... But the great news is that CFLs are/were just a stepping stone on the way to LED lights which provide the energy savings and no mercury. ...
Agreed, and I just did a little research that indicates that LED efficiency improvements are still ongoing. The LED 'bulb' I just bought to try out is ~ 63 lumens per watt (850L/13.5W), and CREE has lab samples of LEDs at 300L/W - lab is different from 'on the shelf', but at least there is some room to grow, and predictions indicate we will see ~ 2X improvement in the next 10 years. Now that has diminishing returns on energy savings, but it directly relates to heat generation in the 'bulb', and if heat is cut in half, cost comes down (half as many LEDs for the same light), weight and size come down, reliability goes up.
So yes, I think CFLs will fall out of favor in a few years. I wish they'd drop the stupid filament ban, as I'd rather put a super-cheap, reliable filament bulb in my low use sockets than a CFL, and LEDs are still too expensive for those sockets. The 'loop-hole' is to use 'rough service' bulbs in those sockets, those are not banned - and they are
less efficient than standard filament bulbs.
We have a half bath adjacent to the kitchen. This bathroom has a 6 bulb light fixture above the mirror. Family members are not well trained to turn off the lights when they leave a room.
When I had incandescent bulbs in the bathroom the room would get unreasonably warm and the bulbs would last only about a year or less. I replaced them with CFLs and that help the heat issue.
Next I replaced the light switch with a motion sensor switch with a variable time delay to turn them off. This caused a flickering of the CFLs when no one was in the bathroom and the garage door was open allowing daylight to reflect into the room. This flickering, I think caused a high failure rate of the CFLs.
When LED bulbs of the needed luminosity became available and affordable, I replaced the CFLs with 60w equivalent Cree bulbs.
The flickering stopped but two of the 6 LED bulbs failed within 6 months. ....
Here's a work-around for those types of motion detectors or timers - if you replace 1 or 2 of the CFLs or LEDs with a low wattage filament bulb, that will very likely make the motion detector/timer work properly and eliminate the flickering. Basically, those devices need a small constant load on them when they are 'off' - CFLs and LEDs don't provide the same kind of simple resistive load as a filament does.
That flickering is bad for the device, and bad for the CFL/LEDs. But 1 or 2 small filaments should be enough to provide an 'off' current, and damp out the reactive loads from the CFL/LEDs.
Two thoughts on CFL and LED bulbs and their life expectancy.
According to articles I have read, some of the cheap ones will fail early not because the the light emitting part of the bulb fails but because the electronics that control the bulb fail. I have had CFL's that have lasted barely 2x the life of an incandescent bulb and others that have worked for many times that. ...
Yes, there are electrolytic capacitors that degrade with heat. They may have a life expectancy of only 2000 hours in some designs. Higher life caps cost more, and there is a cost war going on, so it's hard to make an informed purchase, but don't expect anywhere near those 25,000 hour ratings...
Second thought: I understand (please correct me if this is wrong) that the published lifespan of the bulb is an statistical midpoint. They line up 100 bulbs, turn them on and when the 50th bulb burns out, that midpoint becomes the expected lifespan of the bulb. So, if you are unlucky enough to buy a bulb that is in the first few percent to fail you will wonder why you bothered. OTOH, if you buy a bulb that is in the last few percent to fail, you will congratulate yourself on a very wise purchase.
It's even worse than that, far worse. Yes, it is based on a median figure, but that figure is NOT based on how long the bulb lasts. It is a measure, based on extrapolation of much shorter test times, as to when half the 'bulbs' will reach 70% brightness. But the test is done over a shorter time, so they may not be hitting the failure modes of the other components.
Those capacitors are fairly well characterized, they have a good idea of how long they will last at elevated temperatures, so they can make reasonable predictions of bulb life based on the components and the temperature they see in an LED bulb. But they are not doing that, they are using this stupid 70% dimming value.
-ERD50
