N. Thornton wrote:
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.
How many fittings to light a house? Those halogen spots are pretty small
area wise in terms of what they do.
I would say that 25W/sq meter is reasonable. I.e. abourt 2 sq meters per
50W spot. Although we are running at far less than that here mainly.
3000 hours is one third of a year. 10,000 hours per year is an 'always
on' figure.
If the lights go on say at 6pm and off at 12pm in any given location,
that's a 25% duty cycle - so 2500 hours per year.
As an intereting aside, I have 6x5 meter rooms one of which is teh
kitcen,. The Aga fully heats that except on the coldest of nights, at a
rated 600W output.
To light it at 25W/square would take 750W. More than enough to heat it
completely. In practice is has a mere 520W and dark areas. It's got
9x50W LV halogens and 3x60W candle bulbs.
In an ideal eco world it would probably have 6x25W sstrip lights :-)
But those would really look ugly...
I look forward to hoghly decorated OLED lighting in due course.
NT
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