Extended Daylight Saving Time Saves Energy, Says DOE
March 11, 2009
People throughout most of the United States set their clocks ahead by one hour on March 8 for the start of Daylight Saving Time, marking the third year in a row that Daylight Saving Time started three to four weeks early. The Energy Policy Act of 2005 shifted the start of Daylight Saving Time to the second Sunday in March, rather than the first Sunday in April, and extended it through the first Sunday in November, rather than the last Sunday in October. The shift started in 2007, and the intent was to save energy by allowing people to take advantage of additional daylight in the evening hours. See the article from this newsletter on the shift.
Although some people argued that the increased use of lighting in the morning could easily cancel out the gains in the evening, the data suggest otherwise. A DOE report released last year found that U.S. electricity use was decreased by 0.5% for each day of the extended Daylight Saving Time, resulting in a savings of 0.03% for the year as a whole. The savings are small in percentage terms, but in absolute terms, they added up to 1.3 billion kilowatt-hours, enough to power about 122,000 average U.S. homes for a year. The DOE report did find small increases in electricity use in the early morning hours, but those increases were more than cancelled out by the energy savings in the evening. The shift was also found to have no effect on traffic volume and gasoline consumption. See the DOE report (PDF 285 KB). Download Adobe Reader.