Published in the May 2009 issue of Today’s Facility Manager
Regardless of whether a facility project involves a new addition or the renovation of an existing space, selecting an acoustical ceiling system requires the evaluation of a variety of factors. When choosing ceilings, facility managers (fms) should begin with the considerations most important to their buildings. In many cases, visual criteria will be an initial area of investigation.
However, while visual criteria are key to the aesthetic needs of a space, it is the performance related criteria that are vital to meeting an organization’s functional requirements. These include such essential factors as acoustic control and light reflectance. Several points that fms should keep in mind when examining and weighing these criteria during the selection process are acoustical performance, light reflectance, and maintenance demands.
Sound control is a vital performance criterion, especially when dealing with healthcare, education, and commercial office spaces.
In closed spaces, the main function of a ceiling is to limit the transmission of sound between adjacent rooms, especially when these spaces share a common plenum. In this case, a mineral fiber ceiling with a Noise Reduction Coefficient (NRC) of 0.55 to 0.65 and a Ceiling Attenuation Class (CAC) of 35 or higher is usually a good choice. [See sidebar for useful definitions.]
In open plan spaces, the main function of a ceiling is to absorb sound that would bounce off the structure into an adjacent space or cubicle. Here, a high performance fiberglass ceiling with an Articulation Class (AC) of 180 or higher is usually the best choice.
Sound absorption and light reflectance are vital to satisfactory ceiling selection criteria. As a result, it is important for fms to be familiar with the primary measures of a ceiling’s acoustical and light reflectance performance. The following terms are useful:
Noise Reduction Coefficient (NRC). Indicates the ability of a ceiling to absorb sound over all angles of incidence. It is expressed as a number between 0.00 and 1.00 and indicates the average percentage of sound that a ceiling absorbs. An NRC of 0.60 means the ceiling absorbs 60% of the sound that strikes it.
Articulation Class (AC). Indicates the ability of a ceiling to absorb sound at angles of incidence between 40° and 60°, the angles at which most sound passes over open plan furniture dividers. The higher the number, the better the ceiling performs as a sound absorber between open plan areas.
Ceiling Attenuation Class (CAC). Indicates the ability of a ceiling to block sound from penetrating the plenum of one closed space and transmitting it to an adjacent closed space that shares the same plenum. The higher the number, the better the ceiling performs as a barrier to sound intrusion between closed spaces.
Light Reflectance (LR) Value. Indicates the ability of a ceiling to reflect light. LRs range from 0.00 to 1.00 and denote the percent of light striking the panel that is reflected. An LR of 0.83 means the ceiling reflects 83% of the light that strikes it.
To attain satisfactory sound absorption, the metal panels should be perforated and backloaded with a type of liner or batt. Perforations vary in size depending on aesthetic appeal, although currently there are microperforated panels in which the holes are so small they are essentially invisible.
Perforated panels are usually supplied with a sound absorbent acoustical fleece liner or an encapsulated fiberglass batt behind the perforations. The NRC of perforated panels can range from 0.65 to 0.90 depending on the backing.
The prevalence of open plenum spaces in facilities, meaning those that have no ceiling and reveal building service elements such as the ductwork and piping, continues to increase. Unfortunately, this “warehouse look” can often cause acoustical problems because sound reflecting off the deck results in excessive reverberation.
However, noise issues related to open plenum designs in a facility can be addressed through the use of a number of different sound absorbing elements. One option is a type of pre-engineered ceiling system that provides sound absorption properties while maintaining the look and feel of exposed structure designs. This type of system can be installed onto an exposed deck, onto drywall, or suspended with wires, if desired. As an affordable method to retrofit open plenum spaces that suffer from poor acoustic performance, these ceiling panels feature an NRC of 0.90. And as a result, it is possible for panels installed over only 20% of an area to reduce reverberation by 50%.
Acoustical clouds and canopies, two types of “free floating” ceilings, are another way to add sound absorption in an open plenum space while supporting the exposed look. Visually, acoustical clouds are flat, while canopies are curved and can be installed as hills or valleys.
Designed for use in either new construction or retrofit applications, acoustical clouds and canopies suspended above work areas provide a type of interrupted ceiling plane. As such, they help control both the reflections between cubicles and distant reverberation noise, thus reducing occupant distractions.
Acoustical clouds and canopies can actually provide greater sound absorption than a continuous ceiling of the same surface area, because sound is absorbed on both the front and back surfaces of the cloud. The more “live” the space is, the greater the effect on reverberation time from the addition of clouds will be.
In many facilities, a growing awareness of energy saving lighting systems imparts a new importance on the role of the ceiling. This is because high light reflectance ceilings—those with a Light Reflectance (LR) value of at least 0.83—can make these lighting systems more effective while reducing energy costs and consumption.
The benefits are most significant with indirect lighting systems, because the ceiling is an integral part of the lighting distribution system. For example, in addition to increased light levels, fewer fixtures may be needed to obtain desired illumination levels. Having fewer fixtures means less energy is required to power them. It also translates to lower maintenance costs, since there are fewer lamps and ballasts to replace.
As sustainability becomes increasingly important in commercial and institutional facilities, so do the environmental qualities of the ceilings installed in those spaces. To help meet the green design needs of today’s buildings, for example, mineral fiber ceiling panels and fiberglass panels are available that contain high recycled content.
And ceiling panels are not the only element of a ceiling system that can incorporate high recycled content. Suspension or grid systems to support the ceiling panels are also available with high recycled content to help fms meet their organizations’ environmental goals.
Finally, when acoustical ceilings come to the end of their useful life, fms should consider recycling these materials rather than dumping them in a landfill. There are a number of industry programs that enable fms to ship their used ceilings to a manufacturer or other party as an alternative to landfill disposal. In some instances, the recipient pays freight costs for shipping the old ceilings (usually with a minimum square footage); many recipients then use the old ceilings for raw materials in the manufacture of new ceiling products.
When choosing the best ceiling for their facilities’ needs, fms will want to take into account aesthetics. However, as any fm knows, the performance of the ceiling system will be crucial to occupant satisfaction, ease of maintenance, and even interaction with building systems, such as lighting. Considering the prominent role of ceilings throughout a facility, it’s important for fms to get performance right from the start.
Brayman is vice president of marketing for Armstrong Commercial Ceiling Systems (www.armstrong.com/ceilings) located in Lancaster, PA..
The Design Impact Of Ceilings
By Ryan Favier, LEED® AP
Ceilings don’t always get the respect they deserve. Though easy to overlook or relegate to a purely functional role, ceilings can contribute significantly to the aesthetics, acoustics, personality, and culture of a facility environment.Several factors should inform a facility manager (fm)’s selection of the ideal ceiling solution for their space. Beyond issues of code compliance, safety, and maintenance demands, fms should also consider how the various ceiling options will contribute to the overall design, flexibility, and sustainability of their spaces.Whether designing a brand new facility or renovating an existing one, fms who make ceiling decisions must align their selections with an organization’s budgetary, functional, and aesthetic goals.
The appearance of a ceiling—even its height—can make a drastic difference in the overall environment below. Using a bold color or quirky detail can change the mood of a space. A facility may feel extremely confined, but raising the ceiling just 6″ to 12″ can dramatically change how occupants perceive the space. Even using shapes from the ceiling and mimicking them on the floor can give an excellent floor to ceiling relationship and can guide people through a space.
The standard tiled ceiling is still most commonly used because it performs well, is relatively inexpensive, and is easier to install than drywall. Still, organizations that are trendier and eager to make a statement—such as advertising agencies or high-tech firms—are often more willing to deviate from a standard ceiling.
Recognizing the significant role of ceilings in a facility’s design, architects and interior designers have requested that manufacturers explore new ways to use non-traditional materials to create products that are more flexible, practical, and sustainable. One of the most profound recent trends is the availability of sustainable ceiling products that are either biodegradable or that use recycled fibers or other materials.
Closely aligned with this trend is the widespread use of open [plenum] ceilings. Because these open ceilings use no materials, organizations may choose this option as a tangible illustration of their sustainability aspirations while also creating a dramatic design aesthetic.
But open ceilings can have their disadvantages. Acoustic issues can be problematic, because sound easily bounces off the mechanical equipment and ductwork overhead. Additionally, open ceilings also result in a very spacious feel, which is not always ideal for creating a private space. Also, some fms may think open ceilings look unfinished because of the exposure of mechanical equipment and ductwork, so it often comes down to personal preference.
New materials are becoming more appealing to those who select ceilings. Ten to 20 years ago, fms probably would have never considered a wood paneled ceiling because of problems with acoustics, but now these ceilings can be found in corporate headquarters and other types of offices to achieve an executive aesthetic. Some organizations even choose curved metal ceilings that can be molded into different shapes. Metal achieves a decorative or bold look that draws the eye to the space and illustrates a contemporary feel.
Larger paneled ceilings are becoming a popular choice for those organizations seeking a more traditional environment. Instead of using several individual tiles though, large sectioned panels can achieve a cleaner plane with no seams. This process has the monolithic properties of drywall but creates better access to mechanical equipment above.
Companies seeking to combine functionality with flair can use standard ceiling tiles throughout the majority of a workspace but incorporate a metal ceiling in a reception area, cafeteria, or other nook to offer an interesting design feature that adds to the overall environment.
No longer just a surface overhead, ceilings can dynamically shape the overall environment and impact of facility’s design.
Favier, LEED® AP (firstname.lastname@example.org) is an interior designer in the St. Louis office of HOK, a global architectural design firm. His role involves coordinating the design, documentation, and implementation processes for corporate office projects with challenging schedule and budget requirements. Favier earned his bachelor of interior architecture degree from Kansas State University.