Bless it or curse it, Daylight Saving Time strikes again on Sunday, and citizens of 48 states must turn their clocks forward and sacrifice one hour of sleep to save energy through the summer.
But in a modern society that pays very little attention to the sun when scheduling its days, does one hour's twice-annual shift really make a difference?
When Benjamin Franklin first developed the idea in line with his "early to bed, early to rise" maxim, he thought it might save candles. German Emperor Kaiser Wilhelm II first instituted the clock-changing practice during World War I to conserve electric power, and the United States followed suit, both then and again during World War II, The Christian Science Monitor's David Scott wrote. With the exception of Arizona and Hawaii (where the thinking goes that saving daylight is hardly necessary), Americans alter their clocks to conserve energy.
Congress, which has tried unsuccessfully to alter the 1966 law that standardized Daylight Saving Time on several occasions, has initiated two federal studies on the system's efficacy, according to a 2016 report by the Congressional Research Service. A 2006 study found electricity savings from the time system to be "relatively small," recording savings of 1 TeraWatt-hour, or an estimated "7 to 26 Trillion Btu (TBtu), or 0.01 percent to 0.03 percent of total annual US energy consumption."
A 2008 study offered roughly the same data, suggesting energy savings nationally of 1.3 TeraWatt-hour, or 0.03 percent saved each year. By contrast, the nation's Christmas light displays require a total of 6.3 billion kilowatt hours, or 6.3 TeraWatt-hours of energy, each year, Phys.org reported last December. Hypothetically, the nation could save roughly six times more energy annually by ditching Daylight Saving Time and asking holiday-makers to trade out their Christmas lights for popcorn strings.
Even worse, a 2010 study in Indiana that used the state's split among time zones to create a natural control group suggested Daylight Saving Time requires people to use more energy overall than they would if they simply left their clocks alone. Energy users in Indiana turned their lights off sooner because of the time shift, but they made up for it by using more energy in heating and cooling, researchers from Yale University and the University of California-Santa Barbara wrote in the Review of Economics and Statistics. They suggested Daylight Saving Time costs Indiana households $9 million per year, with a slightly more ambiguous "social cost" of $1.7 to $5.5 million annually because of pollution.
A widely cited review of such studies from the journal Energy Studies in 2007 was ambivalent:
Simple estimates suggest a reduction in national electricity use of around 0.5 percent, as a result of residential lighting reduction.... However, there are just as many studies that suggest no effect, and some studies suggest overall energy penalties, particularly if gasoline consumption is accounted for. There is general consensus that DST does contribute to an evening reduction in peak demand for electricity, though this may be offset by an increase in the morning.