Tuesday, October 17, 2006

Doing the Math

I'm a person who enjoys my maths. Rather than think "What are the chances of that?" i'm more likely to work out the answer. Sometimes in supermarket queues i'll decide to calculate just how much difference is there between 16 for $9.98 and 11 for $7.

So everyone knows that these new-style light bulbs save power ... and therefore save their owners money. But i wondered how much that is.

Reading on the pack that these things last 6000 hours (six times the old-style bulbs) i decided to base my calculations on that. So for both styles, i totalled the bulb cost and the electricity cost (as shown below).


As you can see, it is a significant saving, at close to $40. Of course this assumes a lifetime of 6000 hours (some brands claim 10,000). Also it assumes a constant price of electricity. Obviously, a longer lifetime / higher power price would increase the saving even further.

Buy the way, i did a calculation on how long it would take the new-style bulb to 'pay itself off'. The answer is less than 800 hours. For a bulb in common use, this is less than 5 months. After that, it's pure savings!

UPDATE: Now in 2012/13, the $40 saving is now over $70 at current electricity prices.

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