Tuesday, March 10, 2009

Day for Night

Maybe it's me, but I get jet-lagged when we change the clocks in the spring and fall. And this year we changed them earlier than I was expecting. But was it a good idea? The most recent issue of Scientific American (and other studies and articles I have seen) suggest that DST may not have quite the benefit we think it does:
People may think that with the time shift, they are conserving electricity otherwise spent on lighting. But recent studies have cast doubt on the energy argument—some research has even found that it ultimately leads to greater power use.

Benjamin Franklin is credited with conceiving the idea of daylight saving in 1784 to conserve candles, but the U.S. did not institute it until World War I as a way to preserve resources for the war effort. The first comprehensive study of its effectiveness occurred during the oil crisis of the 1970s, when the U.S. Department of Transportation found that daylight saving trimmed national electricity usage by roughly 1 percent compared with standard time.

Scant research had been done since, during which time U.S. electricity usage patterns have changed as air conditioning and household electronics have become more pervasive, observes economist Matthew Kotchen of the University of California, Santa Barbara. But lately, changes to daylight saving policies on state and federal levels have presented investigators new chances to explore the before-and-after impacts of the clock shift.

In 2006 Indiana instituted daylight saving statewide for the first time. (Before then, daylight time confusingly was in effect in just a handful of Indiana’s counties.) Examining electricity usage and billing since the statewide change, Kotchen and his colleague Laura Grant unexpectedly found that daylight time led to a 1 percent overall rise in residential electricity use, costing the state an extra $9 million. Although daylight time reduces demand for household lighting, the researchers suggest that it increased demand for cooling on summer evenings and heating in early spring and late fall mornings....

Investigators got another opportunity in 2007, when daylight time nationwide began three weeks earlier, on the second Sunday in March, and ended one week later in the fall. California Energy Commission resource economist Adrienne Kandel and her colleagues discovered that extending daylight time had little to no effect on energy use in the state. The observed drop in energy use of 0.2 percent fell within the statistical margin of error of 1.5 percent.
Interestingly, I am apparently not alone in experiencing adverse effects of DST (even if mine are purely imaginary):
Researchers at the Karolinska Institute in Stockholm and their colleagues looked at myocardial infarction rates in Sweden since 1987 and found that the number of heart attacks rose about 5 percent during the first week of daylight saving time (called summer time in Europe). In the October 30, 2008, New England Journal of Medicine, they suggest that this rise may result from the disruption of sleep patterns and biological rhythms.
But then:
the clock shift could help prevent traffic accidents by enabling more people to drive home in sunlight.
Yeah, but those people are usually driving while on cellphones, making them more susceptible to crashes, while at the same time causing heart attacks in those of us who are not on cellphones and have to deal with them. So it's pretty much Carnage-A-Go-Go either way.

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