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As seen in Doors & Hardware, March 2012

Fire-Rated Glazing Proves Life Safety Can Be Green

By Jeff Razwick

According to the US Energy Information Administration, buildings consume 76 percent of power plant-generated electricity in the U.S.1 Since artificial lighting accounts for a sizable portion of this electrical demand, building teams are more frequently incorporating strategies for maximizing daylight capture within their building plans to reduce energy usage and costs. Increasingly, such strategies include fire-rated glazing.

Unlike concrete, masonry and other fire-blocking materials, fire-rated glass allows light to reach deep into interior spaces. More importantly, its unique composition allows it to provide around-the-clock protection against the spread of fire and smoke.

Today, as technological developments continue to give rise to increasingly sophisticated fire-rated glass systems, it is possible for building teams to meet fire ratings and have large expanses of glass, instead of being limited to smaller windows, borrowed lites, and small view panes in doors.


Transparent fire-rated wall panels help illuminate a stairwell in a corporate office.


Fire-rated curtain walls allow light to pass through interior spaces requiring fire separations.


The Emergence of Sophisticated Fire-rated Glass Systems

Modern fire-rated glass systems are sleek, clear and versatile, providing high levels of fire and life safety performance with little or no aesthetic impact on sightlines, views and neighboring glazed applications. These advanced systems are the result of two key technological breakthroughs.

The first pertains to fire-protective glazing – glass that defends against the spread of flames and smoke (compared to fire-resistive glazing, which also blocks heat transfer). Manufacturers now offer fire-protective glazing that is clearer and thinner, with negligible surface imperfections. Such high-clarity glass is beneficial for door assemblies and large sections of borrowed lites, as color and surface imperfections in older products can be visible in applications where viewers may come into close proximity with the glass. Closer resemblances to ordinary float glass helps building professionals provide crisp, clear glazing in areas that necessitate fire-rated materials by code.

Another important development is the growth in fire-resistive glazing options. Manufacturers can now pair fire-resistive glass with narrow-profile, fire-resistive frames. These integrated products can pass the test standards for solid walls, allowing building teams to create glazed areas that extend from floor-to-ceiling, wall-to-wall, and across multiple stories while protecting building occupants and construction from the high heat generated by building fires.

No longer limited to small panes of traditional wired glass, building teams can select from a range of fire-rated glass systems than can now supplement daylighting design, including:


Natural light extends through a museum’s full-lite fire-rated glass doors.


A large fire-rated glass floor system serves as an atrium for belowground spaces.


Daylighting through fire-rated glass floors

Fire-rated glass floor systems can facilitate views and increase daylight while supporting structural loads and blocking flames, smoke and heat.

Transparent in nature, such floors can help maximize light penetration in numerous ways. For example, aligning glazed floors beneath skylights allows natural light to pass down into rooms that otherwise would be cut off from sunlight. Similarly, large glass floors can serve as atriums or light portals for stairwells and belowground spaces.

Another daylighting alternative is to use individual glass floor slabs for borrowed lites in roofs or floors. These small pieces of glass work well in highly trafficked areas, such as corridors, and in gathering areas that require diffuse light.

In areas where modesty is a concern—including where people are directly visible to individuals on lower levels, as well as for rooms beneath glass floors, like conference rooms—obscure top surface glass panels or films can allow light in, while providing privacy.

Daylighting Benefits

The flexibility to incorporate extensive glazing that also meets fire-rating requirements provides many daylighting benefits. A primary advantage is the ability to better maximize light penetration. For instance, building teams can now align expansive fire-rated glass applications in a range of settings to draw light deep into a building’s core. They can place fire-rated glass systems directly in line with non-fire-rated glazing systems; place them above open spaces in interiors, such as multi-story shafts (for more on this, see “Daylighting Through Fire-rated Glass Floors); or incorporate them in typically hard to illuminate spaces such as stairwells. Additional beneficial orientations can include:

Another key challenge modern fire-rated glass systems help overcome is glass size limitations. As discussed previously, fire-resistant glass systems are tested to the same standards as walls, making it possible to use large individual panes or curtain walls to create great expanses of glazing. Here, the benefits are two-fold: Not only can large glazed areas capture more light within building interiors, they can also help building teams earn points towards LEED green building ratings. Specifically, building teams potentially can earn points towards LEED Indoor Environmental Quality (EQ) Credits 8.1 and 8.2, Daylight and Views by providing occupants with access to natural light within 75 percent of regularly occupied spaces, and views to outdoor environments within 90 percent of all regularly occupied areas. For instance, a possible method for earning points in this category is to draw the line of sight or daylight through large, interior expanses of fire-rated glazing, including for private offices, classrooms, and similar spaces.

Modern fire-rated glazing products also can enhance safety in today’s open building designs by dividing them into smaller compartments. The absence of compartmentalization in large, shared spaces provides an opportunity for faster fire growth given the greater air volumes. According to the U.S. National Association of State Fire Marshals (NASFM), open designs can create “a lack of compartmentation that would serve to limit fire spread to a smaller area, such as a room or a wing or a floor of a building.”2 Building teams can use large spans of fire-rated glass to help resolve this dilemma. For instance, a fire-rated glass system that stretches across multiple stories can provide the feel of an open, light-filled space, while helping reduce the area’s overall volume and defending against a fire’s spread.

Keeping Pace

As the need for increased light transfer continues to drive manufacturer development of new glazing systems, architects, specifiers and other building professionals can expect an ever-expanding range of fire-rated glass and framing options, as well. While this means fewer compromises between achieving a desired aesthetic and fire and life safety performance, it also means building teams must stay abreast of the evolving product landscape. Contact a manufacturer or supplier to learn about the latest offerings and any resources they offer.

Notes
1“The Building Sector: A Hidden Culprit.” Architecture 2030. Santa Fe, N.M.
2 See Jim Tidwell and Jack Murphy’s “Bridging the Gap: Fire Safety and Green Buildings” (National Association of State Fire Marshals, 2010), available at greenbuildingfiresafety.org/PDF/NASFM_greenfire_guide.pdf.

Author Information

Jeff Razwick is vice president of business development for Technical Glass Products (TGP), a supplier of fire-rated glass and framing systems and specialty architectural glazing. He writes frequently about the design and specification of glazing systems for institutional and commercial buildings, and chairs the Glass Association of North America’s (GANA’s) Fire-rated Glazing Council (FRGC). www.fireglass.com, (800) 426-0279

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