Five Percent: Conserve Energy

Climate Change Is Important: Energy Conservation is the First Step

December 16, 2006

New Dimmable CF Flood that Works and has Nicer Light

Category: Conservation,Cool Sites,Household,Save Electricity,Technology,Tips – Tom Harrison – 12:43 pm

Last year around this time I tried a dimmable R-40 floodlight that didn’t really work. On the advice of a commenter on that post, I ordered some Greenlite R40 23W dimmable floods and they are a very good replacement for our incandescent R40 floodlights. They dim smoothly and reliably, and unlike other bulbs we tried, they fit, and the dim down almost all the way — the box says there’s a little integrated circuit in the bulb. The box says the 23 watt bulb uses 70% less energy than a comparable 75 watt incandescent, and that the bulb lasts 6 times longer than a standard bulb. The color of the light is pleasing, even when dimmed, which is one of the major complaints I have with other dimmable CF bulbs.

I got mine from although there are several inaccuracies in their specs: this bulb is a 75W output, not 100W as stated, and in one place they say the color is 2700K (very warm white) and in another 3200K (warm white). On the bright side, I replaced 100W bulbs with 23W bulbs, and while we have less light, we’re using 77% less electricity (actually, I guess that’s both the bright side and the dim side :-)


  1. So do you think the color is closer to 2700 or 3200? Or does the color temperature shift substantially across the dimming range?

    We have a lot of non-dimmable R-40 bulbs in our house. I generally like them, but they take a few minutes to warm up to, and in my experience they haven’t lasted as long as advertised (I’ve replaced 3 already since changing them around a year ago). They definitely cut back the electricity consumption, though.

    Comment by Ho John Lee — December 16, 2006 @ 1:17 pm

  2. Hi Ho John —

    At full power, side by side with a 100W incandescent R40 the color is almost identical, perhaps slightly colder, but not much. At max dimming, the color still shifts towards colder/blue somewhat (the incandescent shifts towards warm/red). Without whipping out my spot-colorimeter, I can’t say but I would guess 2800K at max and in the high 3K’s when dimmed. These are much better than standard spiral dimmable CF bulbs that I have in my office, which were supposed to be 2700K but maybe start at closer to 4000K and get colder as you dim. In other words, I think the new lights are … better.

    We’re still working on replacing the ones in the kitchen which are PAR20 Halogens. I don’t think the dimmable CF technology is quite there yet. Maybe next year :-)

    Comment by Admin — December 16, 2006 @ 2:31 pm

  3. […] went to Home Depot today for dimmable CFLs, a water heater blanket, a low-flow shower head, leaf bags and a few other things. After walking […]

    Pingback by Home Depot is Dim (Why Can’t They Market CFLs Brightly) | Five Percent: Conserve a Little Energy — November 25, 2007 @ 7:08 pm

  4. I looked on the 1000bulbs site and they no longer sell the greenlite version. Has anyone tried others and/or know where else to find the nice greenlite version? I’m getting some recessed lighting install this month and wanted to put dimmable CFLs in them.


    Comment by David — January 9, 2008 @ 3:34 pm

  5. David — I am currently a bit miffed at 1000bulbs — I got a bunch of dimmable PAR 30 bulbs which were supposed to fit in the (dimmable) overhead light sockets in our kitchen, replacing PAR 20 halogen bulbs. The brand they sent, “Neptun” was absolutely terrible. The color was downright magenta, they buzzed, and the were poorly contructed. The Greenlight R40 bulbs I wrote about here were significantly better, although still not great (the color temperature gets colder as they dim).

    Last I checked Greenlight seemed like a pseudo-brand managed by a Canadian company (nothing against Canada, just reporting the facts), but I can’t find them any more. Perhaps only I wasn’t the only dissatisfied Greenlight customer :-)

    If you are replacing R40 bulbs, see if you can find GE Energy Smart dimmable CFLs. My neighbor has them in his kitchen and they are remarkably good — nice color, and dim pretty well (if not perfectly), and are by far the best dimmable CFLs I have seen. I tried finding them on the GE Lighting website, but couldn’t, but I have the box still from my neighbor. He said he got them from our local electric company as part of a promotion, so perhaps they are not commercially available, or something. Anyway, they are the only ones I have seen that are any good, and they were R40 size, not smaller.

    If it makes you feel better, even incandescent bulbs use less electricity when dimmed. My opinion is that dimmable CFLs are not “there” yet. Until then, use the dimmer, and make sure to turn them off as you leave the room.


    Comment by Tom Harrison — January 9, 2008 @ 9:32 pm

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