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Topic Title: Trying to work out costs
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Created On: 03 February 2014 09:18 AM
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 03 February 2014 09:18 AM
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Brucester

Posts: 3
Joined: 17 January 2014

I'm trying to work out how much my company can save by having the lights off in the half of the office which is not used.

There are 27 luminaires, each with 4 x 18w tubes making each fitting 72w. This works out at 1944w which if i'm not mistaken is 1.944kwh. Now i've probably not worked this out correctly, but i make that 87.48kwh a week and 349.9kwh a month (4 weeks). Based on .08p per kwh, the lights should be costing £976.92 a month but his total electric bill a month is only £276. So my question is, where have i gone wrong?
 03 February 2014 01:18 PM
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ectophile

Posts: 549
Joined: 17 September 2001

First, I don't know where you got the figure of 87.48kwh a week from. If the lights are on all the time, then 7 x 24 x 1.944 = 326.59kwh. You seem to have made an un-stated assumption that the lights are on for 45 hours a week.

More importantly, 349.9 x 0.08 = 27.99, and not 976.

-------------------------
S P Barker BSc PhD MIET
 04 February 2014 08:23 AM
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Brucester

Posts: 3
Joined: 17 January 2014

Many thanks ectophile. Yep i've got £27.99 now. Maths was never my strong point. I was assuming 45 hours a week too but it's actually more than that so i'm sure he will be pleased to be saving a minimum of £335.88 a year.
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