Matthew Fitzsimmons

A Tale of Two Bulbs

CFL and LED light bulbs

I got an infrared thermometer yesterday, and was playing around with it. I decided to take a look at some of the heat sources in the house.

It's a little hard getting the temperature of a light bulb because you can't really see the aiming laser on the light once you point it at a light source, but with a little work you can make it happen.

To start with, these are both 60W equivalent bulbs, so I'm comparing bulbs with similar purposes as near as I can. I'm not sure what the lumen ratings on each bulb is, but they seem functionally similar as near as I can tell with the naked eye.

It turns out that my CFLs run significantly hotter than the LEDs. When I measured the two bulbs in the picture above, the CFL topped out at about 157°F and the LED was about 98°F. That's a rather significant difference. In addition to this, the LED uses less energy (8.5W vs the CFL's 14W).

In my experience, the CFLs are also less reliable. The reason that LED bulb is there in the first place is that the CFL that was supposed to be there died the first time I turned it on. I have a number of LEDs, a couple of which have been running almost full time for several years. When I put CFLs in the can lights in the kitchen (yes, I used CFLs that were designed for can fixtures), they started dying after only a few months. Some lasted longer, but I ended up having to replace some of them with the incandescents that had been in there before (which had lasted 6 or 7 years without any of them dying). After awhile, I got frustrated and switched them all to LEDs. I haven't had a single problem yet in the couple of years I've been using the LEDs.

The only disadvantage is that the LEDs are still more expensive than CFLs. I hope this eventually changes as they become more popular, but I don't doubt that I'll get close to the advertised lifespan of my LEDs, when my CFLs can't even reliably outlive incandescent bulbs.


  • LED bulbs use less energy than CFLs
  • LED bulbs generate significantly less heat than CFLs
  • LED bulbs are more reliable than CFLs
  • CFLs are cheaper than LED bulbs

I've known about all of these advantages before except the heat issue. Knowing that the CFLs run at 50% higher temperatures when I'm trying to keep my house cool in the summer is just another link in the chain that makes me recommend them without hesitation. The cost issue is not a huge disadvantage to me in relation to the expected lifespan and CFL reliability issues.