In a 1784 letter to the editor of the Journal de Paris, Benjamin Franklin, then the U.S. Minister to France, satirically suggested that Parisians could improve their productivity and save money on candle wax by synchronizing their lives more closely to the sun during the summer months.
According to Franklin’s calculations, if Paris woke up at sunrise “in the six months between the 20th of March and the 20th of September” the city could save 64 million pounds of candle wax per-year. To make this happen, he proposed, among other things, that “guards . . . be posted to stop all the coaches, etc., that would pass the streets after sunset, except those of physicians, surgeons, and midwives,” and that “as soon as the sun rises, let all the bells in every church be set ringing; and . . . let cannon be fired in every street, to wake the sluggards. . . .”
Somehow, Franklin’s silly joke about saving energy by shifting the working hours of the day eventually developed into the very serious (and very annoying) practice of arbitrarily changing time twice a year: Daylight Saving Time (DST). I don’t know if Franklin would have been amused or horrified to learn that his countrymen would eventually be dumb enough to do what he only joked about.
Anyway, since the purpose of DST is to save daylight, I thought it might be useful to calculate its effectiveness. I wrote a little Python script to iterate through 2025 day-by-day and figure out the sunrise and sunset times at Washington Dulles International Airport under three possible time systems: the current DST system with biannual time changes, permanent standard time with no time changes, and permanent DST with no time changes.
The results are stunning:
ANNUAL TOTALS:
Current (with DST): 4449.56 hours of daylight
Standard (no DST) : 4449.56 hours of daylight
Permanent DST : 4449.56 hours of daylight
DAYLIGHT SAVED:
Current (with DST) vs. Standard (no DST) : 0.0
Current (with DST) vs. Permanent DST : 0.0It turns out that the amount of daylight per year doesn’t change. It’s almost as if the Earth’s rotation and orbit are not affected by our clock changes! Amazing!
Download the script (ZIP; contains .py script; requires astral & pytz)