[SunRescue] What does it really cost to run that thang!

Thu May 24 10:44:22 CDT 2001

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I wrote this up one day when there was not much going on. I got the info
mostly off of the 'net and partly from the CRC handbook.  It takes
into account the electricity to run the equipment and any A/C needed to
cool it (that is if it is not winter in MN :).  <br>
<br>
This is a small example of some of the considerations of engineering
management. (e.g. if the equipment is cheap/free, it still may not be
cheap/free electricity wise).<br>
<br>
For those of you in Rio Lindo, California, electricity is that thing that
comes on once or twice during the day.<br>
<br>
I am open to comments/suggestions to improve the document, let me know,
thanks!<br>
<br>
Gil<br>
<div align="center">
<font size=5><b>Environmental Cost of Running Equipment<br>
<br>
</b></font></div>
This document is to serve as a tool to help calculate the cost of running
and cooling a piece of equipment.  The formulas used below were
gathered from common knowledge and industry web sites.<br>
<br>
There are two primary power draw concerns, one is the AC used to power
the equipment, the second is the AC used to cool the equipment.<br>
<br>
First, there is the cost of powering a piece of equipment.  This can
be figured out with the following simple formula:<br>
<br>
(Price per KWH/(1000KiloWatts/Watt)) * (Watts/1000)*(unit of time)=cost
to run the equipment<br>
<br>
For example:<br>
<br>
($.08/KiloWatt-Hour) * (100 Watts/(1000watts/KiloWatt)) * (24 hours/day *
30 days/month)=$5.76/month<br>
<br>
 A 100 watt device, at $.08/KWH would cost $5.76/month to run on
electricity.<br>
<br>
To figure out the cost of cooling that device, we need to figure out the
BTU output of that device and the efficiency of the AC unit involved in
the cooling process.<br>
<br>
BTU output of the device:  If the device is generally 100%
electronics (as machine room equipment usually is), the electrical to
heat conversion efficiency of this device is generally near 100% (other
energy output, such as noise and light are negligible).<br>
<br>
The formula to figure out the cost to cool a device, when the wattage of
the device is known, is:<br>
<br>
((Watts *  (3.41 BTUH/Watt) * (unit of time)) / (SEER or EER rating
of unit)) * (Price per KWH/(1000 watts/KW)) = cost of electricity to cool
the equipment<br>
<br>
For example:<br>
<br>
((100 Watts *  (3.41 BTUH/Watt) * (24 hours/day * 30 days/month) / (
10 SEER or EER )) * ($.08 KWH/(1000 watts/KW)) = $1.96/month<br>
<br>
A 100 watt device will cost $1.96/month to cool using a 10 SEER/EER A/C
unit in electricity alone.<br>
<br>
<b>Thus, the total pure electrical cost to run a 100 watt electronic
device off of street power 24/7 is $7.72/month given $.08/KWH and a 10
SEER efficiency A/C unit.<br>
<br>
<br>
</b>At 10:22 AM 5/24/01 -0500, you wrote:<br>
<blockquote type=cite class=cite cite>Dan,<br>
<br>
I'm in Northfield, MN. I run my 630 most all the time, but the 670
is<br>
sporadic. I'd have to leave the 630 off for a month, and see how much
the<br>
bill went down.<br>
<br>
OTOH, when both are running, it makes the basement much more
comfortable,<br>
especially during our fine MN winters.  .  . <grin><br>
<br>
Steve<br>
<br>
-----Original Message-----<br>
From: Dan Debertin
[<a href="mailto:airboss at nodewarrior.org" eudora="autourl">mailto:airboss at nodewarrior.org</a>]<br>
Sent: Thursday, May 24, 2001 10:11 AM<br>
To: rescue at sunhelp.org<br>
Subject: Re: [SunRescue] 690MP cpu is about equivalent to what 
other<br>
sparcs?<br>
<br>
<br>
On Thu, 24 May 2001, Kevin Loch wrote:<br>
<br>
> Why worry about melting?  Circuit boards can take some serious
heat.<br>
> Also, systems like the 670 and 690 have infinately better
airflow<br>
> than an SS20.<br>
<br>
I guess I was undulging in some hyperbole ;). If the module extends
over<br>
the RAM, however, it's possible you could damage memory.<br>
><br>
> What prom version do you need to do HS?<br>
<br>
According to the Mbus reference, 2.14.3, or 2.14.3(h) for the
highest-end<br>
modules.<br>
<br>
Incidentally, if any of you in Excel Energy (Minnesota) territory have
a<br>
6x0MP and can comment on how it's affecting your power bill, I 
would<br>
appreciate it. My rough calculations put it at $8-10/mo, but I haven't
run<br>
it for an entire month yet.<br>
<br>
Dan<br>
-- <br>
Dan Debertin<br>
airboss at nodewarrior.org<br>
<a href="http://www.nodewarrior.org/" eudora="autourl">www.nodewarrior.org</a><br>
<br>
<br>
_______________________________________________<br>
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<a href="http://www.sunhelp.org/mailman/listinfo/rescue" eudora="autourl">http://www.sunhelp.org/mailman/listinfo/rescue</a><br>
_______________________________________________<br>
rescue maillist  -  rescue at sunhelp.org<br>
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</blockquote>
<x-sigsep><p></x-sigsep>
Gil Young<br>
Call Sign: KG4KVX<br>
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