Permanent Daylight Saving Time

The U.S. Senate passed The Sunshine Protection Act by unanimous consent on Tuesday March 15, 2022. The focus of the act is to eliminate the much-maligned bi-annual switching of the clocks forward and backward by keeping the clocks on Daylight Saving Time (DST) all year. It is important to note, short of passing a declaration that puppies are cute, the Senate could pass very few bills unanimously.

Most people outside of the energy business focus on the sun rising later in the morning or setting later in the evening during DST. For those of us in the energy business who must work with hourly and sub-hourly data, the shifting of time stamps causes no small amount of agita and consternation. Consequently, the prospect of avoiding this difficulty is a welcome possibility.

The following figure shows the approximate sunrise and sunset times for Bangor, Maine and Lexington, KY for every day during 2024 under the assumption of permanent DST, which means the winter months that had been on Standard Time are now 1 hour later. There are a number of salient points to observe.

First, time zones cover a vast east-west distance, resulting in dramatically different sunrise and sunset times for locations at the extremes. In the winter, the sunset times at these two locations differ by nearly 1.5 hours, and the same can be said for sunrise times in the summer. In other words, the clocks in Bangor and Lexington display the same time, but people’s lived experience of “the day” in those locations may be quite different.

Second, shifting to permanent DST will result in the sun rising later in the winter (formerly Standard Time) months. At one point during the winter, the sun rises at nearly 9:00 a.m. in Lexington and at about 8:15 a.m. in Bangor. Consequently, many children in the continental U.S. will be going to school in the dark. But, Alaska and countries at extreme northern latitudes have always dealt with that issue.

Third, if this does become law in the U.S., it is highly likely that Canada would follow suit. It is less clear if other countries around the globe would also walk the same path.

From the perspective of electricity consumption, the result will be more lighting load in the morning, and less in the evening, as the sunset will be delayed (as measured by the clock and human behavior). The net effect on total electricity consumption is unclear and will require a deeper dive.

For the sake of all the electricity load forecasters, I hope the U.S. springs-forward for the last time.