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Need To Know: Daylight Saving Time

CNBC.com
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Time Is Everything: The Law In Brief

When

Clocks move forward one-hour at 2 a.m. on the second Sunday in March, three weeks earlier than in the past. Daylight-saving time will also end a week later than usual on the first Sunday in November.

Why

The extension of daylight-saving time was included in the Energy Policy Act of 2005, which contained other, more far-reaching approaches to boosting energy efficiency.

The law requires the Department of Energy to conduct a study within nine months of the change to evaluate how it affected energy consumption. Depending on the result, daylight-saving time may return to its previous schedule.

Pros & Cons

At the time of the bill's passage, the Bush administration opposed extending daylight-saving time, mainly due to the impact it could have on air travel, specifically international air travel. Some in favor of the change have estimated it could cut overall energy consumption by 1%, but the Department of Energy has not conducted any official studies.

Meanwhile, many in the technology field are concerned the change could affect automated timekeeping programs in computer systems and devices ranging from ATM machines to cell phones. Most companies have already begun to address the change through system updates.

Seeing Daylight: A History  Lesson

-- The idea of saving daylight was first mentioned by Benjamin Frankin in a satirical essayin 1784.

-- Britain was the first country to have standard time throughout a region.

-- DST was first seriously proposed in 1907 by  Brirish homebuilder William Willett.Germany was the first national government to put DST into effect – it was April 30, 1916 during WWI.

-- The U.S. established standard time in time zones with the Standard Time Act of 1918. It was repealed in 1919. National and local variations came and went thereafter.

-- DST, as we know it, is the result of The Uniform Time Act of 1966. DST is not observed in Arizona, Hawaii, American Samoa, Guam, Puerto Rico and the Virgin Islands.The European Union’s version of DST, Summer Time, starts the last Sunday in March at 1 a.m. and ends the last Sunday in October.