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CPI's New PUE Calculator Reveals Potential Energy-Savings Strategies for Data Centers

February 26, 2009

The CPI PUE Calculator™ is a complimentary tool that gives you the ability to determine your potential data center cost savings when combining CPI Passive Cooling® Solutions with three of today’s most effective cooling strategies including (explained at end of article):

  • KyotoCooling®
  • Waterside Economizer
  • Evaporative Air-side Economizer

CPI Passive Cooling is a simple, yet extremely effective cooling solution that uses the cabinet as a structural barrier to completely isolate your IT equipment's hot exhaust air from the room's cool supply air.

Power usage effectiveness (PUE) is a metric used to determine the energy efficiency of a data center. According to the Uptime Institute, the typical data center has an average PUE of 2.5. This means that for every 2.5 watts in at the utility meter, only one watt is delivered out to the IT load. The Uptime Institute estimates that most facilities could achieve 1.6 PUE using the most efficient equipment and best practices. For more information about PUE visit the Green Grid Website or download this White Paper.

The calculator requires your specific data such as power consumption and cost of electricity, then considers environmental variables (provided by the National Oceanic and Atmospheric Organization) to determine the best possible PUE for your data center. Here is a screenshot of the application:

PUE Calculator Screenshot

Try the PUE Calculator now.

KyotoCooling® – KyotoCooling utilizes outside air temperatures as the cooling source for the data center during hours when the outside dry-bulb temperature is less than the data center supply air temperature requirement. Using a rotary heat wheel (energy recovery system); KyotoCooling removes heat from inside the data center with minimal air transfer between the ambient and computer room temperature. KyotoCooling provides all of the benefits of evaporative air-side economizers without the exposures like contamination and humidity control. CPI Passive Cooling Solutions maintain the critical hot and cold air separation required for maximum KyotoCooling effectiveness.

Water-side Economizer – A water-side economizer uses the building’s cooling towers to cool the data center chilled water loop by taking advantage of the hours of the year when the outdoor dry-bulb temperature is sufficiently lower than the chilled water supply set point. Instead of running the chiller plant during those hours, the cooling tower water is bypassed around the chiller plant and diverted to a heat exchanger so that it can cool the chilled water directly. CPI Passive Cooling Solutions increase economizer hours by providing complete isolation between supply and return air in the data center, allowing for higher supply air temperatures and associated higher chilled water temperatures.

Evaporative Air-side Economizer – Instead of cooling and re-circulating the hot air from the servers, evaporative air-side economizers expel the hot air outdoors and draw in outside air to cool the IT equipment when the outdoor wet-bulb temperature is below the data center supply air temperature and employs adiabatic pre-cooling during those hours when the ambient temperature exceeds the data center requirements. This portion of the evaporative air-side economizer control scheme is called free cooling. Evaporative air-side economizers can reduce HVAC energy costs in cold and temperate climates and warm and dry while also potentially improving indoor air quality, but are most often not appropriate in hot and humid climates. CPI Passive Cooling Solutions maintain the hot and cold air separation required for maximum evaporative air-side economizer effectiveness.

>>What is your opinion concerning PUE? Do you think it is an accurate method of measurement? Leave your comments by selecting the “Comments” link below. If you have questions about the CPI PUE Calculator, please call us at 800-834-4969. Kim Ream, Sr. eCommerce Specialist


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