead of soaking it up. The voice tends to envelop the space more powerfully, increasing the listener’s understanding or enjoyment.
“The key is to recognize that good noise control is only achieved when the designer follows a multipronged approach,” Moeller says. “There’s no single acoustical material or noise-control solution. Simply relying on one or two approaches does not produce a sufficient result.”
Confidentiality requirements associated with the Health Insurance Portability and Accountability Act of 1996 (HIPAA) make speech privacy in the healthcare industry particularly critical. The ceiling is a crucial line of defense in preventing sound from entering adjacent rooms. Consultants typically recommend a combination of acoustical tiles that absorb and block sound and sound masking systems that cover the sound.
“Part of the intent of the law was to improve healthcare facilities by preventing others from overhearing speech conversations,” says Fred Folsom, executive vice president of Dynasound. “Better ceiling sound absorption is part of that solution as well as the addition of sound masking.”
The Right Ambiance
At one time, the only aesthetic purpose of a ceiling was to hide wires and pipes. Fluorescent tubes provided enough light for everyone to see, so neither lighting issues nor room ambiance played a role in the selection of ceiling systems.
“Light reflectance is one of the least looked at issues,” says Folsom. “It is a softer issue, and facility executives probably don’t pay as much attention to it as they should.”
But that is changing. Studies show that natural light is more satisfying to building occupants than electric lighting, Master says. These studies have sparked a trend in architecture to unblock windows by moving offices to the center of a large space. Softer, indirect lighting is coming to replace traditional — and stark — direct fluorescent fixtures, which can cause glare on computer screens and give computer operators pounding headaches.
For these new lighting strategies to work, the ceiling must be capable of spreading light across larger areas.
“We want to see minimum 75 percent light reflectance, which most commercial ceilings provide,” Folsom says. “If indirect lighting is used, most designers want to see 80 to almost 90 percent reflectance.”
Beyond comfort, energy efficiency is perhaps the most critical benefit of a reflective ceiling.
“This high performance can result in lower operating costs as well as potentially fewer fixtures to generate the desired foot-candle level of illumination,” Folsom says.
Many states are legislating how many watts per square foot a building can use. For example, California’s energy code limits power usage to 1.2 watts per square foot. “You must be able to power everything, including light fixtures,” Graaskamp says. “This means that you must bounce light further into space to reduce the number of foot-candles per square foot.”
Indirect lighting systems also improve acoustical capabilities, Roy says. “Indirect lighting is a very good thing acoustically because the ceiling does not have lighting fixtures breaking up the plane.” This results in a more uniform application of ceiling tiles, which improves the ceiling absorption, both NRC and AC ratings, and the ceiling transmission loss, CAC rating.
Indirect lighting also can improve the ambiance of the room by improving the look of the ceiling.
“Some ceilings are prettier under indirect light,” Graaskamp says. “It hides the flatness of the surface.”
Architects are enlivening the ceiling with innovations in design and materials to create surfaces that are aesthetically pleasing as well as functional. With vaulted ceiling designs, architects can incorporate softer light effects with shelves of sound-absorbing material. The result is better overall performance in a more pleasing environment, Master says.
Even when the interior design calls for a dropped ceiling, architects are leaning toward cleaner, smoother looks, says Ann Miller, design manager for Armstrong. Tiles with fissures and holes are fading from popularity because they are unattractive.
Durability and Longevity
Tiles filled with fissures and holes also are less durable than tiles with higher densities, and that is a top concern for those who take care of the building.
The main benefit of a drop ceiling is to allow easy access to the cabling above it. Every time one of those panels must be taken down, durability becomes an issue. In the past, products with high NRC ratings typically were not very sturdy. However, the ceiling industry can provide good damage-resistant materials along with .70 and higher NRC ratings at the same time, Folsom says.
Durability becomes more of an issue when a panel is cut to accommodate lighting fixtures, air ducts, sprinklers, speakers or any other device suspended from the ceiling. Ceiling fixtures restrict access and should be placed in a pattern that reduces the number of tiles that must be perforated, Master says.
When the space above perforated tiles must be accessed, those tiles inevitably are torn out, which means they have to be replaced. This is one advantage of smaller tiles over larger ones, he says.
Dirt, mold and humidity are other factors that affect durability. It is much easier to replace soiled tiles than to clean them. Because dirty tiles are typically the result of lax building maintenance, changing filters regularly and preventing leaks reduce the need to change otherwise undamaged tiles, Graaskamp says.
Most major manufacturers now carry product lines that are made for humid climates. Other products are designed to inhibit the growth of mold and mildew. Schools in the South are an example of where these products would be particularly beneficial, Graaskamp says. During the summer, air conditioners are shut off and the buildings become hot and damp, creating an opportune environment for mold and mildew. Panels made from inorganic materials tend to resist mold growth better than organic materials.
Most acoustical tiles are designed to last about a decade, but longevity is less of an issue as people’s tastes change and colors and textures go in and out of style with some regularity, Master says.
The most important question to ask in terms of longevity is, how available are replacement panels? Off-the-shelf panels are more cost-effective and more readily available than custom panels.
Facility executives will make better design and material choices by focusing on the purpose of the space and the needs of its occupants. Advance planning and research can assure that the light and sound characteristics of a ceiling system blend to produce a comfortable, productive work space while reducing unnecessary work for maintenance crews.
Lynn Proctor Windle, a contributing editor for Building Operating Management, is a freelance writer who has written extensively about real estate.