Saturday night marks the end of daylight-saving time for 2012. Time for those clocks to "fall back" an hour to standard time, when the sun really is highest at high noon.
An extra hour of cold, dark fall mornings is probably the last thing you look forward to when you first wake up—or when you're driving to work, dropping off your children at school, or walking the dog. Similarly in mid-March, when we first "spring forward." So why do we suffer through this?
Supposedly, to save energy. Some 225 years ago, Benjamin Franklin observed that people wasted daylight in the summer, sleeping through dawn's early light and burning candles to illuminate the night. If people would only move their schedule up an hour, they would save energy, he reasoned.
Laziness being part of human nature, nobody wakes an hour earlier unforced. So, during the crises of two world wars, governments around the world adopted variants of daylight-saving time to trick people into getting up earlier by moving the clocks forward.
The United States adopted the annual use of daylight-saving time permanently in 1966, then lengthened its duration on the calendar in 1986 and again in 2007. For the past five years, an extended daylight-saving period has begun the second Sunday of March and ended the first Sunday of November.
The extension of daylight-saving time was brought to you by the same federal government that banned incandescent light bulbs. But at least that measure has a claim to saving energy. No such claim can be made for the added daylight time.
It is a fallacy to think that if something is good, then more of it must be better. In early November or mid-March, few people—college students excepted—are still sleeping through morning daylight. A household waking at, say, 6 a.m. and going to bed at 11 p.m. won't experience any more daylight when its schedule is moved up an hour, to 5 a.m. and 10 p.m. No daylight wasted, no daylight to be saved.
So the extension of daylight-saving time gives us cold, dark mornings without the energy savings to compensate. Often it actually causes us to expend more energy: Even in my Atlanta home, for the past few weeks we've turned the heat on in the early-morning hours. The effect must be even more pronounced in colder climates.
Amazingly enough, the case for daylight-saving time isn't clear-cut even in the summer months. Clever as he was, Benjamin Franklin didn't anticipate the eventual importance of air conditioning, a much more expensive item than lighting. Thanks to daylight-saving time, in the summer people come home from work an hour earlier and crank up their air conditioner in the hottest part of the day.
In 2006, some Indiana counties that had previously opted out of daylight-saving time were forced by state law to adopt it. The measure provided an opportunity to compare how energy use changed in those counties after the imposition of daylight-saving time. It also provided a ready-made "control group" of nearby counties that had been using it for years.
Profs. Matthew Kotchen of Yale University and Laura Grant of the University of Wisconsin-Milwaukee found that daylight-saving time increases energy use by over 1% in Indiana during those months—adding some $9 million to energy bills annually, plus sending an additional 188,000 tons of carbon dioxide into the atmosphere. Daylight-saving time imposes the greatest costs in the fall, the researchers found, when it prompts increases in morning heating without any savings on lighting. But it also imposes high costs in July and August, when increased air-conditioning bills more than offset the savings in lighting. Another study found similar effects in Australia.
One could argue that long summer days are a social good and well worth the energy and environmental costs. But making that argument means recognizing that daylight-saving time is no win-win proposition.
This is especially so in the earliest and latest weeks of the extended daylight-saving period. It is November—clocks should have fallen back long before now.
Mr. Banzhaf is an associate professor of economics at Georgia State University and senior research fellow at PERC.
A version of this article appeared in The Wall Street Journal on November 2, 2012, on page A11 in the U.S. edition.