Bob Johnson wrote:
- reduced energy use for everyone.
I think the difference in energy use would be so small as to be
pointless. If I have a system that consumes 75 kilowatt hours per
month, and I spend an extra 0.05 kilowatt hour per month updating
ports, is the difference (less than 1/10 of 1 percent) really
meaningful? I can't even measure my power usage accurately enough to
detect the difference. Convince me to use three liters less hot water
per month, and you will save more energy.
How do you get the figures above? I
measured electricity use for a typical 2 year old computer (excluding
screen) as:
- computer idling - 80 watts
- computer working hard - 125 watts
That's a diff of 45 watts. Suppose normally you use your computer 4
hours a day and it normally takes you 20 hours to upgrade your ports.
You start the upgrade while using the computer but you leave it
compiling for an extra 16 hours. Thats 4 hours at 45 watts plus 16 hours
at 125 watts.
Thats 2180 watt hours or over 2 kWh on top of your normal use for one
port upgrade.
However you jig the figures there is no escaping that cpu cycles use
energy. Multiply by the number of times ports are upgraded per computer
per year and the number of computers being upgraded and a package system
seems like a worthwhile saving. (Thanks Colin Percival et al for
freebsd-update, this aspect of it hadn't occurred to me)
To complete your comparison if you used electricity to heat 3 litres of
water from 15 degC to 55
degC you would use 0.139kWh.
Chris
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