Selecting First Tier of Upgrades

By Joe Polastre  |  Posted 2009-11-05 Print this article Print

Selecting first tier of upgrades

The matrix you've built can now be used to select the first tier of upgrades-the ones that are low-capital, minimal-disruption, high-return and often pay for themselves in three months or less. In most non-state-of-the-art operations, the most productive first-tier techniques usually include the following four:

1. Creating hot and cold aisles by rearranging your equipment racks with the cool front panels facing each other in one aisle and the hot vented ends facing each other in the next

2. Raising the temperature of the water in the chillers (typically from 55 to 58 degrees). This must be done incrementally to ensure your equipment can tolerate the change without problems

3. Raising your data center air temperature (typically three to five degrees). Again, this should be done incrementally, a degree at a time

4. Identify and turn off unused equipment

Upgrade, analyze, repeat

Every time you make one of these changes, break out your ammeter and document the savings it produces. The new matrix will also show how the data center's energy consumption patterns and composition have shifted as a result of the upgrades. This information will help you select the next strategy to implement, which will give you the most savings for your investment. The hypothetical measurements used in our test case shows that implementing all these first-tier steps has dropped our data center's PUE from around 4 to 3, resulting in about 33 percent less energy use.

The matrix technique is also a valuable tool for evaluating vendors' claims about the energy savings their product will give you. For example, a virtualization software vendor may claim that their product provides energy savings of 80 percent, but if it only applies to one third of your servers (which consume one third of your power), the actual savings would be nine percent.

Joe Polastre is co-founder and Chief Technology Officer at Sentilla. Joe is responsible for defining and implementing the company's global technology and product strategy. Winner of the 2009 Silicon Valley/San Jose Business Journal 40 Under 40 award and named one of BusinessWeek's Best Young Tech Entrepreneurs, Joe often speaks about energy management and the role of physical computing, where information from the physical world is used to make energy efficiency decisions. Before joining Sentilla, Joe held software development and product manager positions with IBM, Microsoft and Intel. Joe is active in numerous organizations including The Green Grid, US Green Building Council, ACM and IEEE. Joe holds M.S. and Ph.D. degrees in Computer Science from University of California, Berkeley, and a B.S. in Computer Science from Cornell University. He can be reached at

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