National Geographic Light Bulb Savings Calculator


Editorial:  Interesting idea. Not sure how helpful it is…

From a pure web development standpoint, this calculator is beautiful, elegant, and simple to use.  It uses slide bars to allow you to estimate the number of different types of bulbs in your home then using this information the calculator gives estimates of how much energy you use.  You can determine how much you’ll save by returning to the slide bars and seeing what your savings would be if you switched to more “energy efficient” bulbs and this information when compared is useful.

Up to this point, it’s very nice.  However… the final results page was, in my opinion, disappointing.  It bases the results on a comparison to the average US household.

Seeing the amount that could be saved if everyone in the US did the same as I am doing are very large numbers.   Wow, if everyone was like me they too could save $108 more a year!  But you see, I only have 12 incandescent bulbs in the house that are used on a daily basis.   For instance, even though the dining room chandelier has 6 bulbs, we have 5 of them “unscrewed” so they don’t light for everyday use.

Even though we use only incandescent bulbs, we are saving $108 over the average home.   If I change the calculator to 12 CFLs it says I would save $150 over the average home.

Now look at those two numbers…  If I switched to CFLs I’d save $42 a year in energy costs.  Hummm…  And how much would 12 CFLs cost me to buy?

As you may or may not know, every time a CFL is turned on its life-span is reduced by about 10 hours.  When you use CFLs like a regular incandescent, they can only last 3 – 5 months.

Now, let me get out my own calculator and see just how much money I’ll LOSE by switching to CFLs.

For me personally, LEDs are out of the question as (1) many use fluorescent “base” which my eyes are too sensitive to deal with, and (2) others use blue LEDs which are known to cause permanent and cumulative retina damage.  So, is that risk worth saving $154 over the average US household, or $46 a year over what I’m paying now? … that was a rhetorical question.

~ Trishah Woolley

Calculator Methodology and Credits

This simple calculator assumes that incandescent bulbs are the most common 60-watt bulbs, and that CFLs provide 75 percent savings and LEDs provide 80 percent savings, based on the performance of the models on the market in 2011. Relying on the latest U.S. government and state of California studies, it assumes the typical household lamp is used 1.9 hours per day. The calculator uses the U.S. government’s estimate that the average household has 40 light bulbs. Based on the U.S. market profile for 2010, the calculator assumes 16 percent of light bulbs, or an average 6.4 per household, are CFLs.  Calculations are based on 2010 U.S. Census data showing 113.7 million households in the United States.

Figures on carbon emissions are based on the U.S. Environmental Protection Agency’s assumption of 1.37 pounds of carbon dioxide equivalent (CO2e) for every household kilowatt-hour of energy consumed. The calculator also uses EPA’s green power equivalency assumptions, of 5.1 metric tons of CO2e for every car, 183.65 metric tons CO2e for every coal railcar, and 4,023,304 metric tons CO2e annually for every power plant.

Cost calculations are based on the average residential price of electricity in the United States in 2011, 11.6 cents per kilowatt-hour.

Credits: Programming by Stefan Estrada. Illustrations by H2H Graphics & Design. Text by Marianne Lavelle. Production by Christina Nunez.