How Do Photoluminescent Exit Signs Work and Why Are They Valuable?

Photoluminescence is a complex word that describes a rather simple phenomenon - a product's ability to produce light without the aid of commercial power sources such as electricity and batteries. In scientific terms, this phenomenon occurs when an object absorbs photons from ambient light and then re-emits the photons in darkened surroundings, creating a lighting effect that ranges from ambent to bright depending on the object's absorption ability. From a quantum mechanics viewpoint, the object moves from a high energy state to a low energy state, re-emitting the photons until it loses its light.

These objects are often called "self-sustaining" because they produce their own energy, a perfect example of which can be found in the most commercially popular of all such products - photoluminescent exit signs.

Companies that are committed to going green and saving money have popularized these safety signs in the corporate sector. The exit signs play a role in the U.S. General Services Administration's plan for sustainable design principles, which seeks to minimize non-renewable energy consumption. The signs are also a part of Victoria, Australia's Department of Sustainability and Environment's plan to pursue environmentally friendly urban construction. In addition to preserving non-renewable energy, the signs are bright, recyclable, non-toxic and, unlike traditional safety signs, non-radioactive.

The significance of the exit signs to companies that are going green is obvious, but even for companies that have yet to go green, switching from incandescent safety signs to signs that are more energy efficient reduces operating costs. Incandescent exit signs burn 24 hours a day, 365 days a year. Add in the cost of replacing light bulbs, back-up batteries and repairing faulty wiring and, for a large corporation, and the cost difference can amount to thousands of dollars a year. In addition to being maintenance free, the safety signs have an average life span of 25 years.

In trimming power usage and maintenance costs, tritium, compact fluorescent and LED exit signs are also cost effective solutions to incandescent safety signs, but the last two are not maintenance free and all three have a shorter life span than photoluminescent signs. The average lifespan for tritium exit signs is 10-20 years, while the life span of LED and compact fluorescent signs is roughly eleven years and roughly six years, respectively. Photoluminescent signs are also easy to move if egress paths change, whereas LED and compact fluorescent signs require re-wiring. Compared to the competition, the exit signs are the soundest long-term environmental and monetary investment.

According to a popular photoluminescent safety sign company, the ten-year operating cost for one if its exit signs, including labor and installation, is $111.00. Comparatively, the ten-year operating cost of a tritium exit sign is estimated at $190.00, while the ten-year operating cost for individual LED, compact fluorescent and incandescent exit signs rises to $370.00, $894.00 and $1,465.00, respectively.

Most companies that sell photoluminescent safety signs sell other self-sustaining signage as well, including fire hose and fire extinguisher signs, stairwell signs, direction arrows and photoluminescent marking tape for identifying pathways in darkened surroundings.