Does Daylight Saving Time Really Save Energy?

Does Daylight Saving Time Really Save Energy?

Does Daylight Saving Time Really Save Energy?

Daylight Saving Time (DST) is the practice of advancing clocks one hour in spring and moving them back to standard time in the autumn. How is changing the clock supposed to save energy? The idea behind moving the clock forward one hour is to provide us with an extra hour of daylight in the evening, giving us the opportunity to spend more time outdoors. When we spend more time outdoors, we use less energy for lighting, watching television or operating appliances.

A brief history of DST

DST is a change in the standard time of each time zone. Time zones were adopted by the railroad industry during the 19th century as a means for standardizing their schedules. Benjamin Franklin first proposed the idea of seasonal time change in 1784, but it was not until World War I that the modern concept of DST was introduced nationwide as a temporary energy-saving measure. It became standardized practice with the Uniform Time Act of 1966. 

DST and energy savings: what the research says 

Although DST has been in use for decades as a way to conserve energy, its effectiveness has been difficult to prove. Early research focused mostly on lighting and found some energy savings was achieved while later studies incorporating wider energy-use patterns produced mixed results.

A report by the U.S. Department of Transportation found that DST reduced electricity use by 1 percent but had no impact on home heating. A European study on the impact of DST found lighting energy use decreased slightly while heating demand increased 9 percent. A recent report by the National Bureau of Economic Research found that while lighting energy decreased, the savings were offset by increases in heating and cooling demand.

    What about the extension of DST that began in 2007? Has this had any effect on energy use? Once again, the reports are mixed. A California Energy Commission study concluded that extending DST had little or no effect on energy consumption. A U.S. Department of Energy report did find a decrease in energy use per day of extended DST but only by 0.5 percent.  

    The lack of solid evidence supporting DST as an energy-saving measure may be due to inconsistencies in study methods and lifestyle changes since it began. Lighting is much more efficient, and overall energy-use patterns are much more complex. It is likely the growing use of computers and electronics has reduced the energy-saving impact of changing the clocks.

    In recent years, there has been debate over whether to end DST or even extend it year-round. Future research will be helpful in weighing its cost and benefits and comparing it with other energy conservation methods.

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