Today the sun is shining during my commute home from work. But this weekend, public service announcements will remind us to “fall back,” ending daylight saving time (DST) by setting our clocks an hour earlier on Sunday, Nov. 6. On Nov. 7, many of us will commute home in the dark.
This semiannual ritual shifts our rhythms and temporarily makes us groggy at times when we normally feel alert. Moreover, many Americans are confused about why we spring forward to DST in March and fall back in November, and whether it is worth the trouble.
The practice of resetting clocks is not designed for farmers, whose plows follow the sun regardless of what time clocks say it is. Yet many people continue to believe that farmers benefit, including lawmakers during recent debates over changing California DST laws. Massachusetts is also studying whether to abandon DST.
Changing our clocks does not create extra daylight. DST simply shifts when the sun rises and sets relative to our society’s regular schedule and routines. The key question, then, is how people respond to this enforced shift in natural lighting. Most people have to be at work at a certain time – say, 8:30 a.m. – and if that time comes an hour earlier, they simply get up an hour earlier. The effect on society is another question, and there, the research shows DST is more burden than boon.
No energy savings
Benjamin Franklin was one of the first thinkers to endorse the idea of making better use of daylight. Although he lived well before the invention of light bulbs, Franklin observed that people who slept past sunrise wasted more candles later in the evening. He also whimsically suggested the first policy fixes to encourage energy conservation: firing cannons at dawn as public alarm clocks and fining homeowners who put up window shutters.
To this day, our laws equate daylight saving with energy conservation. However, recent research suggests that DST actually increases energy use.
This is what I found in a study coauthored with Yale economist Matthew Kotchen. We used a policy change in Indiana to estimate DST effects on electricity consumption. Prior to 2007, most Indiana counties did not observe DST. By comparing households’ electricity demand before and after DST was adopted, month by month, we showed that DST had actually increased residential electricity demand in Indiana by 1 to 4 percent annually.
The largest effects occurred in the summer, when DST aligns our lives with the hottest part of the day, so people tend to use more air conditioning, and late fall, when we wake up in the dark and use more heating with no reduction in lighting needs.
Other studies corroborate these findings. Research in Australia and in the United States shows that DST does not decrease total energy use. However, it does smooth out peaks and valleys in energy demand throughout the day, as people at home use more electricity in the morning and less during the afternoon. Though people still use more electricity, shifting the timing reduces the average costs to deliver energy because not everyone demands it during typical peak usage periods.