Have I got my maths right?

nheather

I'm considering replacing the 11 50W GU10s in my kitchen with LED equivalents.  Natural lighting is poor in my kitchen so I don't want to end up with something darker than it already is.

So I've held off for a while but these new Toshibas seem to be close.  I was going to buy one on a trial basis first but I've done some maths and wondering whether it is worth it financially.

I have 11 bubs.
Currently 50W
Replacement would be 8.5W
Saving = 11 x (50-8.5) = 456.5W

Say used 4 hours per day and 47 weeks per year = 1316 hours per year

Total energy saving = 1316 * 456.5 / 1000 = 601 kWh

Unit of electricity = 11p (educated guess)

Total money saving = 601 * .11 = £66

Total cost of bulbs = £330.  Number of years to break even = 5 years

Bit shocked by this - enough to make me stop and think, wait a year or two.

Or have I got my maths wrong somewhere?

Cheers,

Nigel

andy1249

That sounds about right to me , the savings on an individual basis for small appliances are minimal really , the big savings around the house are on heating and cooking , basically more energy efficiency on all the Kilowatt appliances.

johntheexpat

Don't forget to take into account the replacement costs of the original light bulbs, which would (normally) have a much shorter life than the LEDs.  (Plus factor in a cost for your time, disruption etc for changing them, if you want, which may be way more important if the bulbs aren't expensive)

So for every LED (about 50,000 hrs? ) you should get through quite a few normal spots (2000 hrs for an Osram Halopolar ) 50W, 36 degree)

And of course there is the ever rising cost of electricity, which will help reduce the pay-back time.

Costing this kind of project can be a nightmare, if you add in factors for convenience etc.

John

If you were going to wait a year or 2 , it may be worth swapping out for 35w GU10s in the mean time. I doubt you would notice significant difference in brightness with 11 of them , but you would save 30% in running costs