This is an excerpt from EERE Network News, a weekly electronic newsletter.

March 07, 2007

Energy Policy Act Starts Daylight Saving Time on March 11th

One of the more obscure features of the Energy Policy Act of 2005 is its addition of four additional weeks of Daylight Saving Time (DST), a change that causes DST to start on Sunday, March 11th, this year. DST normally would have started on the first Sunday in April, but now starts on the second Sunday in March. DST will also last longer, ending on the first Sunday in November (November 4th this year) instead of the last Sunday in October. The change is meant to save energy by providing more daylight during the evening, although the savings may be offset by increased energy use in the morning. DOE is tasked with studying the energy savings of the change and reporting back to Congress by December, and Congress has reserved the right to switch back to the old system. See a brief summary of the DST change on the WebExhibits Web site, and for the actual legislation, see pages 52 and 53 of the Energy Policy Act of 2005 (PDF 2.6 KB). Download Adobe Reader.

This isn't the first time that DST has been tampered with. According to a press release and article on the California Energy Commission (CEC) Web site, DST was first instituted nationwide as an energy saving measure during the first and second world wars, but states and localities had long had the freedom to institute DST on whatever schedule they chose. In 1966, Congress instituted the Uniform Time Act to set the dates for shifting to DST, but allowed areas to exempt themselves from DST by enacting a local ordinance. DST was extended in 1974 and 1975 in response to oil embargoes, but the change was reversed in 1976. And in 1986, the DST start date was changed from the last Sunday in April to the first Sunday in April. The CEC has also prepared a technical paper that concludes the DST change may not save electricity in that state, but should reduce the peak load in the evening. See the CEC press release, article, and technical paper (PDF 574 KB). Download Adobe Reader.

The main concern with the change in DST is its likelihood of creating problems for devices that automatically change time on the old schedule, including computers. If your electronic appointments for late March are an hour off, you have a problem. Apple says that the latest version of its Mac OS X operating system accounts for the change, and updates are available for other recent operating systems. Microsoft has an extensive Web page dedicated to the problem, as well as a special support page. Sun Microsystems notes that Java programs can display times wrong if they're using an older Java Runtime Environment. See the Apple Web site, the Microsoft Web site and support page, and the Sun Web site.