Are Daylight Savings Time Energy Savings a Myth?

This year, The U.S. has decided to extend daylight savings time with the intent of saving energy--an anticipated 1% decrease in electricity consumption.  A recent study out of Berkeley claims such claims are wrong.  Here's the abstract:

Rising energy prices and environmental concerns are driving countries to consider extending Daylight Saving Time (DST) in order to conserve energy. Beginning in 2007, the U.S. will lengthen DST by one month with the specific goal of reducing electricity consumption by 1%. In this paper we question the findings of prior DST studies, which often rely on simulation models and extrapolation rather than empirical evidence. By contrast, our research exploits a quasi-experiment*, in which parts of Australia extended DST by two months to facilitate the Sydney Olympic Games in 2000. Using detailed panel data on half-hourly electricity consumption, prices, and weather conditions, we show that the extension failed to reduce electricity demand. We further examine prior DST studies and find that the most sophisticated simulation model available in the literature significantly overstates electricity savings when it is applied to the Australian data. These results suggest that current plans and proposals to extend DST will fail to conserve energy.

*One of the Frontiers of Environmental Economics

Comments

[James]

Did this study take into account the fact that since the olympics was going on and there was not only more activity in the city but more people, that this could have been attributed to the increase in energy usage?

[Daniel]

James,
Yes. If you read the study you'll see that two neighboring states moved DST back: New South Wales (where Sydney is) and Victoria. South Australia, which neighbors both the other states, did not move DST. This allows them to use Victoria as the treated state and South Australia as the control. In addition, they dropped the two-week period during the Olympics. It's really a clever quasi-experiment. The paper is a an interesting read, and the main conclusions can be grasped intuitively without understanding all the technical details.

[David Jeffery]

The results of this study are heavily dependent on local conditions in the area at the time.

Daylight savings came in at the end of winter in these parts of Australia during the Olympics. And, as someone who was there, it was a particularly cold winter too.

Here's a description of the main reason for the increase in energy use found in the study:

There was a new very sharp peak in power consumption at around 7.00am each morning as Victorians got
out of bed in darker colder conditions than they were used to in August and
September and turned on extra lights and heaters and lights. So severe and
unexpected was the new early morning peak in electricity usage that the
wholesale price spiked to around 15 times its normal level as the system
initially failed to keep pace.

So the extra energy use occurred because people got up an hour earlier at a time of the year when it was still cold and dark at 7 am. Generalising the findings is dangerous unless the US proposal is to extend daylight savings so that it starts at the end of winter in areas with fairly cool climates. I don't imagine that's what's proposed.

[Daniel]

Btw, the title to this post is slightly misleading. The authors are not suggesting DST does not ever save energy (after all, in the middle of summer it certainly seems to make more sense from an energy perspective to have extra daylight at 8 pm rather than 4 am). This is not even what they attempting to investigate. They are exploring the extension of DST at the fringe: does moving DST earlier in the spring or later in the fall save energy? Their conclusion seems to highlight that the energy you save in the evening with extra daylight is pretty much lost when you have to turn on your lights and heat an extra hour early in the darker, colder spring (or fall) mornings.

[David Jeffery]

True Daniel. Unfortunately some people have latched on to this study as a reason for not introducing daylight savings into warm areas of Australia during summer (currently the warmer northern parts of Australia don't have daylight saving time at all) when it really only suggests there aren't necessarily energy savings from extending daylight savings into cooler months in cooler areas.

[Lars Smith]

There is another cost associated with DST, people forgetting to adjust their clocks. Last year one of my daughter's teachers didn't show up for class because she had forgotten about the DST change.

[Daniel]

David,
Actually, the United States IS extending DST into the end of winter by moving it 3 weeks earlier this year. It begins this Sunday. Here in DC it was 23 F (-5 C) this morning when I was walking to work at 9 am.

By the way, regarding that winter being particularly cold, the researchers control for weather in the study, so this does not impact their estimate of (non) effect.

[Mark]

I did a quick study where in I looked at the new DST and sunrise / sunset times for Buffalo NY & Edmonton Alta. I wanted to know how many days of artificial light per year a person would use if they slept 8 hours a night and got up at 7AM each morning. I wanted to see what reduction in light usage is made with the old DST, the new DST and if there was a scheme that would minimise light usage. I noted that time zones are set up to align noon with the middle of the solar day. People, however, place the middle of their day at about 3PM. I concluded that by dropping the whole DST thing and just shifting all time zones ahead by 3 hours we could align the solar day with people days. For Buffalo, this reduces the number of artificial light days per year from about 72 to 57 instead of 65 as the new DST does (a 21% reduction instead of 11%).

Depending on where you live, your mileage may vary.

Whatya think?

[Rob Metcalfe]

A similar proposal is taking place in the UK (see link below). Extrapolating previous experiements is somewhat dodgy but if there are lives saved, then there could be significant benefits beyond just environmental benefits.

http://envecon.wordpress.com/2007/01/30/back-to-the-future-to-increase-well-being-and-decrease-environmental-degradation/