Post 9/11, A Look at Changes in Protective Glazing Design and Production
May 2, 2011
Nearly ten years ago on September 11, 2001, the United States fell victim to a tragic terrorist attack that took down all 110 floors of New York City’s World Trade Center’s twin towers, as well as a section of the Pentagon in Washington, D.C. The World Trade Center complex was comprised of seven buildings, and its twin towers alone contained 200,000 tons of steel and 43,600 windows for a total of 14 acres of glass. The announcement of the death of Osama bin Laden last night led many to contemplate the changes that took place in the United States as a result of his actions.
Just as the world post 9/11 is a very different place, so, too, are the ways in which buildings are designed and built. In particular, the awareness and understanding of glazing materials has increased substantially.
“Since 9/11 the glass and protective window/protective fenestration industry have significantly advanced the quality and performance of extreme load and ballistic resistant products. Key to this has been the development of protective product systems that also provide energy efficiency in architecturally acceptable packages,” says Joseph L. Smith, PSP, principal engineer, director and senior vice president of Applied Research Associates, an international engineering and research company. “Physical testing coupled with more advanced high fidelity analytic modeling has allowed for the use of lighter more efficient and cost effective design solutions. The U.S. Government criteria that drive these requirements (principally the ISC and UFC criteria) are currently being updated and future versions are expected soon.”
Julia Schimmelpenningh, global applications manager, Advanced Interlayers, a division of Solutia Inc., agrees that when safety glazing is needed, architects, designers and building owners are now looking for bundled performance options, “meaning safety and security as well as energy and sound control,” she says. “This is being delivered by strengthened glass, laminated glazings and filmed applications. As the awareness has grown over the decade, the products have evolved with options to meet most needs. It's the willingness to incorporate these options at the build, making them part of the initial performance requirements and building use concepts that have changed most,” she adds.
Valerie Block, senior marketing specialist with DuPont Glass Laminating Solutions, notes that while building codes have not adopted security glazing requirements that address terrorism, architects on government and many high profile commercial projects have included blast requirements in their architectural specifications.
“This has prompted manufacturers to test and market blast-resistant doors, windows, storefront and curtainwall systems that incorporate laminated glass,” says Block. “Last year we sponsored several rounds of shock tube and arena testing to evaluate glazing systems made with PVB and ionoplast interlayers. Both interlayers are effective in reducing flying glass fragments, a potential cause of injury after a blast event."
Mike Sebold, business leader, Building Envelope Solutions, with Tremco Inc., says it’s always good to see the industry not only adapting to new codes and design challenges but exceeding the desired outcome and setting new standards for our industry, out-pacing code officials and federal regulations.
“I am also very pleased with how our industry has encouraged glass and glazing products [to become] materials of choice for designers by demonstrating [product] performance in these challenging applications,” says Sebold.