Design Green Design Can the ESL Knock Out the CFL? Perhaps, but Not the LED. By Lloyd Alter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. our editorial process Facebook Facebook Twitter Twitter Lloyd Alter Updated October 11, 2018 Migrated Image Share Twitter Pinterest Email Design Tiny Homes Architecture Interior Design Green Design Urban Design VU1 Compact Fluorescents are not without their problems; a lot of people don't like the light from them and disposal is an issue. But LEDs are still expensive. Enter the ESL bulb, short for Electron Stimulated Luminescence. Core77 writes that they have just received UL approval, a necessary step for coming to market, and the Seattle based company VU1 says they will be on the market in early 2011. The company claims that the bulbs have much better light quality, comparable to full-spectrum incandescent light. Electron Stimulated LuminescenceTM (ESL) Lighting Technology is an entirely new, energy efficient lighting technology. It uses accelerated electrons to stimulate phosphor to create light, making the surface of the bulb "glow". ESL technology creates the same light quality as an incandescent but is up to 70% more energy efficient, lasting up to 5 times longer than incandescent and contributing to the reduction of greenhouse gas emissions. There is no use of the neurotoxin Mercury (Hg) in the lighting process. The bulb works like an old cathode ray tube, with an electron gun of some sort firing a spray of electrons at a screen with a proprietary phosphor. It fits in standard Edison sockets. It is not without its limitations. It pumps out 30.7 lumens per watt, giving a 19.5 watt bulb the lighting equivalent of a 65 watt incandescent bulb. That is half the efficiency of modern compact fluorescents or LED fixtures. (Mike has shown us some LEDs that get 140 lumens per watt) It lasts 10,000 hours, three times what an incandescent might, but that is a quarter of the life of an LED. It can operate in any position without overheating, which is a problem with CFLs. It is instant on at full brightness. It has a colour rendering index (CRI) of 85, which is excellent. On the other hand it is only twenty bucks, a lot less than the equivalent LED. Smells like an interim technology, but I would only swap out the CFLs where the colour temperature was a really important issue, they are still far more efficient. And in the long run, the efficiency of LEDs will put these to shame.