Volume 39, Issue 9,
Playing it Safe
Emergency Egress Through Laminated Glazing
by Mark Gold
Building codes often require, and/or modern architectural designs specify, glazing materials that provide enhanced performance levels of security and safety. These performance properties include: resistance to ballistics, blasts, hurricane/cyclic wind pressures and physical attack. Glazing applications may also specify such properties as sound reduction, fade resistance and solar and thermal control. Because laminated glazing materials are able to meet such codes and design criteria, they are finding application in a broader range of installations than ever before. The use of laminated glazing in residential and commercial installations has led to inquiries by design professionals and specifiers regarding the reaction of public safety officials to these products.
Laminated Glazing Fabrication
Laminated glazing materials consist of multiple layers of glass, interlayers, resins and/or plastic glazing materials that are often complex in nature. The interlayers can be any one of several thermoplastic layers such as polyvinyl butyral, polyurethane or other individual or combinations of thermoplastic polymers. These layers usually are bonded to the glazing system base (glass, acrylic, polycarbonate, etc.) using heat and/or pressure systems that create a glazing lite. Laminated glazing can also be fabricated using cured resins between the layers of glass. In each construction, the resulting glazing product is designed to provide the specified level of performance for the required application.
Laminated glazing materials have performance properties that add value to architectural structures, automobiles and aircrafts. In addition to reducing solar gain for energy control and sound transmittance in acoustically engineered structures efficiently, laminated glass provides a barrier to penetration. This transparent, yet resistant, glazing system helps protect against a range of man-made and naturally occurring situations that would cause the structural envelope to be breached if laminated glass was not used. Such situations include security requirements to protect against forced-entry, ballistic- or even blast-attack. Laminated glazing provides protection and safety in naturally occurring situations such as earthquakes, windstorms or hurricanes. In such situations laminated glazing tends to remain in place if broken, thereby reducing the likelihood of glass-related injury.
A frequent question regarding the installation of laminated glazing systems concerns how the glazing will affect the ability of an occupant to use the window as an emergency egress. In residential applications, doors are utilized for emergency egress and, in those instances where windows are used for egress, the windows can be opened using the standard locking/latching mechanism prior to egress. If a resident must leave a burning building through a window, typically he opens the window to escape.
“Normally, it is not somebody’s first response to break a window,” said Mike Forgy of the International Association of Fire Chiefs.
In office buildings, the installation of laminated glazing in non-operable windows would not affect their use for points of egress since these windows usually are installed in multi-level (high-rise) buildings where such windows are not the designated point of egress. According to Reginald Penny, president of the Fire Marshall’s Association of North America and chief and district commander for the Palm Beach County Fire Department, “Windows are only to be used as a secondary means of escape according to standard building code requirements.”
Often of greater concern than the issue of emergency egress is the perceived deterrence that laminated glazings pose to fire and rescue personnel attempting to enter a building. “We really don’t like to break windows because the sharp glass shards that remain can cause injury and cut through fire hoses,” Penny said. “Windows are removed as a last resort because there is too much room for error and injury.” According to Penny, the ability of laminated glazing to resist penetration does not pose a significant risk to inhabitants during a fire. “We use windows as a last resort in rescue operations because open windows feed oxygen to a fire and often times when utilized, windows do more harm than good because they have a tendency to blow out when punctured under pressure,” said Penny.
In some severe cases, though, it may be necessary for a firefighter to enter through a window. With the implementation of building codes that have made laminated glazings more prevalent, fire and rescue personnel are being targeted for awareness of, and response training toward, these products. GANA is aware of several training programs, which instruct fire and rescue personnel to quickly identify the presence of, and respond to, penetration deterrent glazings. Fire and rescue personnel are equipped to penetrate these glazings with the available tools they bring with them in an emergency situation.
Government and Industry Research
Federal and local governments have reacted to concerns about emergency access through laminated glazing materials. The U.S. General Services Administration (GSA) in conjunction with the Office of Homeland Security commissioned a study by Hinman Consulting Engineers in May 2003, that tested emergency personnel access through penetration deterrent windows (such as those specified for blast-resistant glazings in GSA facilities).
Working with the San Jose (Calif.) Fire Department and the Protective Glazing Council, 27 different protective glazing constructions were studied, ranging from standard glass to blast-resistant glazing. Fire and rescue personnel utilized the standard forcible entry tools and operating procedures of the San Jose Fire Department and the International Fire Service Training Association. As stated in the report’s conclusions, “The firefighters were able to enter all of the window mock-ups with conventional firefighting tools such as axes, hooligans’ tools and pike poles. Though conventional tools were equal to the job, updated techniques were required to efficiently break and clear the windows.” The complete study, along with videos of the entry tests, can be found on the Internet site of the Office of the Chief Architect of the GSA at http://www.oca.gsa.gov/specialphp/References.php.
Additional comments from this report are:
“All tools used in the tests are commonly carried on fire apparatus or by firefighters throughout the United States. Entry was restricted to gaining access through the glass itself and not by prying the window framing from the wall. If the firefighters did not gain access with these limitations, provisions were made for the use of more sophisticated tools. In this set of demonstrations, more sophisticated tools were not required.”
“Films and lamination tend to hold glass shards together, which can allow firefighters to move the glass away from the operational area easily and may decrease the likelihood of injuries associated with stepping on glass shards (slip, trip and fall type injuries). It can also reduce the hazard from falling glass to those working outside the building.”
Like the U.S. Government, private industry is also working to inform and educate emergency rescue personnel. Manufacturers of penetration-deterrent windows have conducted training demonstrations and produced educational videotapes that they make available to fire and rescue personnel. In one such demonstration, using windows supplied by a local manufacturer, the Sarasota, Fla., Fire Department produced a video that shows the effective means of breaching hurricane building code compliant windows using tools ranging from the pick head ax and Denver tool to powered reciprocating and rotary saws.
Among its conclusions, the Hinman report suggests that “The transfer of information on [these] window systems should be made a priority by entities involved in the installation of these window systems … To assist local fire departments in assessing the demands on their operations … the following information should be offered:
• A summary paper of this report;
• Five-minute video, showing highlights of the demonstrations; and
• Full-length video, showing all demonstrations.
For additional information on laminated glazing materials consult the GANA Laminated Glazing Reference Manual and the GANA website: www.glasswebsite.com.
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