Image: Mike Licht, via Flickr
Spring forward, Autumn back… the simple way to remembering DST.
What is Daylight Saving Time?
Daylight Saving Time (DST) is the practice of advancing clocks during Summer months by one hour so that in the evening daylight is experienced for one hour longer, while sacrificing normal sunrise times.
It has been ingrained in our consciousness ever since we were young children learning to tell the time, but most of us never really truly understand why we have to set our clocks one hour ahead in the Spring and an hour behind in the Autumn.
Why Do We Have DST?
The celebrated British Prime Minister Sir Winston Churchill argued that it enlarges "the opportunities for the pursuit of health and happiness among the millions of people who live in this country". It is a sentiment shared by many.
Historically, retailing, sports, and tourism interests have favored daylight saving, and its initial adoption was prompted by energy crisis and war. During the Second World War countries experienced fuel shortages; this was being caused by the slowing down of trade. Trading ships carrying oil, gas and even food were easy targets for enemy submarines.
DST is not universally liked however. Contrary to popular opinion, DST was not created to help farmers gather their harvests – in fact many farmers are against the idea altogether, arguing that it reduces worker productivity.
One main reason we still change our clocks to DST to this day, is to save electricity. In general, energy use and the demand for electricity for lighting our homes are directly connected to when we go to bed and when we get up. Bedtime for most of us is late evening through the year. When we go to bed, we turn off the lights, TV and computer devices.
DST "makes" the sun "set" one hour later and therefore reduces the period between sunset and bedtime by one hour. This means that less electricity is used for lighting and appliances late in the day. We may use a bit more electricity in the morning because it is darker when we rise, but that is usually offset by the energy savings in the evening.
In the Winter, the afternoon DST advantage is offset by the morning's need for more lighting. In Spring and Autumn, the advantage is less than one hour.
How Can I Benefit from DST?
DST saves energy for lighting in all seasons of the year except for the four darkest months of the year (November, December, January and February) when there is no significant change. This means that this period is the best time of year to change your traditional incandescent and CFL light bulbs to energy efficient LED light bulbs. So not only can you keep your lights on for fewer hours, even when they are burning you’ll be saving money on your energy bills.
By changing your CFL and incandescent light bulbs to LED light bulbs during the Winter, you will be helping to reduce demand on the electricity grid, also resulting in fewer carbon emissions.