How do I calculate cooling cost per server?
Solution 1:
- You need to convert BTU to watts.
- Convert Watts to kilowatts
- Then multiply the kilowatts by whatever you currently pay the electric company per kWh.
- $$$ Profit $$$
You should have two sets of numbers: the electricity used by the systems (880W in your case) and the electricity used to cool them (convert Tons to BTU to Watts to kWh), then add them up.
You not only have to account for the electricity you use to power the systems, but also the electricity used to cool them.
You computed the cooling you need not necessarily the cooling you provided. These can be two separate numbers. If your ambient temperature was around 70F these numbers are close enough.
Solution 2:
Here's the easy way. You can do a lot of fancy math, but in the end analysis, the amount of electricity it takes to cool the equipment is equal to the amount of needed to power it. There is solid scientific rational behind this in the bowels of APC's web site, if you're curious.
So, your 880W load with cooling would be 1760W total. From here it's clear sailing. Let's say your kilowatt-hour (kwh) rate from the utility company is $0.17/kwh.
Your annual kwh load will be 1760 watts * 24hrs/day * 365 days/hr / 1000 watts/kw = 15,418 kwh hours per year.
15,418 kwh * $0.17/kwh = $2,621/yr