Daylight Savings Time Raises Energy Use: Study

Over the years, Daylight Savings Time (DST) has been quite controversial. Traditionally opposed by farmers and other early morning workers, as well as many in rural areas, debate has also raged for yeas about whether the practice results in more or less energy use.

Now that the world has been wakening up to the severe threats posed by emissions-induced global warming, the battle has taken a more immediate tenor.

A study published last month by UC Santa Barbara researchers found that residential energy use in Indiana went up by 1 to 4 percent during daylight savings time, as reported by the Ventura County Star.

Indiana provided an interesting test case, because until 2006, only 15 of Indiana's 92 counties were on daylight savings time. So researchers compared monthly meter readings of electricity use for millions of Indiana households before and after the change. They found that electricity use went up as a result, costing ratepayers an additional $8.6 million annually.

Why? The researchers pointed to the fact that reduced evening lighting needs seemed to be offset by people running the heat more in the resultant cooler mornings. Also, in the summer people were running their energy-hungry air conditioners more in the evenings.

This isn't the first study to look at this question. Back in 1975 the U.S. Department of Transportation concluded that DST might reduce energy use 1% during March and April, but a later review of the data by the National Bureau of Standards said that finding was questionable (note that back then lighting was less efficient, and used a greater percentage of household energy). When parts of Australia adopted DST in 2000, energy consumption stayed about the same, although increasing morning loads drove prices up. Further, a 2007 simulation in Japan predicted that overall energy use would rise if Osaka switched to DST.

A lot of city dwellers working 9-5s like DST, because it gives them more daylight hours after work with which to get outdoor chores done, socialize, exercise, and so on. Those who are naturally night owls clearly benefit from seemingly longer days. Retail and sporting industries say later light helps their sales, while farmers, theaters and broadcast TV ratings suffer.

Gasoline consumption does tend to rise after DST, something greens should be concerned about. Also, switching the clocks can complicate timing of events and processes, particularly when it comes to sensitive equipment.

The practice has mixed and unclear effects on health and safety, with some arguing it decreases depression, and others saying it can increase skin cancer. DST does seem to decrease traffic accidents and possibly some crimes, though the numbers are not overly convincing.

Regardless of whether you support DST or not, you don't have much choice in most of the country. Millions of Americans will have to turn their clocks forward an hour this weekend, as DST begins at 2 am on March 9.

What can you do to make sure you don't waste more energy than you need to? Adjust your thermostat to optimize heating and cooling for when you actually need it, and save energy when you don't. Do the same with lighting, so you aren't leaving any unnecessary bulbs burning.

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