Analysis: Should You Be Air Conditioning Computer Rooms?

Many organizations and sometimes even people will use air conditioners to keep computers cool, to prevent them from breaking down. The breakdown of computers incurs a replacement cost, but air conditioners come with their own costs as well, such as maintenance, and especially electricity costs. This article is focused on the electricity cost.

Computer Room – Obtained with thanks from xaxa29 on Flickr – http://www.flickr.com/photos/charlie29/

Fictional Case Study:

If a 20,000 BTU air conditioner (based on what I have seen in computer rooms I have worked in) is used to cool a computer room for 12 hours per day (not an inverter unit), it would consume 24 kWh per day, since 20,000 BTU units typically draw 2,000 watts of power, assuming an EER of 10, which is average, based on what I have seen, and also the U.S Department of Energy says that is the average. Air conditioner EER ranges from 8 to 11 (not to be confused with SEER).

24 kWh per day adds up to 720 kWh, after a month, or 8,640 kWh per year. This would cost $72 USD, assuming an electricity rate of 10 U.S cents per kWh, which adds up to $72 USD per month, or $864 per year.

$864 USD already exceeds the cost of a new computer. After two years, the cost adds up to $1,728 USD, which far exceeds the cost of typical new computers.

So computer room cooling for the sake of lowering the cost of computer repairs saves no money, but will actually cost more. This conclusion is based on the fact that computers (which are not in sealed rooms, but adequately ventilated ones) can last a few years without air conditioning.

I would not turn off the air conditioning in a tiny sealed server room because it is intentionally small and sealed to prevent ventilation to keep cold air in, to lower air conditioner power consumption. This means that computers would have to be transferred to an adequately ventilated room to avoid A/C usage.

If this cooling technique was used for a server room which operates 24 hours per day, then the 20,000 BTU unit would use twice as much electricity and cost $144 USD per month, or $1,728 USD per year. Assuming that computers last an average of 5 years, $8,640 could be saved on air conditioning by avoiding it for that 5 year period.

Some server machines are very expensive. This is sometimes due to the fact that they are very powerful. More powerful computers generate more heat, and hence require larger air conditioners which require more energy.

Just because a computer is more expensive, does not necessarily mean that is is more worth it to refrigerate it. The ratio of return on investment to air conditioner cost could very well be the same as that of muc cheaper setups.

I didn’t even factor in the fact that the cost to repair computers is usually limited to the cost of the motherboard and/or processor + labour charges, which is only a fraction of the cost of a new computer. The hard disk drive, optical DVD, CD, and other drives, RAM, power supply unit, case, network cards, sound cards, etc can last long, and most of them will still be working, so whole computers do not usually have to be replaced, unless they are old and obsolete.

Jamaican Revision:

Exchange rate at this time: $1 USD = $88 JMD.

Assuming an electricity cost of $0.43 USD per kWh, or $37 JMD per kWh, and the same variables as above, the air conditioner would cost $3,715 USD ($326,920 JMD) per year if operated 24 hours per day, or $1,857 ($163,468 JMD) per year if operated for 12 hours per day.

Exceptions

There may be exceptions to this rule. Some computer systems have to be as reliable as possible because a brief breakdown could cost an organization a tremendous amount of money.