Acoustical Glazing is Becoming Increasingly Important. Here’s What You Need to Know.

By Ellen Rogers

When it comes to architectural design, most everyone wants two key things: a building that looks good and is energy efficient. Thanks to plenty of innovative glazing products, that’s fairly simple to achieve. Plus, architects, engineers and contract glaziers are increasingly working with cutting edge software and design programs, helping to make these out-of-the-box ideas a reality.

In many cases, buildings—and in particular, their facades—are moving a step beyond looks and energy performance. For many applications, sound control is becoming an increasingly important focus. For example, New York City’s Office of Environmental Coordination’s City Environmental Quality Review Technical Manual includes a chapter specifically focused on noise. The manual addresses noise as it relates to regulations and guidelines that govern activities in the city. It also defines technical terms, discusses
the appropriateness of a noise analysis, and provides information related to detailed noise analyses, study area definitions, technical subareas, models and analysis techniques.

The Big Apple is not alone. Many major metropolitan areas are also starting to mandate sound control in various building projects where noise pollution may be a concern.

What’s this have to do with glass? Just as with energy performance, glazing is the weakest link in sound control when compared to other building products. Fortunately the industry is addressing this concern, ensuring glazing products maintain their prominent façade placement.

Driving Forces

In today’s architectural and construction environment, the wants and needs of owners and developers is becoming increasingly complex. There’s more to designing and building structures and facades than just looks and thermal performance. In urban areas in particular, concerns about environmental noise pollution have escalated, given growth in high-rise residential construction. Now, acoustic requirements are becoming increasingly important to the building envelope.

Casey Mahon, president and CEO of St. Cloud Window Inc. in Sauk Rapids, Minn., says one of the biggest drivers behind this shift is a focus on improved quality of life.

“We live in a noisy world where people are frazzled with the pace of life and they want to be somewhere they can find some refuge,” he says. “[Acoustics] is the last green frontier for what makes us live and work better.”

Acoustical glazing is commonly used in hospitality or residential projects located in particularly noisy areas. These include those located near airports or even elevated trains.

“Over the last 15 years it has been residential and hotel towers, as well as hospitals, in urban environments that seek the greatest sound control measures,” says Jeff Vaglio, vice president of Egan, Minn.-based Enclos’ Advanced Technology Center. “For us, those are some of our primary markets: LA, San Diego, San Francisco, Las Vegas, Seattle, New York, Philadelphia and Washington, D.C. During that time, insulating glass units (IGU) have advanced significantly, and the expectations—related to comfort and performance—of the façade assembly continue to increase.”

According to Tejav DeGanyar, director of Schüco’s virtual construction lab in New York, much of the focus has been on requirements coming from the multi-family construction/condominiums being built in these metropolitan areas.

“Some of these are in high- and mid-rise buildings and this has increasingly added to the focus on acoustic performance of the facades,” says DeGanyar. “And, there are some environmental regulations coming in cities like New York that have strict guidelines on what is needed to be operational for of the occupants.”

DeGanyar says this is happening in many metro areas, in addition to New York. For example, Los Angeles is undergoing a major redevelopment and acoustical performance has become more important. He says some developers have also been able to use this concept to drive a higher price for the units.

“They are using the rating of the window as a selling point of the unit so it’s an economic driver as well,” he adds.

Why Glazing Matters

Glass has an important role to play when it comes to acoustical performance. Just as single pane glass alone doesn’t offer impressive energy performance, it’s a similar case for sound control. Companies that have worked to prove the energy-performance benefits of properly designed and specified glass, have done the same for acoustics.

“The marketplace has not devalued the importance of transparency and views while increasing thermal expectations of the building skin,” says Vaglio. “As a result, the glass industry, from IGU compositions to framing mitigation strategies, have adapted. Occupant comfort is a blend of many environmental considerations including acoustics, thermal, daylight, access to ventilation, glare, etc., and though acoustics and glazing may find themselves at odds in a stand-alone evaluation, they are both essential as part of the greater whole.”

As Mahon explains, when you cut holes for windows in an otherwise acoustically-tight wall you open the building up to noise intrusion.

“We’re in Minnesota, and our buildings have thick walls (to protect us from the elements) and then we cut holes in them so we can see out. That’s the weak link,” he says. “You can develop attenuation in the ways you construct walls; so, too, you must get the window to perform as well as the wall because interior noise level is only as good as the weakest link.”

DeGanyar agrees.

“Of all the façade products, the glazing is the weakest for acoustic performance. It’s also a factor when designing a new aluminum and glass high rise, because neither are the best sound-deadening materials.”

And speaking of the acoustical requirements in Europe, he points out another concern that is being addressed: ventilation.

“Now there are enforcements on buildings not only for when the window is closed but also when it’s open, which puts restrictions on how much noise can come through.”

Improving Performance

In response, Schüco has been working on both passive and active products to meet this demand. For example, the company’s AWS 90 AC.SI sound reduction window is designed to offer sound reduction and natural ventilation in the tilted position. It does so by means of a specially developed center gasket and guidance of fresh air through the vent frame, which dissipates sound and reduces noise pollution.

Another product being developed is the Active Noise Cancelling (ANC) ventilation modules. With these, loudspeakers and microphones are installed in the ventilation channel of the ANC ventilation module. The exerted noise level is recorded by the microphones, and the loudspeakers instantly generate a corresponding counter-noise for this noise level. These two sound waves interfere with each other destructively, which means that the noise and counter-noise mix, reducing the overall noise level.

To achieve acoustical performance in the glazing, one major performance benefit is the use of laminated glass. There’s also increasing attention given other components.

“To improve performance of the IGU it’s common to introduce a laminated inboard lite, often unbalanced with two varying thicknesses of panes,” says Vaglio. “Increasingly, consideration of triple-glazing is entertained, as well as deeper air spaces between the lites.”

DeGanyar agrees that triple glazing can be even more effective than laminated glass by itself.

“But the concern isn’t just the glass. It’s also the framing. If you put weak aluminum around it, that diminishes the performance you gained from a good glass. They need to balance each other,” he says. “You need a framing system that matches the performance of the glass. A lot of times the specification only specifies the performance of the glass. So when you add the framing element the result is not as originally anticipated. Those things in the past have not been balanced well. Products are now coming into the market to improve the framing.”

Still Listening?

As acoustical glazing becomes increasingly important to the performance of architectural facades, it will bring a number of challenges. Mahon says that, as more and more architects begin designing with acoustics in mind, there will be a steep learning curve
covering everything involved.

“Most glass manufacturers are very proactive in testing the sound attenuation of their products, but it’s important to remember that the data published is purely the performance of that glass,” he says. “I think the biggest mistake specifiers make is that they rely on just the performance value of the glass to determine whether the fenestration works for their needs. But unless the entire specimen is tested you can’t make informed decisions on whether it meets your needs.”

The glazing industry is educating and increasing awareness on how to design and build an energy-efficient building with high levels of thermal performance. As requirements continue to mandate increasingly stringent acoustic performance, the industry will again be called on to provide the knowledge and information to keep its place on the façade.

Ellen Rogers is the editor of USGlass magazine. Follow her on Twitter @USGlass and like USGlass on Facebook to receive updates.

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