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Doug Miller

In article , wrote:

Yes, I think the CFLs make much more sense; particularly since the
"lumismart" device would have to be applied to the entire house. I
wonder what effect would it have on non-light loads?

It obviously would reduce power consumption by 30-40% -- which means, in the
case of resistance heating, for example -- that it also reduces power *output*
by the same 30-40%. Since the amount of energy needed to heat the house, dry
laundry, cook, etc. doesn't change, reducing the power available for the task
means increasing the time required to do it, meaning, for example, that your
furnace will have to run 43-67% longer to keep your home warm. It will take
43-67% longer to make toast, brew coffee, boil water for tea, cook your meals,
or dry your clothes. In short, it won't save a damn thing on anything *but*
lighting -- and probably only on *incandescent* lighting at that.

Another poster cited the figure of lighting being 10% of total electricity
cost - that depends a lot on (a) the type of lighting, and (b) what other
purposes electricity is used for. With a gas boiler, gas oven, gas water
heater, and gas clothes dryer, incandescent lighting represented over 30% of
my total cost for electricity. Switching over to CFLs reduced that to around
10-15%. In a home that had CFLs to begin with, and electric heat, water
heating, cooking, and dryer, I'd imagine the proportion to be a lot less than
that. But let's be generous to the purveyors of this device, and assume that
it's 20% on average. Further assume an average total cost of $125/month.
That's $25/month for lighting. If this device can save 40%, that's $10/month,
making it 200 months = 17 years before you recover the cost of purchasing it.
Add another couple hundred bucks or so for installation by a licensed
electrician, and you're looking at a payback period of pretty near twenty
years. At the lower end of their projection (30%), the period approaches 25
years. And if your lighting costs are only 10% of your total, instead of 20%,
it's nearly 50 years.