The horror of daylight savings (sorry Perth)

October 25, 2006

I have friends in Perth, who I have always envied for the fact that they don't apply daylight savings there.

For anyone who somehow has no idea what I'm talking about… because the days are long in the summer, many countries in the world apply 'daylight savings', to effectively shift an hour of daylight from the morning (when people are typically still asleep) to the evening (when people are still able to work). When winter comes around again, they adjust back to 'normal', and have a day centred around noon again.

Personally, I wish the world would just say "Hey, it makes much more sense for us to be centred around 1pm. The working day (9am-5pm) is centred around 1pm, so let's make our timezone match that being the time that the sun is at its highest too." Then we could abolish daylight savings. It might make for winter mornings when the sun doesn't come up until after we're at work, but how is that much different to having the sun go down at 4pm? Much easier if you live near the equator and have days that much more consistent in length. I have a cousin who lives in the Shetland Islands, where at Christmas the sun doesn't quite come up even at noon.

And now Western Australia (the state that contains Perth) is looking to introduce daylight savings. Of course, much of the population is rejoicing. They want to have the hour of daylight shifted from the morning to the evening. They don't want to be woken up by the sun streaming through their windows at 5am – they'd much rather have it stay up until 8pm in the evening.

But pity all the people who ever use computers, and have no idea of the luxury they've always had by not having a timezone adjustment.

Oh I know… Windows is really good this way and will adjust your timezone for you twice a year. Microsoft even bring out patches to fix up Australian computers when the government decides to change the system for the Olympics or Commonwealth games. I'm sure Microsoft will roll its collective all-seeing eyes and produce a patch for Perthites. If not, Michael Kleef will write one himself!

But what does this mean for all the code that was written without considering daylight savings? Surely the fact that you never hear whinges from developers in the rest of the world about daylight savings?

Well, you actually do. It's one of those things that people just live with. But the nightmares caused by daylight savings are many.

So, consider the situation where your server changes timezones. You might have a 2-minute-long event which started at 00:59 and ended 02:01. Or which started at 01:59 and ended at 01:01. Does your code handle that? Do your clients mind if you're working around the clock on something but the timeline suggests you all took an hour off in the middle of a crisis?

Or, consider the situation where your server doesn't change timezones. People start whinging that 'current time' is displayed wrong on the web server. So you translate everything into the user's timezone, but now when they look for that event that occurred at 5pm on a particular day 6 months ago, they can't find it, because they've changed timezone since then and the history figures it must've happened at 4pm.

What happens to the overnight staff who work for that extra hour in Autumn/Fall, or work an hour less in Spring? Do you pay them for that time? The system says they clocked in at 10pm and left at 8am, same as always… Or else they actually have worked an extra hour and break various industrial relation laws. Not to mention the disgruntled person who feels that they've been forced to work an hour less…

People typically make the decision one way or another and just live with it. But poor Perth – they had the luxury of avoiding daylight savings, and may find it forced on them.

This Post Has 22 Comments

  1. robfarley

    Actually there’s more.

    Suppose you have a process scheduled for 1:30am. That time might never occur. Or else, it might occur twice (will that break your system?)

    Suppose you have a system which needs to complete before staff members arrive for the day. You can easily force your servers to use the same timezone all year round, but you’ll never get your staff to…

  2. Martin

    I think the issue around daylight savings was initially aimed at farmers and schoolchildren. It was based on safety to try to have the daylight in the morning when they were going to school and, because they finish in the afternoon before we all finish work, the early nights were not an issue. The safety issue always seems to crop up whenever daylight savings is discussed. I have also seen mention of moving the clocks permanently to the summer-time setting all year round – which also seems to get shot down because of safety concerns.

  3. robfarley

    Actually it started during the war, because people needed better use of daylight hours.

    The safety issue gives a reason to move back to winter time, but it all comes down to when you want the hour to be. Because the school day is centred around 12, it suits kids to have winter time.

    I do appreciate that it’s popular with people. It’s just a pain for anyone who needs to have IT systems that handle it.

  4. Paul Stovell

    The whole time thing is screwed. Why do we even need time zones in the first place?

    Consider this: It’s 1AM in London. At that same moment, it’s 1AM in Sydney. It’s also 1AM in New York.

    What would be the problems with that?

    In Sydney, our working day might start at 5PM and finish at 1 AM (when it’s light and day). In London you’d start work at 3AM and go home at 11PM. What’s the problem? You’d hear a bunch of people coming back from London telling funny anecdotes that they used to wake up at 3AM to go to work, but that would pass after a couple of years.

    What would be the benefits?

    Computer systems would always work no matter what the timezone is. You’d never need to worry about “daylight savings” – that would just involve people leaving for work at 6PM instead of 5PM. It would be as if everyone ran off UTC time.

    The current time system is like Imperial measurements. It’s time we came up with a Metric time system!

  5. Matt Hamilton


    Love the idea of a metric time system! I’ve been waiting a gigasecond for someone to come up with that!

  6. Matt Hamilton

    heh – I was a member of an open source project ( once that tried using Swatch Time as its time measurement. They soon switched back to UTC. πŸ™‚

  7. robfarley

    Yup. It’s nasty.

    You know, one of the problems with UTC/GMT is that many people consider that London is always GMT, but it’s not. For half the year they’re GMT+1. So Aussies who know that for half the year they’re 11 (11-0) hours ahead of London, and half the year they’re 9 (10-1) hours ahead, get confused when you suggest that their timezone is GMT+10.

    Although, PCs have helped this a bit, by listing “GMT+10 (Sydney, Melbourne)”

  8. draughtrider

    I hate it when DS sneaks up on you.

    This weekend we are planning a significant upgrade of a complex legacy cluster system, with very restrictive outage windows. It’s a 20 hour process with ugly backouts if things go wrong. They had all the timings down pat. Then somebody mentioned “hey, remember we lose an hour …” … bah …


  9. Bronwen

    Yay Queensland…for now anyway

  10. Cutty

    Aw get over it guys.

    I for one am glad that the sun now comes up an hour later. I was getting a little fed up with the birds waking me up at 4:30am when the light first hit their nests.

    I only hope that Steve Bracks’ push to start DS at the beginning of October catches on.

  11. robfarley


    But don’t you think it would be easier if Melbourne stayed at GMT+11 all year?


  12. Kelly

    I live in Perth and i hate daylight saving. I am not going to set the time to daylight saving even if it’s passed because i can live on my own time quite happily, thanks.
    I mean, nature sets time, so even if parliament changes it, they don’t really, because time just keeps going on without interruption.

  13. robfarley

    Very brave of you, Kelly. πŸ™‚

  14. Jax

    The implications for e-systems are a giggle. Anyone know what day it ends so I can patch my time zone?

  15. Chris Round

    so is microsoft actually releasing a patch to give perth/WA a daylight savings upgrade?

    obviously we can just change our computer clocks, but any reference to other countries will be incorrect.

    i for one welcome the trial …. because that is what it is. maybe after 3 years it is a load of crap and people dont want to adjust – so nothing happens – or after 3 years everyone loves finishing work and going to the beach …. who knows!

  16. Joshua

    Beh, DST doesn’t really effect me, but the only thing I really hate about it is changing the clocks :P.
    But Cutty makes a really good point there, a trial is a trial, thats what it’s for TO TRIAL something.

  17. blah

    i highly recommend you stop using the computer and get a life after 6.00pm -oh my WHAT a nightmare when your computer clock isnt the right time!! go to the beach and chill out, you need it!

  18. mike

    daylight savings is good all you people that don’t think its good are just worried about your stupid computer times

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