[SunRescue] cost of power, A/C, Information and peer review

[Gil Young]

I had the urge to figure out what it truly costs to run a piece of 
equipment, so I thought i'd share it with you all so you can get an idea of 
power and AC costs to run some of those old beasts you are 
harboring.  Also, wanted to throw it out for peer review, accuracy, 
suggestions, etc...  I'm all ears to make it a better or more accurate 
analysis.

Please, no applause, just send me your old SS1000's if you cant afford to 
run them anymore :).

Gil

---------------- Begin Document -------------

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.

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.

First, there is the cost of powering a piece of equipment.  This can be 
figured out with the following simple formula:

(Price per KWH/(1000KiloWatts/Watt)) * (Watts/1000)*(unit of time)=cost to 
run the equipment

For example:

($.08/KiloWatt-Hour) * (100 Watts/(1000watts/KiloWatt)) * (24 hours/day * 
30 days/month)=$5.76/month

  A 100 watt device, at $.08/KWH would cost $5.76/month to run on electricity.

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.

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).

The formula to figure out the BTUH output of a device, when the wattage of 
the device is known, is:

((Watts *  (3.41 BTUH/Watt) * (unit of time)) / (SEER/EER rating of unit)) 
* (Price per KWH/(1000 watts/KW)) = cost of electricity to cool the equipment

For example:

((100 Watts *  (3.41 BTUH/Watt) * (24 hours/day * 30 days/month) / ( 10 
SEER/EER )) * ($.08 KWH/(1000 watts/KW)) = $1.96/month

A 100 watt device will cost $1.96/month to cool using a 10 SEER/EER A/C 
unit in electricity alone.

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.

---------------- End Document -------------

Gil Young
Call Sign: KG4KVX
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