I visited my grandmother this past weekend, and on Sunday, found her eating lunch at 10:30 a.m. As she proudly told me that she had changed her clocks for Daylight Saving Time (DST) before she went to sleep, I realized that she had set her clocks forward an hour instead of backward. While this simple mistake was easy to fix, it did get me wondering: is DST worth the confusion?
Most people think DST was created to give farmers more daylight to work in the mornings, but it was actually created in 1966 to help reduce electricity use in buildings, and was extended again in 2005. Two studies published in 2008 examined the effect of DST on energy usage, and came up with differing results.
In the first study, from the National Bureau of Economic Research, researchers compared data from Indiana in 2006, the first year of statewide DST there, to the previous year’s energy consumption. The report found that energy consumption actually increased by one percent from March to November. Electricity use stretched up to four percent higher in the later months of the year. Although the electricity used by lights decreased, energy consumption for heating and cooling systems—which are less efficient and consume more energy than lights—increased, and raised overall electricity usage.
The next study, published by the U.S. Department of Energy, looked at nationwide data from 2007, when DST was extended to start three weeks earlier and end one week later. Researchers examined energy usage in March through November. The results showed that in 2007, 1.3 terawatt-hours were saved during DST, which corresponds to a decrease of about 0.03 percent of electricity compared with the previous year. “That amount could power 100,000 households for a year,” states an article in Scientific American.
These differing results illustrate that measuring the impact of DST on energy consumption is a very difficult problem. There are so many variables to consider, and surprisingly few studies have been conducted.
Without more studies that control for as many variables as possible over the entire DST period, it is hard to justify whether or not DST is worth the confusion. In the meantime, I’ll make sure to let my grandmother know that for the next time change, she should “spring ahead.”