Indiana's change of heart gave University of California-Santa Barbara economics professor Matthew Kotchen and Ph.D. student Laura Grant a unique way to see how the time shift affects energy use. Using more than seven million monthly meter readings from Duke Energy Corp., covering nearly all the households in southern Indiana for three years, they were able to compare energy consumption before and after counties began observing daylight-saving time. Readings from counties that had already adopted daylight-saving time provided a control group that helped them to adjust for changes in weather from one year to the next.
Their finding: Having the entire state switch to daylight-saving time each year, rather than stay on standard time, costs Indiana households an additional $8.6 million in electricity bills. They conclude that the reduced cost of lighting in afternoons during daylight-saving time is more than offset by the higher air-conditioning costs on hot afternoons and increased heating costs on cool mornings.
"I've never had a paper with such a clear and unambiguous finding as this," says Mr. Kotchen, who presented the paper at a National Bureau of Economic Research conference this month.
The energy-savings numbers often cited by lawmakers and others come from research conducted in the 1970s. Yet a key difference between now and the '70s -- or, for that matter, Ben Franklin's time -- is the prevalence of air conditioning.
"In an inland state like Indiana, it gets hot in the summer," says Steve Gustafsen, a lawyer in New Albany, Ind., who filed a suit in 2000 in an effort to get his county to abandon daylight-saving time. "Daylight saving means running the air conditioner more."
Sunday, March 02, 2008
Another reason to hate DST
Daylight Saving Wastes Energy, Study Says: