These rooftop air handling units drive cooling system for the Microsoft Dublin data center. These units take outside air and draw it into the data center for use in the air conditioning system. This practice, known as “free cooling” or air-side economization, – allows facility owners to dramatically reduce the amount of energy used in cooling. Chillers, which are used to refrigerate water, are widely used in data center cooling systems but require a large amount of electricity to operate. With the growing focus on power costs, many data centers are using free cooling to reduce their reliance on chillers to improve the energy efficiency of their facilities.
But many locations only allow data center operators to use free cooling for a portion of the year, with chillers used for the remainder. Microsoft says the climate in Dublin, where the average annual temperature ranges between 23 and 80 degrees F (-5 to 27 degrees C) will allow it to use free cooling year-round under normal operating conditions. If the temperature exceeds that range, or external air quality is affected by a nearby fire or contaminants, Direct eXpansion (DX) cooling will be used in lieu of chillers.