Outdoors operation will do that. Also if its a portable that gets knocked around, impacts will cause phosphor to fall off the inside surface of the bulbs and cause dimming.KitemanSA wrote:My big problem with CFL is that even though they are supposed to last a long time, and the way I use them they do, they lose brightness with time. My "100W" equivalent bulb dims to 60 or even 40 in a few standard incandecent lives. So even though it still "works", it doesn't really function as it should. Makes the economic equation difficult to resolve.
in lumens per watt, LED's are actually significantly more efficient than CFL. Back in the early 1990's I was in the exist sign retrofit market with my electroluminescent retrofit, competing against CFL, LED and tritium signs and retrofits. LED was slightly less efficient than EL, but still in the 90%+ savings vs the original incandescent. CFL would range from 50%-70% savings in electrical efficiency.
The bigger savings, as Tom says, is in the labor savings. LEDs and EL tech last 20-30 years in indoor applications, 5+ in outdoor apps. Not having to change bulbs as frequently counts for a lot, typically 3-10 times more savings on the labor side than the energy side.