Daylight Saving Wastes Energy, Study Says

sun.jpgI have been asked this question about daylight saving time (DST) many times. I have long believed it was not an energy saver — even though that is how it is typically justified. Turns out there is quantitative proof.

For those who are interested in this relatively obscure issue — I doubt Congress would change DST on the basis of this or any other study — you can read a very good article in the Wall Street Journal. “Springing forward,” as we will do March 9, “may actually waste energy”:

Up until two years ago, only 15 of Indiana’s 92 counties set their clocks an hour ahead in the spring and an hour back in the fall. The rest stayed on standard time all year, in part because farmers resisted the prospect of having to work an extra hour in the morning dark. But many residents came to hate falling in and out of sync with businesses and residents in neighboring states and prevailed upon the Indiana Legislature to put the entire state on daylight-saving time beginning in the spring of 2006.

Indiana’s change of heart gave University of California-Santa Barbara economics professor Matthew Kotchen and Ph.D. student Laura Grant a unique way to see how the time shift affects energy use. Using more than seven million monthly meter readings from Duke Energy Corp., covering nearly all the households in southern Indiana for three years, they were able to compare energy consumption before and after counties began observing daylight-saving time. Readings from counties that had already adopted daylight-saving time provided a control group that helped them to adjust for changes in weather from one year to the next.

Their finding: Having the entire state switch to daylight-saving time each year, rather than stay on standard time, costs Indiana households an additional $8.6 million in electricity bills. They conclude that the reduced cost of lighting in afternoons during daylight-saving time is more than offset by the higher air-conditioning costs on hot afternoons and increased heating costs on cool mornings.

“I’ve never had a paper with such a clear and unambiguous finding as this,” says Mr. Kotchen, who presented the paper at a National Bureau of Economic Research conference this month.

A 2007 study by economists Hendrik Wolff and Ryan Kellogg of the temporary extension of daylight-saving in two Australian territories for the 2000 Summer Olympics also suggested the clock change increases energy use.

And you can find that Australian study here — it concludes “These results suggest that current plans and proposals to extend DST will fail to conserve energy.” Wikipedia lists a bunch of other studies on DST, most of which (but not all) come to a similar conclusion.

Hopefully extra evening sunlight has other benefits, like “less crime, fewer traffic fatalities, more recreation time and increased economic activity.” Hopefully.

10 Responses to Daylight Saving Wastes Energy, Study Says

  1. Beefeater says:

    Once again Arizona is in the lead on this nonsense. Now if SRP could just figure out what to with all the water that they have been releasing from our reservoirs this winter. I guess they’re making room for the record snow pack to melt this spring.

  2. David B. Benson says:

    You believe anything you read in WSJ?

  3. Paul K says:

    I contend that daylight savings is essential to twilight golf and must be preserved no matter what the consequences.

  4. John Mashey says:

    David: re WSJ:
    It is wrong to dismiss the reporting is often excellent.
    Just skip the OpEd.

    We had a long discussion over in Deltoid, ,
    but see especially #8 by a well-informed commenter. I’ve had a fair number of email conversations with reporters there, who seemed quite sensible.

    Also, in the space of days:
    a) WSJ editorial offered one of their usual “AGW is a hoax” rants.

    b) WSJ news offered a straightforward story about the increasing wine production and quality of the British Columbia Lake Okanagan area due to multi-decadal warming. As a frequent visitor to that area, I can attest to that.

  5. Steven Kimball says:

    I don’t understand how air conditioner use is affected by DST since most usage takes place neither in the evening nor in the morning, but in the middle of the day, which is unlikely to be affected by an hour shift in time.

  6. Dan G. says:

    To keep in perspective the article quotes a source as saying the results would probably not apply to northern states. It is only in the higher latitudes where DST has a significant impact on many aspects of life. Simple math shows electrical usage increase due to DST (in Indiana) is around 1% annually? For Northerners, it may be worth it. Someone be pleased to check my math.

  7. RhapsodyInGlue says:

    The contention about air conditioners would seem to make sense to me for modern professional life. You work in an office during the hottest part of the day with the A/C off at home. During daylight savings the house has had 1 hour less time to cool down when you arrive home and start using A/C.

    Speaking hypothetically, given that I live in Southern Cal, in a 1922 house with no A/C.

  8. The more important point is the enormous waste of energy via air conditioning due to air conditioners being used even when the air temperature is not that high, and the old “you need a sweater in the supermarket in July” effect.

    If you removed artifacts from unnecessary air conditioner use, the study might show different results.

  9. Jimbo says:

    There is no benefit at all to daylight saving in tropical or equatorial regions. That’s the bit the DS enthusiasts seem to be unaware of. If we were to set the clocks forward during summer in Delhi; Darwin or singapore… most people would then be getting up for work in the dark.

    Daylight saving may be advantageous to temperate regions (and maybe slightly in sub-tropical regions but not to the same extent) but it isn’t right to make a sweeping statement implying that daylight saving saves energy based on a study done in one location.

    Good article BTW.

  10. I never thought for one moment that Day light savings would have been beneficial to saving on energy, how would it considering now we would be using more during these extra hours, than what we would have not having those extra hours.

    Great article and will be visiting this blog agaig