By Joann Davis Brayman
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.
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..