Photoluminescent Exit Signs: The Electricity-free, Non-radioactive, No-maintenance Alternative To LED Exit Signs
Introduction
AfterGlow® is a brand name for a range of photoluminescent (PL) - non-electrical, non-radioactive, glow-in-the-dark products used in buildings to provide a safety marking system throughout the structures. DHi's® (Defense Holdings, Inc.®) AfterGlow® Brand products include entrance, exit signs and other signage, tapes and paints, and UL Approved EXIT signs that provide lighting without electricity, batteries, LED’s or radioactive materials, Figure 1.
PL products are sustainable, LEED certified and can earn LEED credits points for building owners in green building design and construction. They can be used to retrofit existing buildings, are ideal for historical preservation, and can be used to significantly reduce the energy budget and electrical infrastructure for new construction. Installation costs are very low, they require fewer building materials to make, are maintenance free, and consume ZERO energy because they are charged by ambient light, Figure 2.
Figure 2. Actual Installation of UL 924 Approved EXIT Signs in the Eisenhower Executive Office Building
PL products are effective and, in many emergency cases, superior to other methods. PL products continue working long after emergency generators typically stop running and their luminance far exceeds that of many LED products.
Background--Building Codes and Requirements
To protect the health, welfare and safety of communities, the building industry adopts international building and fire codes and standards which are applied to every aspect of building design and maintenance. Codes are revised every three years to make changes so that these standards include the latest in innovation, technology, and approaches to health and safety. Virtually every building, process, service, design and installation in the industry today is affected by these international standards, and in the U.S., they are also affected by the National Fire Protection Association (NFPA) standards. These codes were all revised in 2009 to state that “luminous (visible) egress path markings shall be required in all new and existing buildings—institutional, educational, business, hotel, public assembly and residential,” that meet specific occupancy and location requirements. This means that all doors, rails, steps, landings, perimeters and obstacles have to be able to be seen and clearly designated. This is a legally-mandated requirement for all building owners. In addition to meeting this legal requirement, having common lighting/visibility in these areas helps guide occupants through them safely. This requirement also provides additional protection for an aging population that sees less clearly, creates a common, non-verbal communication designating exits, entrances, and related areas for a multi-lingual population, and more importantly it matters in emergency situations such as fire or long-term electricity blackouts that leave people stranded. Figure 3 shows an actual installation demonstrating a typical installation required in accordance with this legally-mandated requirement.
Figure 3. Actual Installation Using PL Tapes and Building Safety Paints certified by NYC DOB
How Photoluminescent (PL) Technology Works
PL materials (also known as "glow-in-the-dark" materials) incorporate inorganic phosphors into a carrier or substrate. The substrate might be a solvent-based or water-based paint, a magnetic- or adhesive-backed tape, a plastic extrusion, an acrylic or polyurethane casting or injection molded item, or a vinyl film. These PL phosphors absorb light in the visible and ultraviolet wavelengths and release visible light in what is often termed an “afterglow.” This afterglow luminance decays over time. The “Extinction Time” is the time for the luminous intensity of the afterglow to decline to the lower luminance limit of human perception for dark-adapted eyes (0.032 mcd/m²). More important is the “Functional Time.” For AfterGlow® brand products sold by DHi, the minimum Functional Time is 8 hours, providing more than enough light for everyone to exit. For example, the NYC Department of Buildings (DOB) has determined the minimum brightness rating shall be 30.0 mcd/m2, 7.0 mcd/m2, and 5.0 mcd/m2 at 30-60-90 minutes after a loss of lighting. Dark adaptation of the viewers’ eyes results in a perceived brightening of the material. In all cases, the critical performance characteristics are the Luminance Performance (i.e., the brightness of the material and how long it will glow). Photoluminescent materials will continue to perform even if damaged. Unlike the “Novelty-grade” PL materials often used for glowing Halloween skeletons or stars on the ceilings of children’s bedrooms, the “Safety-grade” PL materials will not lose their ability to hold a charge. Modern Safety-grade phosphors can be recharged time and again for many, many years.
AfterGlow® in Action
In 2001 after the World Trade Center was attacked, experts who analyzed the consequences of the event highlighted the need to use new technologies like Safety-grade PL products, so that people could see the exits, stairs, floors and doors to escape. In this situation of extreme fire and smoke it was difficult for people to figure out where the exits, windows, doors and stairs were. Following the Northeast Blackout of 2003 that occurred throughout parts of the Northeastern and Midwestern United States and Ontario, Canada, the City of New York (NYC) passed rigorous new standards, Local Law 26/04, which requires PL Egress Marking Systems in certain commercial buildings to guarantee a safe exit in the event of a major disruption or disaster resulting in a loss of lighting or reduced visibility. AfterGlow® products have been used in over 150 government and commercial buildings in NY because they meet and exceed the requirements of this law.
Similarly, when the plane crashed into the Pentagon that same day in 2001, both primary and secondary power sources immediately stopped working making it very dark in parts of the building, clouding escape routes. Analysts recommended improved safety measures in renovating the Pentagon using AfterGlow® products. DHi’s PL products are now used for all entrance and exit signs, PL tape is used to mark the corridors, floors, stairs, windows and doors so that exit paths can be seen in complete darkness or when smoke obscures traditional exit markings. The use of PL products was considered so essential for safety, that they were installed not only throughout the newly renovated portion of the Pentagon but also retrofitted into older sections of the building, even though total renovation would take another 8 years.
In the recent years, major regions of the northeastern U.S. and Canada have experienced 18 hour blackouts and brownouts. In this case, electrical systems, both primary and secondary (backup or generators) failed; many just ran out of fuel. Other
systems failed because of improper or neglected maintenance. Even today most buildings and facilities have insufficient emergency lighting even though they meet the requirements of local and federal codes. PL lighting and markings are a good low cost, low maintenance solution for all buildings. Figure 4 shows a sampling of locations for DHi’s products.
Figure 4. Lights On/Lights Off Photographs of Actual AfterGlow® PL Installation
President’s Executive Order
In October 2009, President Obama signed in an Executive Order, establishing an integrated approach to sustainability, which includes making green house gas (GHG) reductions a priority for federal agencies. He hopes to reduce overall GHG contributions by 28 percent by 2020. GHG reductions can be made by reducing energy use, and switching to PL products can help federal building owners and managers reach these goals sooner.
Environmental Protection Agency (EPA) U.S. Climate Leaders Program
DHi® (Defense Holdings, Inc.®) is one of 60 small businesses joining the EPA’s U.S. Climate Leaders Program. The purpose of the program, which is also sponsored by the General Services Administration (GSA) Small Business Program, is to have the companies commit to measuring and reducing their green house gas (GHG) emissions by at least 5 percent within 5 years. They also have to maintain carbon neutrality for at least 3 years after setting a base year.
The advantage this brings to users of AfterGlow® products is that users are buying a green product and the user can include this in their carbon calculation to offset their company’s carbon contribution. This is critical for companies that sell to the federal government because GSA and all federal agencies are going to start requiring companies to calculate their GHG contributions, and GHG will become a factor in awarding federal contracts. Companies using AfterGlow® safety marking systems will have a competitive advantage.
DHi in Defense and Homeland Security
DHi’s PL paint is being used by the Navy to make spinning propellers visible to ground crew on dark aircraft carrier flight decks. More than 15,000 PL emergency egress lighting kits have been sold for use in combat and tactical vehicles. PL instrument panel lighting is being used on Border Patrol helicopters; other DHi PL safety marking products are in use on Navy and Coast Guard ships.
About DHi
Since 2001 DHi has been a leader in all the areas of high performance photoluminescent technology (PL) industry including research, specifications development and manufacturing. The company is a privately-held, service-disabled, veteran-owned, minority small business that works with customers to develop comprehensive PL safety solutions for buildings. DHi employs 26 people and is based in Arlington Virginia with other facilities in Charlottesville, VA and Trenton, NC. DHi has been ISO 9001 registered since 2003. DHi has received awards from the federal government for outstanding technical innovation and performance.
