From the early, humorous musings of Benjamin Franklin to the first widespread implementation of daylight savings during World War I and into the present day, observing DST has had a foundation in energy savings.
Lighter evenings mean lower demand for illumination and electricity, the theory goes. But studies question whether daylight saving time produces any gains at all—and some suggest it may have the opposite effect.
Indiana, once home to counties that both did and did not observe DST, adopted the practice statewide in 2006.
That unusual event meant Matthew Kotchen, an environmental economist at Yale, and colleagues could compare before-and-after electricity use across the state.
In their 2008 National Bureau of Economic Research study, the team found that lighting demand dropped, but the warmer hour of extra daylight tacked onto each evening led to more air-conditioning use, which canceled out the gains from reduced lighting and then some: Hoosiers paid higher electric bills than before DST, the study showed. (Related: “Extended Daylight Saving Time Not an Energy Saver?”)