When economist Matthew Kotchen began to study Daylight Savings Time, he knew the issue was a political morass. Under the mandate of energy conservation, the United States has followed “spring forward, fall back” on and off since World War I. Most recently, the 2005 Energy Policy Act authorized the extension of DST an additional three weeks.
Still, Kotchen noted there was thin evidence to back the hypothesis that Daylight Savings Time cuts down on energy costs.
Kotchen, who teaches at the Bren School of Environmental Science & Management at the University of California, Santa Barbara, decided to conduct the first empirical study of DST and energy use.
His petri dish was the notoriously time-ambiguous state of Indiana, where for decades individual counties were free to choose their time zone (Eastern or Central), and whether they would change their clocks in the spring and fall. In 2005, first-time Gov. Mitch Daniels won his campaign to put the entire state on Daylight Savings Time, which he claimed would conserve energy and help business.
Indiana thus presented ideal conditions for a “natural experiment” of the policy’s before-and-after effects.
Using monthly billing data from Duke Energy, a regional service provider, Kotchen and grad student Laura Grant were able to compare the energy consumption of 223,889 households in southern Indiana from 2004 to 2006. Their analysis, which controlled for weather and other variables, produced a surprising result: Daylight Savings Time correlated with a 1 percent increase in household energy use over the course of the year, with a 2 to 4 percent increase in the fall.
They estimate that the switch to DST costs Indiana families about $9 million a year and pumps an additional 188,000 tons of carbon dioxide into the air.
“Two to four percent — that amount of energy is not just a drop in the bucket,” Kotchen said. He believes that any savings from reductions in electric lighting — the original rationale behind DST — are offset by increases in air conditioning in the warm summer evenings and heating in the cool fall mornings. “When we’re talking about so many people, small changes make a big difference.”
Kotchen hoped that his findings would help Congress evaluate the wisdom of the DST extensions made in 2005. The first draft of the study, released in February (the final version appeared last week on the National Bureau of Economic Research Web site ) saw robust media coverage.
However, Kotchen didn’t know his paper would end up roiling the stew of Indiana electoral politics.
Because Indiana is at the westernmost edge of the Eastern Time Zone, the sun rises later according to the clock than in, say, New York. By pushing sunrise forward another hour, Daylight Savings Time means that schoolchildren often begin classes while it is still dark outside. The implementation of DST has proven an emotional experience for Hoosiers. “Daniels is a conniving sob who forced through an unnatural time change AGAINST THE WILL OF THE PEOPLE,” reads a typical comment on the Web site of The Indianapolis Star. “I wonder how an alien culture just in from another galaxy might view this clock changing ritual,” writes another in the Fort Wayne Observed Web site.
Daniels is up for re-election this year, and Kotchen’s paper was an unwelcome development amid his campaign.
“The governor did not have nice things to say about me. I heard him say on a radio program that my research was a pile of bunk,” Kotchen said. (Daniels’ office did not return calls for comment.) Bill Ruthhart, a political reporter at The Indianapolis Star, believes that some voters will use this election as a referendum on the time change, though a recent poll showed that 48 percent of Indianans now support it.
“We’re finding that as time has gone on, the anger has subsided a bit,” Ruthhart says.
Kotchen is concerned less by the outcome of the governor’s race than by the idea that the U.S. may be pursuing a mistaken policy. DST means that working people get home earlier in the evening, which in the summer, especially in the warmer South, means more air conditioning.
“I happen to like Daylight Savings Time — I like having that leisure time in the evening,” Kotchen says. “But if we want DST, we should be carrying out the debate in the context of these other benefits and asking if we’re willing to incur an additional energy cost for them. I’m not a supporter of implementing policies that have the exact opposite effect of their intent.”
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