Daylight saving time – what it is and how it works?

Since last week, we have started summer time/ daylight saving time (DST) here in Melbourne. Coming from a country where we stopped DST from maybe 30 years ago, I wonder – what’s DST and why (the hell) do we need it!

What is DST? Well the answer can be easily found on Wiki here. In short during summer time, the clock needs to be adjusted by 1 hour – my 8AM today in non DST all of sudden becomes a 9AM tomorrow in DST.

Now this hour actually caused me some pain. The most common one I share with everyone else is – that point of time when I naturally wake up all of sudden become a hour late during the day… Why the hassle?!

The popular theory is that using DST can save energy. It took some time for my very simple mind to understand how it works. To start with, let’s have a look at this picture (from Wiki). The purple in the middle shows how DST works in summer.

Greenwich_GB_DaylightChart.png

 

Let’s look at 2 situations. Say I go bed every day at 10:30 and get up at 6:30.

  • April when daytime starts to increase
    • If there is no DST, the sunrise = 6:00 and the sunset = 18:00. My total usage of energy (electricity for lightening in particular) = 4:30 hours.
    • If there is a DST, the sunrise = 7:00 and the sunset = 17:00. My total usage of energy = 4 hours.
    • That’s a saving of 30 mins/ family.
  • July when daytime is at max
    • If there is no DST, the sunrise = 4:00 and the sunset = 20:00. My total usage of energy (electricity for lightening in particular) = 2:30 hours.
    • If there is a DST, the sunrise = 5:00 and the sunset = 21:00. My total usage of energy = 1.5 hours.
    • That’s a saving of 1 hour/ family + in the morning we gain 1 hour of productivity (in DST, I only sleep for 1.5 hour after sunrise vs in non DST, I sleep for 2.5 hours after sunrise).

So in short during DST time, it increases productivity and reduces electricity usage…. theoretically. It all sound rosy, but does it really work?

I’ve read some reports which shows that the saving of electricity is minimum from DST (search ‘does DST work’ in google). Again, in my very simple mind, I think it’s because the overall usage of electricity is so big hence the savings from lightening becomes almost nothing, plus with the advance of technology, we’ve got lots of energy saving bulbs, which further reduces power consumption. Saying that though, I don’t doubt when this policy first started, it did the job… like100 years back.

The dilemma is, as much hassle it is for individuals to adjust to DST these days, it’s is the same hassle for the country to cancel DST. If you think how many systems are already set up with that setting, and how many schedules are made in that way. Making those changes cost money and resources so unless there is a clear gain to do it, it will be on the bottom of the list from whatever government and we will need to… just live with it.

Above is just some of very light touch on this topic. Leave it in the comment and happy to discuss further!

Advertisements

6 thoughts on “Daylight saving time – what it is and how it works?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s