The Light Bulb Conspiracy

The incandescent light bulbThe schools down here require each kid to participate in science fair from 3rd grade on.  This is not necessarily a bad thing in our house as I am an engineer and everyone in the house has similar interests.  This year my son decided to do his project on light bulbs.  Specifically he wanted to compare the brightness and power consumption of the different types of light bulbs.  We narrowed our sample set down to 3 different kinds of light bulbs: the Edison style incandescent, the compact fluorescent (CFL), and the LED.  What he found out was surprising.

He settled on 6o watt equivalent bulbs or the equivalent.  He one-by-one put the bulbs into a table lamp connected to a watt meter.  He then used a light meter app on the iPhone to measure the brightness of each after a 5 minute warm-up period.   The first thing he discovered was the CFL people are liars.  They advertised on the packaging that the CFL would put out the same light as a 60 watt incandescent for 15 watts.  Not only was the incandescent noticeably brighter than the CFL, the CFL pulled a full 38 watts!  The incandescent only pulled 58 watts and was considerably brighter.  And the CFL cost more than 8X the incandescent.  The LED only pulled 14 watts and was considerably brighter than the incandescent but it cost 80X more than the incandescent.  In fact, the cost analysis to determine how long it would take to make your money back in saved electricity indicated it would take about 24 years to get your money back based on 2011 electricity rates.  And that assumes you only have to buy 1 bulb in that time.  Stick with Edison!

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5 Responses to The Light Bulb Conspiracy

  1. Pingback: Upgrading The Lights - My Thoughts, Ideas, and RamblingsMy Thoughts, Ideas, and Ramblings

  2. Nice website but sometimes the header displays a 404 error, just thought you would like to know

  3. This really answered my problem, thanks!

  4. Anonymous says:

    A data set of one is not evidence, it’s an anecdote. Also, you contradict yourself re the brightness and power draw of CFL vs. incandescent (did the CFL pull 38 or 58 watts and was it brighter or dimmer than incandescent? You claim both). Finally, using a phone app to measure brightness is rather lazy and can lead to weird results unless you know the properties of the optical system. I’d hazard a guess that the phone camera doesn’t have much in the way of IR filtering (and may well use IR for autofocus) so would automatically give incandescents high readings due to heat.

  5. futurecreep says:

    Thanks for your comments. There was a mistake where I referenced CFL when I should have referenced incandescent. CFL pulled 38 watts. Incandescent pulled 58 watts. The CFL advertised only 15 watts. We also ran the test on a larger sample set than discussed in the article. Probably 5 different CFL and incandescent bulbs each purchased over a 4-6 week period from Home Depot. We only purchased 1 LED because it was pretty expensive.

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