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.
Personal Energy Meter
More About Energy
The Great Energy Challenge is a National Geographic initiative to help you understand our current energy situation. Explore the GEC to figure out and trim your carbon footprint.
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See which countries pay the most for tax breaks and other mechanisms that keep fossil-fuel prices down.
How much could you save yourself, and the world, by switching to more efficient bulbs? Use this tool to find out.
An interactive view of how regions and countries around the world generate their power.
Learn more about the energy-saving projects being funded as part of National Geographic's Great Energy Challenge program.
The Big Energy Question
How do we make cities sustainable?
@NatGeoGreen on TwitterTweets by @NatGeoGreen
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The Arctic: The Science of Change
See video on Vimeo: Experts at our live event in London share their perspectives.
As shipping and energy activity increase in the region, what do we urgently need to learn more about? Vote and comment on the list.
Special Report: Shale Gas Rush
The shale gas industry maintains that it protects drinking water and land. But mistrust has been sown in rural communities.
The industry promises jobs to a state badly in need of an economic boost, but the work so far isn't where you might expect it to be.
Track the growing mark that energy companies have etched on Pennsylvania since first producing natural gas from shale.