Re: [tlug] Power Consumption Cost

[Jim <jep200404@example.com>]

In really really rough terms, at 10 yen per kWh, 
figure 100 yen per year for each Watt that your computer sucks.
At 25 yen per kWh, figure 250 yen per year per Watt. 

Erin quoted, but did not answer a question that I asked: 

> What is the price of power per kWh? 

On Thu, 22 Jun 2006 11:13:11 +0900 "GMO Unix Erin D. Hughes" <erin-hughes@example.com> wrote:

> On Wed, 2006-06-21 at 10:06 -0400, Jim wrote:
> > Erin D. Hughes wrote: 
> > 
> > > 4500 [yen] in additional power consumption a year. 
> > 
> > How many watts does your computer use? 
> > What is the price of power per kWh? 

> I am [using] a 300 watt PS but I am not quite sure what the kWh rate is
> here. 

OK. It's clear you don't know how much power your computer uses. 

Let's play with your number anyway. 300 Watts for a year would 
be about 2628 kWh (kiloWatthours). At 10 yen per kWh, that would 
be about 26280 yen per year. At 25 yen per kWh, that would be 
about 65700 yen per year. 

Back to reality. A 300 Watt power supply can crank out a 
_maximum_ of 300 Watts (and would consume a bit more than that). 
Your computer likely uses much less power than the maximum. 

Let's use a wild arse figure of 100 Watts consumption for 
a five year old computer with one hard drive. 
At 10 yen per kWh, that would be about 8760 yen per year. 
At 25 yen per kWh, that would be about 21900 yen per year. 

All of these figures are significantly higher than the 
4500 yen per year that you cite. 

Almost all the power consumed by the computer becomes heat. 
In winter, this reduces how much your heater needs to run. 
If you have electric resistance heat, as long as your 
space does not rise about the desired temperature, running 
computers will not affect your bills. In summer, you pay 
twice (or more) for the juice your computer uses. You pay 
once for the power consumed by the computer and again to 
pump the heat from it out of your space if you use air 
conditioning. 

In any case, for a computer to use only 4500 yen per year 
of electrical power, at 10 yen per kWh it would have to 
use only about 51 Watts of power, or at 25 yen per kWh 
it would have to use only about 20.5 Watts of power. 

I have a stripped old '486 computer that I use for a 
firewall. It has the motherboard, with 66MHz CPU and 16MB 
of RAM, two NICs (with 10Base-2 interfaces that gobble 
more power) and a floppy drive. It has no hard drives 
or CD-ROM drives. The only fan is in the power supply. 
The computer uses between 19 to 22 VA (measured!). 
Actual power consumption would be less than that, 
(divided by the power factor). 

It is possible to have a computer that would use only 
4500 yen per year of electricity. Without further 
information about your computer, it's unlikely that your 
computer is such a computer.