Fenestration: Fire-Rated Glazing & Daylighting

Designing To Maximize Daylight Transfer

by Devin Bowman, general manager, Technical Glass Products & AD Systems

Increasingly known as the Indoor Generation, it is no secret that today many people spend more time inside than out.  Underscoring this shift, a survey sponsored by the Environmental Protection Agency (EPA) reports that Americans spend on average approximately 87% of their time in enclosed buildings, with 69% of that time spent at home and the remaining 18% spent in other venues like workplaces. 

         Given the alarming estimated amount of time spent indoors, the design community has placed greater emphasis on creating buildings centered on the needs of their occupants.  While there are many facets of building design that affect the success of this outcome, one that holds great weight is access to daylight.  Studies continue to identify a positive link between access to natural light and improved occupant well-being, from better patient outcomes to enhanced worker productivity. 

         To reap the benefits of daylighting, building teams employ numerous strategies ranging from skylights and expansive curtain walls to circulation hubs oriented to allow light to easily transfer between interior spaces.  Unfortunately, many of these tactics fall by the wayside in building areas where it is necessary to comply with stringent fire-safety and life-safety standards.  The sub-division of spaces via fire-rated building materials, also known as compartmentalization, is critical to slowing or stopping the spread of flames and smoke in a fire event.  However, traditional fire-rated building materials like concrete and gypsum block light transfer and views.

         To help resolve this dilemma and improve occupant welfare, more building teams are turning to fire-rated glazing in commercial building design.  Once synonymous with traditional wired glass, fire-rated glazing products have evolved to combine a transparent form with the ability to withstand temperatures up to 1600º F or greater.

Why Fire-Rated Glazing?

         Today’s fire-rated glazing products provide the same defense against fire as traditional fire-rated materials while also preserving daylight transfer.  Fire-protective glass is generally suitable for use in opening-protective applications.  This includes transoms, borrowed lites, and doors.  In application, it can help building teams maximize light transfer and views by allowing openings in corridors, exits, stairwells, classrooms, and other areas of egress.  Fire-protective glass can also enhance safety and security when used in doors and sidelites, as it offers greater visibility for people entering and exiting rooms.

         Fire-resistive glass is subject to the stringent fire-resistance test standards for walls.  As such, it can exceed the traditional size parameters of fire-protective openings, enabling use in locations where the total glazing area exceeds 25% of the wall.  Instead of being limited to smaller windows and view panes in doors, building teams can now have large expanses of glass meeting some of the most stringent fire-rated building codes. 

         From fire-rated glass curtain walls to fire-rated glass floor systems, these sophisticated assemblies help draw daylight deep into interior spaces formerly restricted by concrete or gypsum.  The outcome is light-filled, porous and code-compliant areas more conducive to occupant well-being. 

Maximizing Daylighting Within Code

         To best maximize light transfer, design teams can strategically align expansive fire-rated glass systems within a building.  Examples include installation in typically hard-to-illuminate spaces like corridors and stairwells or in line with non-fire-rated glazing systems.  In buildings where perimeter glazing is limited, fire-rated glass floor systems are rising to the challenge.  Not only do these load-bearing systems satisfy codes requiring a fire barrier between floors, but when aligned beneath skylights or atriums, they allow natural light to pass down into rooms that otherwise would be cut off from sunlight. 

         In looking beyond new builds, fire-rated glazing can help restore light transfer in renovations.  Many existing structures rely on traditional, opaque fire-rated building materials to provide fire protection.  By using fire-rated glass to change these solid walls into clear ones, design teams can open up light-restricted areas while bringing buildings up to code compliance.

A Bright Future

         Given the dual need for compartmentalization and transparency to help promote occupant well-being, use of fire-rated glazing will only likely grow.  This means building teams must stay abreast of the evolving product landscape.  Contact a manufacturer or supplier to learn about the latest offerings and resources as the industry works to bridge the gap between these two important needs. 

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