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Cooling Plant Optimization Offers Data Center Benefit
October 27, 2011 - Contact FacilitiesNet Editorial Staff »
This is Casey Laughman, managing editor of Building Operating Management. Today's tip is that cooling plant optimization can offer energy-saving benefits in data centers.
Cooling plant optimization includes several key elements that, when combined, can produce significant savings in energy use over the life of the facility.
The first element is supply temperature control. Eliminating humidity control from the air conditioning units (ACUs) on the data center floor allows for the humidifiers and reheat coils to be removed from the ACUs. The result is a lower first cost and lower maintenance and operating cost for the system.
Because some outside air is required to ventilate the raised floor environment, an effective solution is a central ventilation and humidity control system that utilizes an ACU using 50 percent outside air and 50 percent return air to humidify and dehumidify the data center. The amount of moisture needing to be added or removed from the space is not a function of the total air circulated in the data center, but purely a factor of the condition of the outside air used for ventilation and the moisture migration through the building skin.
An efficient option is ultrasonic humidification, which uses high frequency sound waves to evaporate water and operates on one-tenth the energy of a conventional electric system that boils water. Ultrasonic systems use de-ionized water, which some view as a complication not worth the hassle. However, modern packaged de-ionized water systems are highly reliable and provide a boon in maintenance savings.
Elevating the chilled water temperatures is another element that will help optimize a data center's cooling plant. Because the data center can be cooled effectively with 60-degree supply air, it is possible to supply 50-degree water. This increases the efficiency of the chillers, and significantly extends the annual hour of free cooling with a water-side economizer cycle.