Thursday, February 21, 2008

Focus on the Data Center

Energy use has increased 4 to 5 times in the last decade at data centers.

Inefficiency - Data center electricity use is growing more than twice as fast (3.2% annually) as total electricity use. Total data center energy consumed is an estimated 1.2% of total US electricity consumption:

  • 54 billion KWH annually or equivalent of 5.4 million homes.
  • 38 Million tons of green house gas or equivalent exhaust from 18 million cars
In addition to the energy used to power the server, the heat generated by the server requires energy to cool. For each watt used to power a server, an extra watt is used to power the fans that cool that server. Plus the cost of air conditioning or other cooling techniques consumes even more energy.

Under-utilization of servers is rampant with only 10 – 20 % utilization on average. A server utilized only 20% is wasting half its power when using standard power supply technology. Less energy is wasted at higher loads. According to Ecos Consulting, most power supplies are only 60-70% efficient across all loads.

Opportunity - For each server decommissioned:

  • Avoid 7 tons of C02 pollution each year
  • Save approximately 10,000 KWh annually or equivalent of the average home’s annual electrical consumption.
  • Reduce costs by $1,100 annually.
  • Fewer servers reduce other related costs such as network infrastructure, storage infrastructure, and administrative overhead.
  • Cost avoidance - Many existing data centers are maxed out on power and space available and will require major infrastructure upgrades to support.

Improved power supply efficiency of 80+% efficiency at various loads results in $90 savings annually on a 600W power supply unit. Google is running its power supply units at 90% efficiency as reported by Urs Hölzle, Vice-president of Operations.


  1. Use the power management feature. Test first since some vendors are less sophisticated in their power management integration, which may cause issues.

  2. Eliminate the estimated 10 – 15% of the orphaned applications and servers that are unused.

  3. Turn-off equipment used only during peak periods. Intuit for example, turns off many of its servers after April 15.

  4. Adjust cooling to run data center warmer. A degree less cooling on average saves 3 to 4% of A/C costs.

  5. Upgrade Data Center lighting to energy efficient compact and linear fluorescent. Turn-off lighting in server only areas and provide task lighting for engineers for installation and maintenance.

  6. Consolidate applications and servers. Consolidation of production applications is not trivial, so start more simply. With a little effort, some of the development and test environments that are used during a project can be reused by the next project. When consolidating production, ensure that applications share similar service levels and BCP requirements and experience complimentary peak usage.

  7. Improve power to server utilization by upgrading power supply technology. Advanced power supply technology achieves 80+% efficiency even at low utilization.
  8. Buy energy efficient equipment and educate suppliers that efficiency is a critical feature. Encourage innovation, such as cool circuits, variable fans. water cooling, and circuit heat tolerance. Insist that industry define a consistent energy efficiency measurement standard to provide buyers with a simple method to compare products. Current energy efficiency standards are confusing which each vendor touting a measurement and benchmark that makes them a winner in the energy efficiency race.
  9. Replace power hungry equipment with more efficient energy utilization. With reduced cost of vendor h/w maintenance, lower utility costs, potential rebates offered by your utility company and enhanced functionality, can make replacement a solid ROI.

  10. Purchase electricity from renewable resources.



  • Comprehensive list of 67 Data Center energy efficiency best practices provided byLawrence Berkeley National Laboratory.
  • Run the data center at higher temps. ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers) updated its guidelines for data centers and broadened the allowable temperature and humidity ranges, which can result in significant energy savings in its publication "Thermal Guidelines for Data-Processing Environments".
  • Give feedback to the US Government EPA Energy Star standards and an NGO that certifies power supplies and industry standards committee (SPEC) that are defining energy efficiency rating methods.
  • List of manufacturers receiving 80-plus certification where power supply is 80+ % efficient under low to high loads.

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