Why Your Clock Changes Sunday

November 1, 2007, 8:01 pm
Why Your Clock Changes Sunday
Wall Street Journal

In my print column this week, I write about the numbers used to extend daylight-saving time until Sunday. You'll be turning your clock back this weekend, rather than last weekend, because of numbers from the 1970s, the last time daylight time was extended. These figures suggested that a later sunset can help conserve energy, by reducing the use of lights and other appliances in the evening. But these numbers form a flimsy basis for a major policy change, I argue, and there are no new numbers yet available to see if the experiment was successful.

What do you think? Should there have been more study before your clock-changing habits were themselves changed? Do the other benefits make extended daylight time worthwhile even if energy isn't saved? How does the clock change affect your energy consumption? Please let me know in the comments.

Further reading: Rep. Upton used the 1970s-era estimate of 100,000 barrels of oil saved each day in a press release in support of the extension (as I noted in an earlier column).

An estimate of projected energy savings by the American Council for an Energy-Efficient Economy, a Washington, D.C.-based group advocating for energy efficiency, also relied on the '70s data.

Another supporting study, conducted in California, was based on a statistical simulation of demand. This study from Australia called into question the notion that extended daylight time saves energy.

The Dunn County News also recently called into question the energy-savings thesis. A joking letter-to-the editor suggesting daylight savings helps exacerbate global warming was taken seriously by some newspaper readers.