Re: Nah.. They won't be getting a grilling..
"the 20 or so LED light bulbs in my house are costing me about 6 times the cost of electricity they save in replacement - they simply dont last anywhere as long as they claim"
One of the afflictions of being an engineer is knowing what a kWh is, and having the ability to do complicated things like, erm, basic arithmetic…
So let’s see how plausible this all is:
First let’s assume your LED lamps are really crap, not only do they not last the 10’s of thousands of hours promised, yours only last as long as a bog standard filament lamp – say 1000 hours. So you have replaced your 60W with a 6W LED. Your 60W lamp used 1kWh of energy in 1000/60 = 16.67 hours. So in its 1000 hour life, that is 1000/16.67 = 60 kWh of electricity. If you pay 23p per kWh, that’s £13.80. Let’s include the cost of the lamp and round it up to £14.
Your LED will use a tenth of the electricity, so £1.38, and let’s say you paid top money for the poor quality lamp at £5. Brings the total cost to £6.38. So best case, your claim seems to be about 12 x out!
Note also that was an overly pessimistic calculation. In reality you may be paying a bit more for electricity, the LED was probably cheaper than £5, and it will likely do at least 3000 – 5000 hours even if not the full amount promised on the box. That could bring the savings up quite a bit, at 5k hours: old style lamps use £69 quid of lekky, plus a quids worth in lamps, so £70. LED £6.90 of lekky, and a more realistic £3 of lamp – call it £10, and 4 fewer bulb changes.