Acoustics and Curves Under the Microscope at BECMarch 7th, 2018 | Category: Industry News
With growing cities comes growing noise concerns. People are living and working closer together. As a result, noise is becoming an overwhelming problem. At the 2018 Building Envelope Contractors (BEC) Conference in Las Vegas, a panel of acoustical glass experts addressed that concern. The conference, which ended at noon yesterday also included a separate panel focused on the possibilities of curved glass with today’s technologies.
According to Julia Schimmelpenningh of Eastman Chemical Co., noise is one of the top three types of pollution.
“Noise is an underestimated threat. It can cause physiological and neurological problems,” she said. “Noise can cause irritability, affect the ability to learn, create poor work performance and affect quality of life. People think you get used to noise, but our body reacts every single time.”
Schimmelpenningh acknowledged the (mis)perception that the greater the use of glass on a project, the more noise gets through to the interior. “We often think glass is the weak link without knowing the real details,” she said.
Acoustical specifications are increasing at an astronomical rate as people seek highly-productive environments and wellness for occupants of commercial applications. Schimmelpenningh also explained that architects have a strong desire for multifunctional offerings.
Acoustical glazing often is specified for use in airports, museums, religious facilities, government facilities, arenas and VIP boxes, opera houses and for building near transportation routes.
Glass thickness is the most basic way to improve the noise control of a façade. Glass with a thickness of 16 mm has a sound transmission class (STC) of 40. Glass that is 1.5 inches thick has an STC of 48 compared to a 4-inch concrete wall with an STC of 40-48.
Insulating spaces and a dampening, soft interlayer also helps mitigate noise pollution.
“Glass is no longer the weak link for acoustics when using modern materials,” she added.
Eric Miller with Intertek focused on acoustical glazing testing.
“How you install a glass panel and test it will affect the kind of result you get,” asked Miller. “Our lab tries to replicate installation of the actual products. We try not to apply too much sealant because it could give elevated ratings and a higher performance than exists in the field. We want to make it as realistic as possible.”
Miller explained that sound takes the path of least resistance, just as electricity does. If a frame system is weak, a higher percentage of sound will go through the frame and drop the system’s performance levels.
“The weakest element governs the performance of the entire system,” he said.
Miller and Schimmelpenningh each addressed the possibility of modeling for acoustical glazing. “It’s getting there. We’ve done a lot of testing and have a good feeling about how it performs,” said Miller.
Both agreed that modeling of the glass itself is possible but the software currently available is not advanced enough to take the entire system details into account.
The best way to achieve success on curved glass projects is for the fabricator to manage the customer’s expectations up front.
“We really try to educate the customers on the front end about what they can expect. We do that with full-scale mockups of the project so there are no surprises,” said Jake Bowser of Standard Bent Glass.
Panelist Javier Sanchez Gil of Cristacurva explained that there are two categories of curved glass: essential and enhanced. Essential curved glass has similar tolerances and size limitations to flat glass.
“Don’t be scared of curved glass,” added panelist Beatriz Fernandez with Cricursa. “It’s more rigid than flat glass. The ratio of deflection is different. If engineered correctly with the right allowances, then everything is okay.”
Fabricators can curve several coating types, but the ability to curve each coating varies from project to project. According to Sanchez Gil, low-E coatings were not available for curved glass five years ago.
“Curved glass gives a great distinctive feature to any architectural feature. The possibility of being able to curve low-E glass has enhanced the architecture and the possibilities,” he said.
Fernandez explained that coatings can be damaged when bent.
“We have to go through mock-ups. There’s no bible for coatings. It depends on the radius or shape. A coating might work on one project but on the next it may not. We have to check project by project,” she said. “The issue we always have is when you have flat and curved areas in the same façade. At the end of the day, the curved glass commands the situation. You have to find a bendable coating, then use the same coating for the flat glass.”
Tempered curved glass only allows for a single radius. Complex curved glazing requires annealed glass.
The panel also addressed their companies’ shipping solutions. Essentially, curved glass is shipped in the same manner that flat glass is shipped, but specialty glass often requires specialized crates, especially in cases where each lite of glass is different.
“We try to make it as easy as possible for the industry to use more curved glass,” said Sanchez Gill.