# The Trouble with Time

23 October 2011
The end of October is creeping up, and as with every year since 1916 the clocks will change. In the UK (along with the most of the European Union) clocks go back one hour on the last Sunday in October and forward by one hour on the last Sunday in March.

This year clocks will go back one hour at 2am on Sunday 31st October in a return to Greenwich Mean Time.

But why do the clocks change? Can we use maths to help explain the benefits and drawbacks of a clock change?

The History

In 1907 a campaign began by an Englishman, William Willett, to change the clocks to avoid ‘wasting daylight’. He wanted them put forward by 80 minutes, in four moves of 20 minutes at the beginning of the spring, and back to Greenwich Mean Time in the autumn.

It took until Act of Parliament in 1916 for Summer Time to be defined – as one hour ahead of GMT from spring to autumn.

The Benefits: Some examples

Energy
The theory is that, by moving clocks forward one hour for the summer, there are more hours of daylight before people go to bed. So residential energy use (for lighting) is reduced. This of course is only true if the additional use of lighting in the morning (to account for the sun rising later) is less than that saved in the evening.
Various studies have shown different percentage savings in different parts of the country.

Economic Effects
People are more likely to be outdoors in the longer, lighter evenings. Shopping, using leisure facilities and spending money all contribute to the economy.

Public Safety
Some studies have shown a reduction in traffic accidents during Daylight Saving time, putting the reduction at around 2%.

The Drawbacks: Some examples

Daylight Saving Time can adversely affect workers whose activities are set by the sun, for example, farming.

It is claimed that the UK is missing out on income derived from Tourism by putting clocks back in Winter (much of Europe is an hour ahead of GMT in winter).

For more northern areas of the UK, it can be dark until late in the morning.

So why is using Maths here important?
The arguments for clocks staying the same and changing are both backed up by numbers and calculations. If you want to change government policy using Maths gives your argument some strength.