Daylight Saving—unused solar power?

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Today is the longest day of the year in the northern hemisphere (those looking to party, hurry to Sweden, they do the solstice right up there). In London (today’s weather forecast: sunny; today’s actual weather: gloomy) campaigners are using midsummer to draw attention to what they say is one of the low-hanging fruits in the fight against climate change: daylight saving.

The Lighter Later campaign wants to re-set the clocks an hour later throughout the year in the UK (they still want the “spring forward/fall back” clock changes, but the starting point would be an hour later in both cases). They believe that lighter evenings would reduce energy usage, as people keep the lights off longer. Today they are holding an event at which Dr Elizabeth Garnsey, from the University of Cambridge’s Institute of Manufacturing will present a study arguing that extending daylight later into the evenings in October will reduce electricity demand in the UK  by .3%, amounting to a saving of  450,000 tonnes of carbon saved annually, or the equivalent of taking 200,000 cars off the road.

In Britain, both the Conservatives (who are currently in a ruling coalition with the minority Liberal Democrats) and the opposition Labour Party reportedly expressed support for a change to Britain’s daylight savings before the recent general election.  But there is no scientific consensus on whether fiddling the clocks helps reduce energy use. Other studies—including those on locations where daylight saving have been extended—offer results that contradict Garnsey’s claim (Wikipedia links to some of the major studies on this one). It seems that the connection between energy use and daylight is somewhat culturally dependent: in warm climates, for instance, people might return to a sunlit home only to turn the air conditioning unit on, as seemingly happened in California after the U.S. switched its daylight savings calender in 2007.

In Britain, of course, that’s less of a danger (no need for aircon, although a full kettle and electric heating blanket are always tempting). Far more compelling is the argument that extending daylight into rush hour will reduce traffic fatalities (by 100 deaths a year, according to Lighter Later).

Extending evening daylight—particularly in winter—is popular politically as voters become increasingly likely to live in cities rather than rural areas. So expect Britain to change its daylight savings calendar in the near future. But whether that’s a bright idea from a climate change perspective—only time will tell.