
This could be a fact or a fable; depending on which study you read.
One of the original goals of Daylight Saving Time (DST) was to save
energy by reducing the need for lighting in the evening. Early research
indicated that DST provided energy savings, but the results of more
recent studies have been mixed; some even concluding that DST increases
overall energy use.
A Brief History
The concept of DST was adopted by the railroad industry during the 19
th century
as a means for standardizing their schedules. During World War I, it
was introduced nationwide as an energy-saving measure. It did not become
a standardized practice until the Uniform Time Act of 1966.
Energy Use and Daylight Saving Time
How does changing the clock conserve energy? The theory is that moving
the clock forward to extend daylight hours enables people to spend more
time outdoors during spring and summer. With fewer hours indoors, less
energy is used for lighting, watching television, or operating
appliances. In the fall and winter, DST adjusts the clock back one hour,
reducing the time between sunset and bedtime.
Does It Save Energy?
Early research that focused primarily on lighting, found that DST did
save energy. Recent studies, which incorporate more comprehensive
energy-use patterns, however, have produced mixed results:
-
In 1975, a U.S. Department of Transportation report found that DST
might reduce the country's energy consumption by 1% in the spring.
-
A 1983 study of European homes found that DST reduced lighting energy
use by 4%, while increasing heating energy use 1.2%. Overall, the study
concluded that DST reduced energy use by 1.8%. (Aries 2008)
-
In 1999, a study of 15 European countries indicated that DST
decreased lighting energy use by 1%, but increased demand for heating by
9%. (Aries 2008)
-
A recent report by the National Bureau of Economic Research found
that DST increases overall residential energy use by 1%. While DST
reduced overall electrical consumption for lighting, these savings were
offset by increases in heating and cooling demand. (Kotchen 2010)
Others believe that the energy savings depends on where you live.
Those living in northern states may save slightly because there is less
demand for air conditioning. However, those living in southern states
may use more energy during DST because the demand for air conditioning
is greater. Still, there may be other benefits to daylight saving: an
increase in tourism since people tend to be more active outdoors; a
reduction in crime rates because crime tends to happen in darkness; and a
decrease in traffic accidents because fewer people are driving home
from work after dark.
Energy Policy Act of 2005
The Energy Policy Act of 2005 extended DST three weeks in the spring
and one week in the fall, beginning in March of 2007. What effect has
this had on energy use? Once again, the reports are mixed. A 2007 study
by the California Energy Commission concluded that the extension of DST
had "little or no effect on energy consumption." (CEC 2007) A U.S.
Department of Energy report, however, concluded that total energy use
decreased 0.5% per day of extended DST; roughly 0.03% of total annual
energy use. Energy savings occurred in the evening, with a slight
increase in energy use during morning hours. Energy savings were
slightly greater during the spring than in the autumn. (DOE 2008)
The Future of Daylight Saving Time
Evidence that DST saves energy is mixed and contradictory. This may be
due to inconsistencies in study methods, as well as technology and
lifestyle changes since its inception. Lighting systems are much more
efficient, and energy-use patterns for heating and cooling systems have
changed significantly. It is likely the increased use of computers and
electronics have reduced the impact of DST on overall energy use as
well.
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 the
cost and benefits of DST and comparing it with other energy conservation
methods. When it comes to public opinion, a 2010 national telephone
survey by Rasmussen Reports found that many people "don't think the time
change is worth the hassle."
References
Aries, M.B.C.; Newsham, G.R. "The Affect of Daylight Saving Time on Lighting Energy Use: A Literature Review."
Energy Policy, v. 36, no. 6, June 2008, pp. 1858-1866.
California Energy Commission (CEC).
The Effect of Early Daylight Savings on California Electricity Consumption: A Statistical Analysis. May 2007.
Gurevitz, Mark.
Daylight Saving Time. Congressional Research Service Report RS22284. March 7, 2007.
Handwerk, Brian. "
Daylight Saving Time 2012: Why and When Does It Begin?"
National Geographic Daily News, March 9, 2012. (Last accessed October 11, 2012).
Kotchen, Matthew and Grant, Laura. "
Does Daylight Saving Time Save Energy? Evidence From a Natural Experiment in Indiana." To be published in
The Review of Economics and Statistics. February 10, 2010. (Last accessed October 11, 2012).
U.S. Department of Energy (DOE).
Impact of Extended Daylight Saving Time on National Energy Consumption. Report to Congress. October 2008. (Last accessed October 11, 2012)