Improvements in CFL Technology

Analysis by on October 15, 2007 at 6:33 pm

I didn’t ‘sign up’ for Blog Action Day, but I’m passionate about the cause and thought I’d contribute a relevant post.

I’ve been excited about Compact Fluorescent Lights (CFLs) for a while for a few reasons:

  1. CFLs save people money. Switching to CFLs is a fundamentally good economic decision
  2. Anyone can make the switch and begin using the bulbs
  3. CFLs drastically reduce energy consumption

The Energy Star program has collected a ton of interesting data over the years about CFL bulbs that they’ve certified.

I think we’re all aware about the reduction in costs for CFL bulbs over the years, but I was interested in how the technology has been improving over the years. Is it actually getting better?

I used the raw Energy star data to look at two metrics of CFL technology:

Bulb Life


I took the Energy Star data and calculated the average bulb life for the bulbs approved by the Energy Star program for every year available. This does not represent a true weighted average of bulbs sold, but I think it probably provides a good representation of the direction of the technology.

All told, bulb life has increased by 38% since 1999. That’s a pretty solid improvement, especially since its been happening while prices have been plummeting.

Lumens per Watt

Lumens per Watt of CFL Bulbs

Lumens per Watt isn’t a published metric, but it is easily derived and seemed to me to be the best indicator of the true energy savings that CFL bulbs can provide. For perspective, a standard incandescent bulb provides a mere 16 Lumens per Watt.

Please note the truncated y-axis in this graph. The actual improvement from 99 to 07 is only about 9%. I hate when people do this, but the trend isn’t clear with a properly proportioned axis (where the y-intercept is at 0).

Anecdotally, I’ve seen that CFL bulbs emit a more natural light now than they did several years ago. Even though Energy Star tracks the correlated color temperature metrics for the bulbs, they don’t make that data easily downloadable.

Drawbacks of CFL technology

The primary drawback of CFLs are the limited amounts of mercury in the bulbs. Most scientists believe that they don’t pose much of a threat to people, but they do require special disposal.

What now?

Go buy some bulbs ( It doesn’t even make economic sense to wait for your existing bulbs to burn out - replace them now! If you’re unsure which bulbs to buy, check out this great CFL bulb test conducted by Popular Mechanics.


  1. sa — October 16, 2007 @ 8:18 am

    your amazon link is broken. i think.

  2. Dave Naffziger — October 16, 2007 @ 10:02 am

    That’s lame. I think I fixed it, but the URL looks awfully similar to the first one I copied and pasted in.

  3. mathew johnson — October 17, 2007 @ 8:42 am

    killer new theme, bro!

  4. Kiran kumar — July 16, 2011 @ 11:40 am

    Dear Friends, 

    My friend has developed a CFL circuit which will work even after the filament is cut. This circuit will perform all safety standard tests.

    This circuit require only 2 wires to glow the bulb as normal circuit require 4 wires. 

    This circuit is not burning the filament for glowing.  

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