Time Zone Report

Following Daylight Saving Time legislation in the US


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Our View

Time Zone Report believes that current research shows DST does not save energy or money spent on energy, and probably costs us more.

Prior studies showing energy savings during DST were conducted in the 1970s.  A lot has changed since then! See Cost of Owning and Operating an Automobile below.

Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana

Matthew Kotchen and Laura Grant are the authors of this detailed 36-page 2008 article available online at the National Bureau of Economic Research.  They evaluated seven million monthly meter readings in southern Indiana for three years, and were able to company energy usage before and after Indiana modified its state-wide DST choices.

The article’s abstract provides a chilling summary that goes against common perception:

Our main finding is that—contrary to the policy’s intent—DST increases residential electricity demand. Estimates of the overall increase are approximately 1 percent, but we find that the effect is not constant throughout the DST period. DST causes the greatest increase in electricity consumption in the fall, when estimates range between 2 and 4 percent. These findings are consistent with simulation results that point to a tradeoff between reducing demand for lighting and increasing demand for heating and cooling. We estimate a cost of increased electricity bills to Indiana households of $9 million per year. We also estimate social costs of increased pollution emissions that range from $1.7 to $5.5 million per year. Finally, we argue that the effect is likely to be even stronger in other regions of the United States.

Whether research in the early years of DST was wrong or that our habits have changed since the 1970s, this article clearly indicates that “saving energy” is not a benefit of DST.

This study was further reported online by The Wall Street Journal.  The WSJ article contains a brief review of some background material, then presents a few of the relevant findings.  According to the article:

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.

The bottom line from this article comes from the Conclusion section: “there is surprisingly little evidence that DST actually saves energy”.

California Energy Commission 2001 Report Says Different!

A report called “Effects of Daylight Saving Time on California Electricity Use” available online here seems to say different.  They claim that if California was to go to Winter DST (plus the usual Summer DST), they would see a drop in energy usage by 3.4 percent.

But wait… their report focuses on commercial and industrial energy usage, not residential energy, like the Indiana study.  It seems its okay to reduce power usage for companies by asking the employees to pay more for their power.

The California study also looked into “Winter DST and Double Summer DST”, setting the clock forward two hours in the spring. They concluded there would be “less savings” with this approach.  Still, see the other Areas of Concern sections for why their “Winter DST” — which is essential Year-Round DST — is a good idea for people in general.  Plus this study used data from models based on 1998-2000; a lot has changed in 15 years, though it might not quite be time to throw this one out yet.

Cost of Owning and Operating an Automobile

Some statistics regarding energy consumption and cost can be construed as positive or negative, depending on a variety of viewpoints.

For example, US DOT statistics show the Average gasoline cost per mile increased from 4.8 cents in 1975 to 13.0 cents, though gasoline cost as a percentage of total cost actually decreased, from 33.4 percent to 22.0 percent.  This is because the overall average cost per mile — which includes fixed costs of insurance, registration, taxes, etc. — was 14.4 cents per mile in 1975 (in 2013-adjusted dollars), but in 2013 had risen to 59.2 cents per mile.

1 Comment

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  1. RE: Energy

    Another paper you may wish to read is “Impact of Daylight Saving Time on Residential Energy Consumption and Cost”, Energy and Buildings (journal), vol. 25, pp. 63-68, 1997. I know the author fairly well. 🙂

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