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Belief vs. evidence: Daylight savings actually wastes electricity

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  • Belief vs. evidence: Daylight savings actually wastes electricity

    This isn't that surprising - the biggest household expenditures on electricity have nothing to do with lighting.

    In the 1700s of course there was no electricity, and air conditioning cooling was nonexistent as were washing machines/dryers and refrigerators.

    But of course Senator Markey (yes, of Cap & Trade bill fame) isn't bothered by minor considerations like facts.

    http://online.wsj.com/article/SB120406767043794825.html

    For decades, conventional wisdom has held that daylight-saving time, which begins March 9, reduces energy use. But a unique situation in Indiana provides evidence challenging that view: Springing forward may actually waste energy.

    Up until two years ago, only 15 of Indiana's 92 counties set their clocks an hour ahead in the spring and an hour back in the fall. The rest stayed on standard time all year, in part because farmers resisted the prospect of having to work an extra hour in the morning dark. But many residents came to hate falling in and out of sync with businesses and residents in neighboring states and prevailed upon the Indiana Legislature to put the entire state on daylight-saving time beginning in the spring of 2006.

    Indiana's change of heart gave University of California-Santa Barbara economics professor Matthew Kotchen and Ph.D. student Laura Grant a unique way to see how the time shift affects energy use. Using more than seven million monthly meter readings from Duke Energy Corp., covering nearly all the households in southern Indiana for three years, they were able to compare energy consumption before and after counties began observing daylight-saving time. Readings from counties that had already adopted daylight-saving time provided a control group that helped them to adjust for changes in weather from one year to the next.

    Their finding: Having the entire state switch to daylight-saving time each year, rather than stay on standard time, costs Indiana households an additional $8.6 million in electricity bills. They conclude that the reduced cost of lighting in afternoons during daylight-saving time is more than offset by the higher air-conditioning costs on hot afternoons and increased heating costs on cool mornings.

    "I've never had a paper with such a clear and unambiguous finding as this," says Mr. Kotchen, who presented the paper at a National Bureau of Economic Research conference this month.

    A 2007 study by economists Hendrik Wolff and Ryan Kellogg of the temporary extension of daylight-saving in two Australian territories for the 2000 Summer Olympics also suggested the clock change increases energy use.

    That isn't what Benjamin Franklin would have expected. In 1784, he observed what an "immense sum! that the city of Paris might save every year, by the economy of using sunshine instead of candles." (Mr. Franklin didn't propose setting clocks forward, instead he satirically suggested levying a tax on window shutters, ringing church bells at sunrise and, if that didn't work, firing cannons down the street in order to rouse Parisians out of their beds earlier.)

    During the first and second world wars, the U.S. temporarily enacted daylight-saving time as an energy-saving measure. Over time, most states began changing their clocks, and in response to the 1973 oil shock, the country extended daylight-saving time in 1974 and 1975. Analyzing that time shift, a 1975 report by the U.S. Department of Transportation concluded that the change reduced electricity demand by 1% in March and April. But in a 1976 report to Congress evaluating that analysis, the National Bureau of Standards concluded that there were no significant energy savings.

    Still, the Transportation Department study stuck. Speaking before the House of Representatives in 2002, Indiana Rep. Julia Carson said that under daylight-saving time, Indiana families would save "over $7 million annually in electricity rates alone."

    In 2005, Reps. Edward J. Markey of Massachusetts and Fred Upton of Michigan drafted legislation that would extend daylight-saving time nationwide. Congress approved the amendment, which called for clocks to be sprung forward three weeks earlier in the spring and one week later in the fall. The change went into effect last year.

    The energy-savings numbers often cited by lawmakers and others come from research conducted in the 1970s. Yet a key difference between now and the '70s -- or, for that matter, Ben Franklin's time -- is the prevalence of air conditioning.

    "In an inland state like Indiana, it gets hot in the summer," says Steve Gustafsen, a lawyer in New Albany, Ind., who filed a suit in 2000 in an effort to get his county to abandon daylight-saving time. "Daylight saving means running the air conditioner more."

    That was borne out by the study by Mr. Kotchen and Ms. Grant. Their research showed that while an extra hour of daylight in the evenings may mean less electricity is spent on lights, it also means that houses are warmer in the summer when people come home from work. Conversely, during daylight-saving time's cooler months, people may crank up the thermostats more in the morning.

    Still, the case on daylight-saving time isn't closed.

    "My read on this study is that it's one data point that gives us something to think about," says Richard Stevie, an economist with Duke Energy, of Mr. Kotchen and Ms. Grant's research. "I think that additional research really needs to be done." And UCLA economist Matthew Kahn points out that even if the evidence on Indiana is airtight, the effect of daylight-saving time on other states might be different -- a point that Mr. Markey makes as well.

    "One study of the situation in Indiana cannot accurately asses the impact of [daylight-saving time] changes across the nation, especially when it does not include more northern, colder regions," the congressman notes.

    There may also be social benefits to daylight-saving time that weren't covered in the research. When the extension of daylight-saving time was proposed by Mr. Markey, he cited studies that noted "less crime, fewer traffic fatalities, more recreation time and increased economic activity" with the extra sunlight in the evening.

    In Indiana, the debate goes on. "The simpler the issue, the more people have opinions about it," says Indiana State Rep. Scott Reske, who voted against the switch to daylight-saving time. In the aftermath of the time shift, "a lot of people who hated it now love it, and a lot of people who loved it now hate it," he says. A separate debate over whether the state should be on Central or Eastern Time rages on.

  • #2
    Re: Belief vs. evidence: Daylight savings actually wastes electricity

    There really is no purpose to DST anymore. And yes, lighting is not the biggest use of household electricity despite what many seem to believe, but it is probably the easiest way to cut back without losing comfort or utility. Turn my AC off, no way! Turn off some lights I'm not using or use more efficient lighting, no problem.

    The facts in this seem to show greater energy use during DST, but I'm not really sure why. Do not most people just set the thermostat and forget about it? If thats the case, energy use would not change one bit. But apparently thats not the case.

    Comment


    • #3
      Re: Belief vs. evidence: Daylight savings actually wastes electricity

      Originally posted by flintlock View Post
      The facts in this seem to show greater energy use during DST, but I'm not really sure why. Do not most people just set the thermostat and forget about it? If thats the case, energy use would not change one bit. But apparently thats not the case.
      I guess those of us that program our thermostats based on bedtime and wake time, while saving $, are not saving as much as we could if DST went away. And/or some change in how often people adjust thermostats during the day. ??? Ah well.

      Comment


      • #4
        Re: Belief vs. evidence: Daylight savings actually wastes electricity

        Originally posted by flintlock
        The facts in this seem to show greater energy use during DST, but I'm not really sure why. Do not most people just set the thermostat and forget about it? If thats the case, energy use would not change one bit. But apparently thats not the case.
        That's why it is important in the real world to have real data.

        This is a fantastic example - a more or less uniform population with scattered pockets of DST vs. mostly no DST, but then everyone being forced onto DST.

        The excuses about Indiana not applying to other states is a really weak one - if anything I'd expect greater impact in really hot weather states like the Southwest, or humid ones like the South. This is unlikely to be offset by likely savings in cold states like in the Northeast because 1) heating is generally not electric as opposed to cooling which is 100% electric, and 2) daylight = more heat = less relative energy use
        Last edited by c1ue; March 17, 2011, 10:16 AM.

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        • #5
          Re: Belief vs. evidence: Daylight savings actually wastes electricity

          i would guess that there are a lot of people who turn on their air conditioners when they get home from work. get home an hour later in the evening and the world has gotten a little cooler so the load is lower. you're trading an hour of late afternoon-early evening cooling for an hour of early morning cooling.

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          • #6
            Re: Belief vs. evidence: Daylight savings actually wastes electricity

            It's important to know what real data is and to draw reasonable conclusions from data.


            A more recent study - in draft form as of February 2008 - by Matthew Kotchen and Laura Grant of the University of Santa Barbara concludes that Daylight Saving Time in Indiana actually increases residential electricity demand. That study titled "Does Daylight Saving Time Save Energy? Evidence From a Natural Experiment in Indiana". (PDF file) looked at the electricity use when portions of the state finally started to observe DST. Before the new extended DST, portions of Indiana did not observe DST.

            Some have wondered whether this study would be true for the entire United States. Initial analysis by staff of the California Energy Commission says a similar study may not yield the same results for California because:

            The use of residential air conditioning is relatively low in Indiana, and the saturations are low. Where as California has high usage of air conditioning in the summer.
            Heating use is relatively high in Indiana, while it is relatively low in California.
            The diurnal variation in temperature is low while California is very high.
            Indiana is located in western edge of the same time zone as Maine and Florida, but the sun actually comes up at an earlier time than those other two states.
            Indiana's north-south location will affect how long the days are in the summer and might very well lead to different results in different areas.
            So, while the analysis is of interest to Indiana, it's conclusions may not be totally correct for California or the rest of the country. The first national study since the 1970s, was mandated by Congress and was done by the U.S. Department of Energy.

            The DOE study can be downloaded at: http://www1.eere.energy.gov/ba/pba/p...gress_2008.pdf (PDF file, 285 kb)

            The key findings in the report to Congress are:

            The total electricity savings of Extended Daylight Saving Time were about 1.3 Tera Watt-hour (TWh). This corresponds to 0.5 percent per each day of Extended Daylight Saving Time, or 0.03 percent of electricity consumption over the year. In reference, the total 2007 electricity consumption in the United States was 3,900 TWh.
            In terms of national primary energy consumption, the electricity savings translate to a reduction of 17 Trillion Btu (TBtu) over the spring and fall Extended Daylight Saving Time periods, or roughly 0.02 percent of total U.S. energy consumption during 2007 of 101,000 TBtu.
            During Extended Daylight Saving Time, electricity savings generally occurred over a three- to five-hour period in the evening with small increases in usage during the early- morning hours. On a daily percentage basis, electricity savings were slightly greater during the March (spring) extension of Extended Daylight Saving Time than the November (fall) extension. On a regional basis, some southern portions of the United States exhibited slightly smaller impacts of Extended Daylight Saving Time on energy savings compared to the northern regions, a result possibly due to a small, offsetting increase in household air conditioning usage.
            Changes in national traffic volume and motor gasoline consumption for passenger vehicles in 2007 were determined to be statistically insignificant and therefore, could not be attributed to Extended Daylight Saving Time.

            Comment


            • #7
              Re: Belief vs. evidence: Daylight savings actually wastes electricity

              Originally posted by we_are_toast
              It's important to know what real data is and to draw reasonable conclusions from data.
              Yes, that's another good data point.

              Especially this part:

              The electricity savings are small compared to the national total for the year, representing about 0.03 percent of the total national electricity consumption of 3,900 TWh in 2007.3 On a daily basis, the total electricity savings due to EDST was 0.46 to 0.48 percent per each day of EDST.
              Looking at the methodology of this study:

              • A “heuristic” method compared the average changes in the pattern of electricity consumption between 2006 and 2007 during the periods of EDST in March and November.
              • A statistical method applied regression models to daily and hourly consumption for a sample of utilities.14
              And

              observed vs model electricity profile.png

              Nearly all of the 'savings' is due to the difference in profile from observed behavior vs. a model.

              Clearly the model assumes the sharp drop at around 5 pm is due to DST, but this seems more than a little odd. For one thing, as workers commute from home to work at 9 am and then back at 5 pm, logically there should be a period of lower use. The morning spike could be explained by factories starting shifts.

              Contrast this with the Indiana study - which contrasts actual before DST and after DST profiles.
              Last edited by c1ue; March 17, 2011, 12:09 PM.

              Comment


              • #8
                Re: Belief vs. evidence: Daylight savings actually wastes electricity

                Maybe between 4:30 and 5:30, most people are using the A.C. in their cars as they commute? This nation loves its AC, you know we're getting it somewhere.

                Maybe we just have to figure out a way to keep everyone driving in their cars for a couple of extra hours! :-)

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                • #9
                  Re: Belief vs. evidence: Daylight savings actually wastes electricity

                  most of you guys are too young to remember this fandango:

                  Statement on Signing the Emergency Daylight Saving Time Energy Conservation Act of 1973.
                  December 15, 1973

                  I AM pleased to sign today H.R. 11324, placing the United States on daylight saving time for a period of approximately 2 years, beginning at 2 a.m., Sunday, January 6, 1974.

                  We have taken a number of actions to meet the energy crisis, and more will have to be taken. Many require inconvenience and sacrifice. But daylight saving time on a year-round basis, which will result in the conservation during the winter months of an estimated equivalent of 150,000 barrels of oil a day, will mean only a minimum of inconvenience and will involve equal participation by all. Unlike many of our other initiatives to deal with the energy crisis and to accomplish the goal of self-sufficiency in energy through Project Independence, these savings will not require research, new technology, diplomacy, or exploration.

                  I am delighted that the Congress has moved expeditiously in providing this method of helping to meet the energy shortage, and I am hopeful that we might see equally expeditious action on the more complex and far-reaching legislation which we must have to deal with this problem.

                  I call upon the Congress to complete action before the recess on Responsible bills to provide the energy emergency authorities we need to deal with the problem and to give a statutory base to the Federal Energy Administration to provide the necessary focused leadership.

                  Richard Nixon: Statement on Signing the Emergency Daylight Saving Time Energy Conservation Act of 1973. http://www.presidency.ucsb.edu/ws/in...#ixzz1Gt7SE0oO

                  the immediate effect I remember is kids went to school in the darkness of night, back in the day when many walked. In no time there were stories of kids getting hit by cars.

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                  • #10
                    Re: Belief vs. evidence: Daylight savings actually wastes electricity


                    RUSSIA will from next autumn stop putting its clocks back in winter, President Dmitry Medvedev says, meaning that Moscow will be four hours ahead of Greenwich Mean Time (GMT) all year round.


                    "I have taken a decision to cancel the move to 'winter' time starting from autumn of the current year," Russian news agencies quoted Mr Medvedev as telling a meeting in the Kremlin.
                    He explained the move by saying that the need to adapt to the time change each year was causing Russians "stress and illness".
                    "This really disturbs the human biorhythm," said Mr Medvedev. "It's just irritating. People either oversleep or wake up early and don't know what to do with the hour."
                    ...................
                    http://www.dailytelegraph.com.au/new...-1226002604690

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