Prior to the 1993 World Trade Center bombing, most U.S. commercial and residential R1 buildings used backup lighting to illuminate their vertical exit enclosures during low visibility evacuations. But when bombs destroyed the World trade Center’s back up generators that powered its backup lighting, leaving evacuees in the dark, the nation took notice. Over the next ten years, most states adopted a version of the International Fire Code (IFC), a code created by the International Code Council (ICC) to regulate egress safety in commercial and residential buildings that contain occupancy above 75 feet from the lowest level of fire vehicle access.
From proper construction to safety signage, the IFC regulates all aspects of egress safety. But its most mentioned application has dealt with vertical exit enclosures concerning luminous evacuation egress systems, which feature two basic implements: IFC approved exit signs (a.k.a. running man signs), floor identification signs, and egress markings, with the markings usually applied in tape form. Immediately, luminescent signs and markings seem to have three advantages over back up lights: greater cost effectiveness, greater reliability, and greater evacuation efficiency. Below, we examine these potential benefits to see if they make sense.
Greater Cost Effectiveness
If you’re constructing a new building, implementing luminescent markings will cost less than implementing emergency lighting. But what if your building already contains emergency lights? If it does, the issue becomes whether it’s less expensive to maintain than the markings are to implement. Following its implementation, maintenance-free luminescent tape won’t cost you anything. In fact, it never degrades unless placed in sunlight. That means that maintenance for backup lighting makes it more expensive in the long run than applying luminescent tape.
As the 1993 bombing of the World trade Center displayed, backup lights can indeed fail. Yet, in most instances, it responds as expected. Does that mean that applying glow in the dark egress stripes and signs isn’t as important as companies that sell such products say it is? Not really. While emergency lamps seldom fail, they always offer poor illumination in the presence of smoke, with their incandescence or LED light reflecting off smoke particles instead of illuminating an enclosure.
According to a 2010 study by researchers at the National Institute of Standards and Technology (NIST), the behavior of evacuees is perhaps the greatest determinant of how smoothly and expedient an evacuation is, a finding that places more importance of how evacuees respond to exit environments than conceptual metrics for evacuation flow. Because luminescent markings and safety signs fully and reliably reveal the dimensions and exit-leading doors within exit stairwells, they create more confident, clam evacuees, helping to ensure that evacuations are efficient, expedient, and without casualties or serious injuries.