Does Daylight Savings Time save energy?

The practice of setting clocks ahead in the spring and back in the fall was first implemented by Germany and Austria-Hungary in 1916 and now impacts one-fourth of the world’s population. The idea is to reduce residential energy use, which is heaviest in the evening – an extra hour of daylight when a worker returns home at night means electrical lights are turned on an hour later than usual.

Daylight Savings Time (DST) has become so ingrained in the public consciousness that few question it or its purpose (many believe it has something to do with farming – actually there is no connection at all and farmers have traditionally opposed DST because it disrupts their schedules).

Numerous studies have dispelled the idea that DST reduces energy use. Perhaps the most compelling was a National Bureau of Economic Research paper from 2008 that examined electricity use in the state of Indiana. Until 2006, DST participation in Indiana was not statewide but on a county-by-county basis. This provided a perfect opportunity for comparing DST- and non-DST-participating counties in a similar geographical area, over the same time period (in this case, from 1976 – 2006). The statistically-significant conclusion was that DST resulted in a one percent overall INCREASE in residential electricity demand. Other studies suggest a possible reason for this: sleeping habits change somewhat during DST – people tend to sleep 15 – 20 minutes less and spend that extra time at home. This results in increased lighting and heating use during that relatively colder and darker period.

The Indiana research has been corroborated by a number of other papers. A notable 2007 study of two neighboring Australian states (one in which DST had been extended for the 2000 Olympic Games) found that decreased energy use in the evenings was virtually negated by increased use in the mornings.

DST dates in the United States were previously the first Sunday in April and the last Sunday in October. In 2007, Congress changed the “spring forward” date to the second Sunday of March and the “fall back” date to the first Sunday in November. The main lobbyist for the latter change? Halloween candy manufacturers, who wanted an extra hour of daylight for trick-or-treaters.