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I have two questions. Recently, in the quest for energy efficiency, I converted my compact florescent light bulbs to lumen comparable, very expensive standard AC Edison based LED bulbs with the AC/DC rectifier and heat sinks built into the base. Cognizant that most of the energy consumed by a light bulb is dissipated as heat, I was surprised and dismayed when touching LED bulb's heat sink to find much more heat than I expected. The heat was about the same as a lumen comparable CL (compact florescent). My subsequent research confirmed that the two AC bulb technologies have relatively the same efficiency, LEDs being only bit more (less than 10%) efficient than its less expensive mercury-laden competitor (CLs). I have the LED bulbs on dimmers (another small advantage over most CLs for aesthetics.) When touching the LED's heat sinks in this dimmed state, they seem as warm or maybe even warmer compared to the LED's max lumen dimmer setting. During the heating season, heat generated from lighting is a welcome addition to our household environment but always more costly when compared to the firebox. Conversely, fixture heat generation during air-condition season is unneeded and unwanted. Firstly, given the energy loss in the dimmer (they get warm too), is my current LED setup in a dimmed aesthetically pleasing state possibly less efficient than the previous CF configuration?
Secondly, I also have a dimmable parallel LED recessed puck cabinet lighting system utilizing a single AC/DC 12 volt transformer (that gets warm). When comparing for efficiency this standard 12v system to the standard, rectifier and heat sinks on each, AC Edison based LEDs, which configuration of the two offers the least energy usage per lumen?
- al (age 45)
Narragaensett, RI USA
You're right that dimmers themselves aren't completely efficient, so that getting the same light from a smaller number of either CFLs or undimmed LEDs would use a bit less power, at the cost of not getting the type of lighting you want. However, by far the biggest power saving comes from what you've already done- switching to these bulbs over incandescents. Probably there are now other areas (home insulation, type of heating/ac system, transportation) where you could get far bigger energy savings than by trying to fine-tune your lighting. (I switched to CFL's a long time ago, but am just getting around to improving home insulation, which will give comparable savings.)
I don't know the answer to your second question, although I'd guess again that the differences are fairly small compared to the savings you've already made and those that could be achieved in other energy uses.
(published on 01/29/12)
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