Does daylight saving time result in lower energy bills?
For over 100 years, the U.S. and other countries have been toying with time — moving the clocks forward an hour each spring to accommodate daylight saving time, before setting them back again each fall. And for decades, politicians have been pushing to end the practice.
Earlier this month, U.S. Sen. Marco Rubio, a Republican from Florida, reintroduced the “Sunshine Protection Act,” which would do away with the “standard time” that takes place between November and March in favor of making daylight saving time permanent. For those in New York City, for example, that would mean a sunrise around 8:20 a.m. and a sunset around 5:30 p.m. on the shortest winter days. The Senate unanimously passed the bill last year, but it faltered after the House failed to take it up.
The Sunshine Protection Act lists a number of reasons for “locking the clock,” among them economic benefits, less stress, and a potential reduction in car crashes and seasonal depression. In a statement to Bloomberg Green, U.S. Sen. Ed Markey, a Democrat from Massachusetts and co-sponsor on Rubio’s bill, cited one more motivation: “Brighter skies in the winter evenings will help keep the light switch turned off and cast rays of sunshine and warmth into homes and onto Main Streets of every community in our country.”
The notion of keeping the lights off for longer has always been linked with daylight saving time. Move the clock forward by an hour in the spring, and people getting more evening sunlight will use less electricity at night — at least in theory. Benjamin Franklin is credited with first proposing changing the clocks in the 1700s as a way to conserve candles. During World War I, the U.S. and dozens of other countries enacted the policy as a wartime measure to conserve energy. By the end of the century, it was routine.
But more recently, research has emerged to challenge the DST premise. “It’s often taken on faith that it actually saves energy,” says Matthew Kotchen, an economics professor at Yale University. “In the last 10 or 15 years, a few studies have come out to question whether or not that is true.”
In 2008, the U.S. Department of Energy released a report assessing a 2005 change that extended daylight saving time by moving the “spring forward” from the first Sunday in April to the second Sunday in March and pushing the “fall back” from the last Sunday in October to the first Sunday in November. The report found that the change resulted in a 0.5 percent reduction in total electricity for each day of the extension. Most of those savings came in the evening, which offset a modest increase in electricity usage in the morning.
Other studies have struggled to identify even a moderate impact. Also in 2008, researchers published a report in the Journal of Environmental Economics and Management looking at states in Australia that had started daylight saving time two months earlier than normal to accommodate the 2000 Olympic Games. Indeed, once the clocks sprang forward, sunset came later in the day and people used less electricity in the evening. But the researchers found that increased demand for lighting in the darker mornings canceled out that effect.
In a separate study, Kotchen worked with Laura Grant, now an assistant professor of economics at Claremont McKenna College, to research daylight saving time in Indiana from 2004 to 2006. They found that the time change increased residential electricity usage as much as 1 percent. As in previous studies, the report found less demand for lighting at night, but electricity demand caused by heating (during cooler mornings) and cooling (during hotter evenings) more than offset those savings.
“If you extrapolate those results from Indiana and say how they would apply to the country as a whole, then it would suggest that from an energy perspective, daylight saving time is not a pro-environmental policy,” Kotchen says.
The latest iteration of the Sunshine Protection Act doesn’t present DST as such. A onepager of the bill briefly mentions reduced energy usage, and cites the 2008 Department of Energy study, but it also notes that research has “shown that the energy savings are minimal.” Instead, Rubio focuses on a more basic objection to springing forward and falling back: “This ritual of changing time twice a year is stupid.”