Everything had to be done just right in the construction of The Great Lakes Center for the Arts in Petoskey, Mich.
With a tight acreage footprint in a scenic setting just steps from Little Traverse Bay, architects wanted a building that reflected the community but also offered the functionality required in the $25 million, 525-seat theater. Every detail in the 40,000-square-foot project was scrutinized to the utmost.
“Our team was challenged with the idea of creating a high-aesthetic center for the performing arts that met world-class levels for finish and quality of acoustics for all types of performances,’’ said Jason Novotny, the lead architect on the project for TowerPinkster, Grand Rapids, Mich.
That includes the smoke vents that sit atop the structure. TowerPinkster specified five acoustical smoke vents, manufactured by The BILCO Co., New Haven, Conn. Automatic smoke vents protect property and support firefighters in bringing a fire under control by removing smoke, heat and gases from a burning building. This will allow air quality and visibility to be maintained inside the theater so that patrons can exit safely, and firefighters can enter to fight the blaze.
The 4-foot by 8-foot smoke vents block outside noise that might seep into the center, where events range from concerts and speakers to movies and opera recitals.
“With the potential for more than 500 visitors for larger events, our team knew we would have a need for a dependable smoke ventilation system,” Novotny says. “With this being a high-performing acoustical environment, we designed a separate structure for the performance hall from the remainder of the building. This was solely for acoustical isolation of building elements. The BILCO acoustical smoke vents became a part of this ‘shell within a shell’ with their acoustical sound reducing characteristics.”
Acoustic smoke vents perform similar to standard vents but are designed to guard against noise intrusion. They are generally used at performance venues that seek to limit outside noise.
Acoustical smoke vents include Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC) ratings. The difference in the ratings is essential for architects, designers and construction teams to understand. For the Great Lakes Center and other performance venues, the key rating is OITC.
OITC rates the transmission sound between outdoor spaces and indoor spaces in a structure. The OITC rating was developed in 1990 and is typically used to measure sound transmission loss over a frequency range from 80 to 4000 hertz. It is most applicable for measuring the prevention of low frequency exterior sounds such as automotive traffic, construction and low-flying airplanes through exterior building surfaces.
“OITC is the preferred rating when addressing sound insulation from exterior noise – especially when transportation noise sources are impacting a building facade with significant low-frequency (bass) sound,” says Harold Merck, principal and acoustician for Merck & Hill Consultants of Atlanta. “While STC ratings may be fine for typical interior noise sources such as voices, STC doesn’t adequately address the extended low-frequency noise contribution of aircraft, traffic or even large roof-top equipment. The OITC better addresses low-frequency noise impacts and is the more applicable sound rating for roof mounted automatic smoke vents.”
STC measures the extent to which sound is prevented from being transferred from one area to another. The higher the STC value, the less that sound can be transferred through a building product. STC is typically used to measure sound transmission loss over a frequency range from 125 to 4000 hertz and is most applicable for interior areas that experience mid- to high-frequency noises, such as conversation, television, telephones and office equipment.
BILCO acoustical smoke vents carry an OITC-46 sound rating and an STC sound rating of 50. BILCO’s vent also has an ISO 140-18 Rainfall Sound Rating, which measures the impact sound insulation, roof, skylights and roof/ceiling systems incur when exposed to artificial rainfall. BILCO’s ACDSV rating of 37.5 dB features a nearly nine percent improvement over its previous four-cover smoke vent models.
BILCO smoke vents have been specified in a wide range of applications. Whether it’s a performance venue in Michigan, a concert hall in Cincinnati, or an exclusive private school in Massachusetts, the vents have played an important part in helping architects find a solution to controlling exterior noise.
Thomas Renner is a former newspaper editor who now works for Catalyst Marketing Communications in Stamford, Conn. Renner writes on building, construction, engineering, architecture and other trade industry topics for publications throughout the United States. For more information on The Bilco Co., New Haven, Conn., visit www.bilco.com.