In Case of Emergency, Show Occupants the Door

Building Operating Management, Mar 2005 by Windle, Lynn Proctor

PHOTOLUMINESCENT SIGNS AND MARKINGS glow in the dark, without electricity, to provide a reliable path to the exit

When the electricity goes out and a building must be evacuated, photoluminescent technology could be the guiding light that leads tenants to safety. Used for years in passenger aircraft, marine and other transportation applications, photoluminescent technology has moved into the facility arena in the past few years. Powered only by ambient light, photoluminescent safety signs and path markers glow in the dark similar to children's novelty decals found at any craft store but at a much higher level.

"The purpose of photoluminescent technology is not the illumination of a space," says Jim Amy, senior consultant with Rolf Jensen & Associates. "The purpose is to provide definition of a space so people can orient themselves. Photoluminescent material marks the leading edge of the steps. It marks the landing, and it marks the handrails. Your mind kind of fills in the blanks so you can orient yourself. It's like cutting off the bottom of a word. You can't see all of it, but you know what's supposed to be there."

Phoioluminescent technology offers advantages over electrically wired exit signs and emergency lighting. One is reliability. Because the glow is a chemical reaction, an adequately charged sign will not fail.

"It is 100 percent reliable," Amy says. "You can't stop it from performing if it is charged. And it is being charged by lighting that would normally be on anyway. You're not depending on electrically powered systems during an emergency, and you're not depending on a charged battery."

It also saves energy. Charged by existing light, photoluminescent technology is the first ENERGY STAR program with zero energy consumption, says Al Carlson, chairman of the International Photoluminescent Safety Product Council and vice president of Jessup Manufacturing.

NEW YORK CITY CODE

Its high reliability factor is the main reason New York City has established a new city ordinance requiring all buildings over 75 feet tall to install photoluminescent safety systems.

Local Law 26 of 2004, passed last fall, requires that photoluminescent signs be installed on doors leading to exits and photoluminescent markings be installed in exit stairs, says Michael Rzeznik, manager of Schirmer Engineering's New York office.

Rzeznik says the changes were the result of recommendations by the city's World Trade Center Building Code Task Force. Among other things, the task force reviewed operating requirements and determined what modifications were needed in new and existing buildings to ensure public safety during extreme events. The recommendation for photoluminescenl technology stemmed in part from failure of emergency battery-powered backup lighting during the first bombing of the World Trade Center in 1993.

The new law says that photoluminescent systems must be in place by July 2006. The measure applies to all high-rise buildings regardless of when they were built, Rzeznik says.

Regulations that will implement the new law are currently being developed, says Geoffrey Peckham, president of Jalite USA and a member of the task force looking into implementation standards. Among the issues involved are the configuration of photoluminescent components - where they should appear and what they should look like - and the physical properties of the photoluminescent materials.

Though photoluminescent safety markings are similar in concept to glow-in-the-dark decals, experts say there is a significant performance difference between commercial-grade and novelty-grade material.

Commercial-grade phosphorus holds energy for hours, though a majority is given off in the first 10 minutes. "The luminance may decrease, but it does so as your eyes are adapting to the darkness, compensating for the dimming of the sign in the first 40 or so minutes," Amy says.

Strontium oxide aluminate, a pigment introduced in 1995, has vastly improved product quality. The pigment can be contained in materials like ceramic, plastic, tape and even paint. The strength of the material's charge depends on three things: the type of available light, the intensity of the light, and how long the light is on, Amy says.

Fluorescent and halogen lights charge the material better than incandescent light. Sunlight charges the material well but causes deterioration over time.

Photoluminescent markers should be placed near or on the floor. Because smoke rises, positioning the markers close to or on the floor allows occupants to find their way even if they must exit on hands and knees. On the floor, the exit path should be illuminated with a continuous piece of material, says Amy. On the wall, it should be continuous except as the exit path is interrupted by doors.

'THIS STUFF GLOWS'

The amount of material used depends on how much available light is present and how much afterglow is expected. If the passageway is 2 meters (6.5 feet) or more wide, the material should be placed on both walls.

A study by the Institute for Research in Construction, part of Canada's National Research Council, showed that occupants who were not familiar with stairwell conditions could evacuate a stairwell marked by photoluminescent wayfinding systems as quickly as counterparts could in a fully lighted stairwell.