By Brian Merchant, TreeHugger
Ever since being implemented in the early 1900′s, considerable controversy has surrounded the use of Daylight Saving Time. The practice benefits sports, retail (the extra daylight after the end of working hours means more shopping), and leisure activities reliant on sunlight. But it causes problems for farmers, who must work after morning dew dries, and the entertainment industry, which loses primetime viewers.
Yet Daylight Saving Time has remained seemingly debate-proof, thanks to its most important contribution: it saves energy. But this no longer seems to be the case–and instead, it could be increasing worldwide energy demand and costing billions of dollars every year.
Daylight Saving Time Saves Energy?
The foremost rationale behind DST has always been energy conservation–from sparing coal usage for incandescent lighting in the 1910′s to conserving oil during the embargo in the 1970′s. The underlying logic seems to make sense: more daylight hours, less electricity needed for lighting. Daylight Saving was even extended in 2007 under the pretext that it saved energy–whether people liked it or not.
But a 2008 study from the University of California Energy Institute revealed that there’s actually very little evidence to suggest DST saves any energy at all.
A Natural Experiment in Indiana
The study takes its data from a natural experiment done in Indiana, which provided information on residential energy consumption. From this, the study’s authors were able to “provide the first empirical estimates of DST effects on electricity consumption in the United States since the mid-1970s.”
It’s an in-depth statistical analysis of a vast set of Indiana residents’ electrical bills:
Focusing on residential electricity demand, we conduct the first-ever study that uses micro-data on households to estimate an overall DST effect. The dataset consists of more than 7 million observations on monthly billing data for the vast majority of households in southern Indiana for three years.
The main finding? Daylight Saving Time actually increases electricity demand, instead of lessening it. DST caused electrical demand to rise almost 1 percent each year overall–with a much heavier increase of 2-4 percent in the fall, when residents “fall back” an hour.
The Cause and Cost of DST’s Increased Electrical Demand
The culprit is most likely a tradeoff between the reduced demand for lighting and an increased demand for heating and cooling–and it’s a trade that DST is on the losing end of. (TreeHugger has reported similar findings.) While supposedly conserving electricity for lighting, DST is requiring even more energy for heating and air conditioning–around $9 million more. That’s right, the study estimates DST actually costs Indiana residents $9 million a year. And the kicker? The study projects the effect is even more pronounced in other areas of the US and the world. That could easily amount to billions of dollars a year spent on unnecessary energy consumption.
As the study points out, Daylight Saving is practiced in 76 countries and affects around 1.6 billion people. If indeed it turns out that it’s causing needless energy consumption–eradicating the long held convention could spare countless pounds of greenhouse gas, and save economies around the globe considerable strain.