Fwom:The Natural Philosopher )

Additional gas bill per 2000 hours to replace lost heat? probably
about £5

So £9.23 per 2000 hours in reality.


Good point.

2000 hours of 100-23w = 2000x77w = 154kWh
gas @1.5p/kWh = £2.31

Heating in use lets say 2/3 the year, so the saved money in that is
2/3 x 2.31 = £1.54

Thus real saving figure now:

£13:23 to £9:03 per light fitting per 2000 hours.

Last questions are how many such fittings does it take to light a
house, and how long does it take to use the lights for 2000 hours.


NT