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| Fig. 1: Map of Daylight Saving Time in the US. Areas in blue observe DST. Areas in orange observe permanent standard time. (Source: Wikimedia Commons) |
The United States has officially observed Daylight Saving Time (DST) since the implementation of the Uniform Time Act of 1966. [1] Clocks are set an hour backward from standard time in the fall and an hour ahead in the spring with the purpose of maximizing sunlight exposure and minimizing energy use. The majority of states in the US observe DST with the exception of Hawaii and most of Arizona. [2] However, countries that observe DST are a minority around the world.
Historically, many famous figures have proposed adjusting the social clock to align with the sun in order to conserve energy. DST was eventually officially implemented in order to fulfill the goal of maximizing daylight and conserving energy.
Although electrical energy used for lighting is conserved in alignment with the original intent of DST, a study conducted in Indiana reports an increase in the energy used for cooling and heating [3]. Overall, the increase in energy consumption for cooling outweighs the increase in energy conservation for lighting as seen in Table 1.
In contrast, a report by the Office of Energy Efficiency and Renewable Energy (EERE) on energy consumption in the United States finds that the total electricity savings from extended DST corresponds to 0.03% of electricity consumption over the year [4]. However, the reported energy savings effect is extremely small.
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| Table 1: Changes in average daily electrical energy consumption and costs under DST (Indiana, 2006) [3] | ||||||||||||||||||||
| * 1 kWh = 3.6 × 106 J ** average cost of residential electricity service is $0.054 per kWh *** 2,724,429 households in Indiana |
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The ambiguity in the current research surrounding DST suggests that the energy savings and costs of DST are, therefore, too small to measure reliably.
DST policies are heavily debated as there are many conflicting political viewpoints and ambiguity in the scientific findings. While assessing the trajectory of permanently adopting optimal energy conservation strategies, there are many factors and consequences to consider. With respect to energy conservation, there is little concrete evidence that the original purpose of implementing DST is being fulfilled to a significant extent as the effect of DST implementation on energy consumption is too small to measure reliably.
© Lenae Joe. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Congressional Declaration of Policy; Adoption and Observance of Uniform Standard of Time; Authority of Secretary of Transportation," United States Code, 15 U.S.C. 260 (1966).
[2] J. R. Carter, K. L. Knutson, and B. Mokhlesi, "Taking to Heart the Proposed Legislation for Permanent Daylight Saving Time," Am. J. Physiol. Heart Circ. Physiol. 323, H100 (2022).
[3] M. J. Kotchen and L. E. Grant, "Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana," Rev. Econ. Stat. 93, 1172 (2011).
[4] "Impact of Extended Daylight Saving Time on National Energy Consumption," U.S. Office of Efficiency and Renewable Energy, October 2008.
