So why have we decided to extend Daylight Saving Time (DST) by a month in 2007? The stated goal is to cut electricity consumption by 1%. General consensus has it that a large percentage of energy is consumed by lighting and appliances when people are at home in the evenings. By extending evening daylight an hour, one can conclude that less lighting will be used and people will spend more time outdoors thus saving electricity.
What kind of evidence do we have to support this common knowledge? Well, not much. The last major study done in the U.S. was conducted in the 1970's and based its conclusions largely on simulations rather than any empirical evidence. California also engaged in a smaller study in 2001, but it suffers from the same assumptions as the 1975 study. The best empirical study we have comes from Australia's 2000 experiment with early Daylight Saving Time. Surprisingly, the results of Australia's early DST experiment fail to show any energy savings at all.
UC Berkley's Ryan Kellogg and Hendrik Wolff recently wrote a report for the Center for the Study of Energy Markets (CSEM) that uses data from the Australian 2000 DST move to examine the energy savings motive behind the U.S 2007 early DST legislation. Their fascinating study finds that the 2000 Australian DST move actually led to higher energy consumption as morning peak load increased more than offsetting decreases in the evening.
While we applaud our politicians' energy saving intentions, we need to continue to support responsible academic research that can provide them with the type of data they need to make informed decisions. That said, I guess when you don't want to get out of bed Monday morning thanks to the time change, you can take solace in the fact that you're doing it for what people at least want to believe is a good cause.