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# Percent of Increase

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Time Savers
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Credit: Ross Berteig
Source: http://www.flickr.com/photos/rberteig/177100826/

Throughout the world, most countries practice daylight saving time (DST). DST is supposed to save energy in the spring and summer by coordinating schedules to the sun. When it stays dark later at night, people don’t need electricity to light their houses. In recent years, the United States extended DST into November. But does “daylight savings” really save anything?

#### The Indiana Experiment

When the rest of the U.S. went on daylight saving time, Indiana did not. Most of the counties in the state stayed on the same time year round. That changed in 2007. Economists studied the state to see if the change to DST caused Indiana residents to use less electricity. They found that DST actually resulted in a 1% increase in Indiana’s electricity usage. People used more natural light, but they also used more air conditioning.

DST ended up costing the state an additional $9 million a year. Even worse, Indiana obtains most of its electricity from coal-powered plants. That means that DST also produces an extra$5 million a year in damage from pollution. The researchers predicted that DST uses even more energy in states with higher temperatures and more air conditioning units.

Source: http://www.flickr.com/photos/derfokel/2624564527/

The scientists also discovered other costs to DST. When it’s light longer, people want to go out and have fun. They go to concerts, sporting events, and parks. But they drive to all these places, so they use extra gas. DST also seems to cause an increase in car accidents and heart attacks. This might be because changing schedules by an hour leaves people exhausted and unable to function.

#### Explore More

When Indiana adopted daylight saving time, a 1% increase in electricity usage cost state residents an additional \$9 million a year. How much were they spending before DST?