The leaves are turning brown and we’re turning our thermostats up. This can only mean one thing: British Summer Time is coming to an end, marked by the changing of the clocks. We’ve been changing the clocks for 100 years, though many of us remain in the dark about why we do it. So here’s a quick guide to the history and science of why we ‘spring forward and fall back’.
When do the clocks change in the UK?
The clocks change twice a year: forward one hour at 1am on the last Sunday in March, and back one hour at 2am on the last Sunday in October. During the summer, ‘Daylight Saving Time’ (DST) applies, while in the winter we revert back to ‘Greenwich Mean Time’ (GMT).
The months in which DST applies are also known as British Summer Time (BST).
When was Daylight Saving Time introduced?
Daylight Saving Time was introduced in 1916 in the UK.
Why do we change the clocks?
One summer morning in 1905, British builder William Willett was riding his horse through the London suburbs. He passed house after house with closed blinds, and it suddenly came to him that the morning sunlight was going to waste. In 1907 he published the pamphlet "The Waste of Daylight", which caught the attention of Parliament. Sadly Willett died of flu a year before DST became law, and never saw the fruits of his labour.
So to put it simply, we change the clocks to make better use of natural daylight in the morning. During the summer time, we borrow an hour of daylight from the morning and shift it to the evening to reduce our energy consumption.
Hang on, didn’t Benjamin Franklin come up with the idea of Daylight Saving Time?
Sort of. In 1784 the scientist and founding father of the United States published an essay called “An Economical Project for Diminishing the Cost of Light”. It argued that if people got up with the sun and went to bed earlier at night, we’d save on the cost of candles. It was somewhat tongue-in-cheek and didn’t go much further at the time.
Does changing the clocks really save us energy?
There’s conflicting evidence around this. In 2006 the US state of Indiana shifted to daylight saving for the first time. Surprisingly, this led to a 1% increase in residential electricity use, possibly stemming from increased need for air conditioning.
In 2007, US Daylight Saving Time was extended by four weeks. A California study found this had little to no impact on energy consumption. However, a national study in 2008 did report that the extension saved about 0.5% of the nation’s electricity per day, an amount which could power 100,000 households for a year.
If you want to reduce your personal energy usage, a great place to start is to learn more about your consumption patterns. Our ‘My Energy’ tools allow you to keep track of what you’re using, compare your usage to that of your neighbours and learn about the efficiency of your appliances. Just log into your online account and click on ‘My Energy’.