A QUICK (random, nonrigorous) CFL - LED COMPARISON

D. W. Koon



At lunchtime today, I hopped on over to [Hardware Store #1], then to [Hardware Store #2] to pick up some LED lamps. I bought two $10, twist-in 40W replacements from the first store. They seemed to have only a handful more left (but that will change if a bunch of us come in asking for them). Store #2 had a larger assortment, including these 40W replacements, so I bought two $20 45W replacement bulbs from them. I came back to the lab and measured their spectra, which I present below, compared to the spectra of a 20W CFL and the overhead lights in my laboratory, and an incandescent bulb.
Here's a handy summary of the bulbs tested:





LED screw-in

40W incand.



LED flood

45W incand.



CFL screw-in

75W incand.


(on sale)



1.5W “Decor LED Accent” from Lights of America

3.5W “LED Flood” from Lights of America

20W CFL from Sunpark.


The LED screw-in was pretty dim. I do not recommend it. The floodlight appeared noticeably brighter. I haven't tried to subjectively compare the LED floodlight and the CFL, but the CFL is certainly not cranking out 6x the light of the LED, even though that's how much more electricity it consumes.

The incandescent grew very hot very quickly; the CFL was warm after less than a minute's work. The LED lamps did not warm up noticeably.

The spectra below are crudely normalized, and the spectrometer cuts off the left and righthand shoulders to a considerable degree. Still, I think we can still make a pretty good comparison.

(Sorry I didn't really answer your question, Bernie)


Thanks to all my colleagues for their comments yesterday and today. I appreciate the added motivation to get out their and learn something new. I look forward to using this in my "Energy" class this Fall.