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Daylight Saving Time Saves 1% In Energy Costs

Fri., April 5, 1996

Q. I understood that daylight saving time saves energy. If this is true, why don’t we operate on it year round?

A. You’re right. Daylight saving time does save energy by moving an hour of daylight from the morning to the evening. The principle is simple. During part of the year, the sun rises before most people do. If the clock is set ahead, sunrise by the clock will be later (as will sunset).

The clock shift does not increase the hours of light, but it saves daylight in the sense that it shifts the number of daylight hours from when people are normally asleep to when they are normally awake, thereby reducing the need for artificial lighting during evenings.

Using daylight saving time from April to October is estimated to save the nation 1 percent in energy consumption. Maintaining daylight saving during winter, however, could increase energy use in office buildings by the shifting hours of heating use toward the cooler part of the day.

The idea was first written about by Ben Franklin in 1784 in a tongue-in-cheek article following his attendance at the demonstration of a new oil lamp. He was living in Paris at the time and calculated that Parisian shopkeepers could save one million francs on the 96 million candles they wouldn’t have to burn by switching to daylight saving time.

But it was Londoner William Willett who campaigned for daylight saving time in the House of Commons in 1907. The bill was rejected the following year.

It was not until World War I that daylight saving time was first adopted. Several countries involved in the war adopted it to conserve fuel by reducing the need for artificial light.

In 1966 Congress passed legislation making standard time mandatory and daylight saving time optional for states, and only to be observed from April to October (not year round).

The savings are greatest in the summer because hours of use are shifted toward the earlier, cooler part of the day. When shifting to and from daylight saving, it is important that building operators remember to set automatic time clocks for lighting and cooling systems ahead and back for daylight saving to assure proper performance.

Daylight saving time begins on Sunday. Remember to adjust your clocks.


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