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To Contain or Not To Contain.....What's The Answer?

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About Gary Dunlap

I have been involved in the telecommunications industry as long as I can remember. One of my best memorys is sitting on a packing crate at age 8, helping my Dad install equipment in a small central office in Okalona, Arkansas. I was strapping blocks (wiring) for a STEP installation.I have worked for several ILECs including Bellsouth

In the mid 80s as the line between IT and Telecom began to blur, I became more involved with IT and networks. During that time I earned several Microsoft and Cisco certifications.

My latest venture is working for Hardy Services and getting something called Site Support Services started.

The Site Support Services Department was created to offer turnkey support for Mission Critical Infrastructure. We instal , reapir and service all types of data center cooling , UPS and power systems, fire suppression systems, acces flooring, data center security access control and video.

Although I am very familiar with Information Technology and the facilities that maintain that infrastructure, the mechanical side is new to me. I am learning as I go with the help of lots of folks here at Hardy and all the online training available to the industry.

I thought I would share my "learning experiences".

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Gary Dunlap's Take On Things

My journey through a new part of a familiar industry.

To Contain or Not To Contain.....What's The Answer?

6 Mar 2010 10:02 AM
  • Comments 2
The use of hot aisle/cold aisle configurations had been around for several years and the physics of it make sense - put the cold air in the front where the equipment breathes and put all the hot air in a separate aisle - but  in this traditional design in a high-density data center, up to 40% of the cool air is wasted. Hot and cold air mix over the top of racks and around the rows. So doesn't this seem like only part of the solution?
 
  The issue here is air mixing, if you mix hot and cold air together, you are expending energy to cool the hot air that you have already cooled and run through your equipment. Basically its a self defeating loop. Containment further separates the hot and cold air , thus making the process exponentially more efficient . But which is the best to contain - hot or cold?
 
  Liebert/Emerson sides with Cold Aisle Containment while APC/Schneider seems to favor Hot Aisle Containment. The reasoning behind this is both sound and self-serving. Since Liebert's customer base is primarily the big traditional "blow the air under the floor" type data center, cold aisle containment makes sense for them. APC's focus is on putting the cooling right on the rack and they have several items in their line that take the heat from the back of the rack and duct it into a hot air plenum.
 
  With either method the idea is to limit air mixing to as close to zero as you can.The critical piece for either method is blanking panels to create a physical separation inside the cabinet at about the mid-point so that the cold air stays on the cold side and the hot air stays on its side.
 
  I participated in a seminar recently on data center efficiency and one of the panelists was from HPs data center support group. I asked him which one was more energy efficient, hot aisle or cold aisle containment. He indicated that the inate energy efficiency for either was similar, however in a hot aisle scenario , the practical considerations in a production environment negated some of the energy savings. For instance , the temperature of the hot aisle containment would typically be over 100 degrees, so that if someone had to work on that side, you would need to open up the containment and maybe even blow some cold air in to make it habitable thus negating some of the benefits.
 
  The fact remains that a aisle containment strategy can make your cooling more efficient and more economical.Dean Nelson, the senior director of global data center strategy at eBay Inc,said in a recent interview with SearchDataCenter.com that one of eBay's data centers had a power usage effectiveness rating of more than 2, which is close to average. After installing containment in his data center, eBay got the number down to 1.78."It was an overall 20% reduction in cooling costs, and it paid for itself well within a year," he said. "It is really the lowest-hanging fruit that anyone with a data center should be looking at."
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