Feature Article

The Evolution of Exit Signs (and Why the Latest is a Bad Idea)

Edge-lit signs, like the Symmetry model from Chloride Systems, of Burgaw, North Carolina, use LEDs hidden from view to provide uniform illumination of the sign.

Photo: Chloride Systems, Inc.
Exit signs are an important safety component in public buildings. Required by code to clearly identify exits at all times, day or night, these signs can use a lot of energy. Different technologies to reduce that consumption represent a fascinating nexus of environmental building considerations.

For starters, tens of millions of exit signs in North America still operate 24/7 with two 20-watt incandescent lamps. Each of these exit signs can use almost as much electricity on an annual basis (350 kilowatt-hours) as the most efficient refrigerator. Nationwide, the U.S. Environmental Protection Agency (EPA) estimates that exit signs in commercial buildings use 30–35 billion kilowatt-hours (kWh) of electricity per year. That’s the output of five or six 1000-MW coal-fired power plants, and it represents an annual cost on the order of $2–3 billion per year.

The evolution of exit sign technologies over the past several decades is a story of new technologies that have dramatically reduced their appetite for energy. Indeed, the most common exit signs sold today, those using LED lighting, use as little as two watts—one-twentieth the electricity consumed by older incandescent models. And some exit signs today don’t use any electricity at all.

This article examines the full range of exit signs available and provides recommendations of what makes the most sense and why. We’ll address why the new and widely touted photoluminescent exit signs do not make sense in many common applications.

Published October 27, 2006