Exit signs save lives. Certain exit signs can also save energy.
Some exit signs are electric powered and others use no electricity at all. Clearly, the most energy-efficient choice is one that uses no electricity.
Instructions
1. Consider the radioluminescent (RL) type of sign. RL signs provide illumination through low-level nuclear decay. While RL signs use no electricity and last up to 20 years, if broken they pose health and environmental risks due to radiation. Furthermore, their disposal is costly and highly regulated.
2. Consider the photoluminescent (PL) type of sign. PL signs use a "glow-in-the-dark" substance -- a photoluminescent material that absorbs and stores enough light from ambient light sources to illuminate in the dark. PL signs use no electricity but require an ambient light source for approximately an hour, which varies depending upon the manufacturer.
3. Of the PL types, consider one of the new, brighter types. Some PL exit signs as of October 2010 used pigments based on strontium oxide aluminate (SOA) chemistry. These pigments are up to ten times brighter than conventional zinc sulfide or radioisotopic pigments used in RL signs.
4. Consider whether ambient light at your exit sign locations is sufficient for PL signs. Each manufacturer has its own specifications; two on the market in October 2010 require 5 foot candles of fluorescent, metal halide or mercury vapor light shining on the face of the sign for 60 minutes, to illuminate 33 hours. A foot candle is the illumination produced by a standard candle at a distance of one foot. The average office space provides 50 foot candles.
5. Of the electric-powered choices, consider those that use light emitting diode (LED) arrays. According to the U.S Department of Energy, of the electric choices, LED arrays are the most energy efficient, using approximately one-fifth the annual energy compared to those that use compact fluorescent lamps (CFL). Incandescent bulbs use the most energy and should not be considered.
6. If you are replacing electric with LED electric signs, turn off the power at the circuit panel. Unscrew the old mount from the wall, use the new mount supplied with the new sign and screw it to the wall. Rewire each new sign according to manufacturer directions. If you are replacing electric with non-electric signs, disconnect and cap off the old sign's wires. Measure the distance between the screw mounts on the back of the new signs and attach screws to the wall at that exact distance. Hang your signs.
