94 degrees is the target hot aisle temp, we reset supplies higher when when the hot aisles on either side of the cold room are unoccupied which actually is the majority of the time since this is a building that does not have many occupants even during normal working hours. Keep in mind 2/3 of a normal week is outside of business hours. When outside ambients are colder we can lower the supply and corresponding hot aisle as desired at no cost.

We actually do measure wet bulbs for selecting mode of operating our economizer systems.

There are two primary air handlers per cold room that sit directly above the cold room in a mezzanine (the second floor with damper/lover system). Each unit is 46,000 cfm and rated at approximately 100 tons of refrigeration. They are commercial/catalogue indoor rated units with a mixed air chamber and cooling coil. The outside air intake is from the roof.

Are you looking at enthalpy when in economizer mode, the picture shows that the building is next to a pond of some size? One would assume that the other side of the building is the chiller yard. The picture looks like you have Trane equipment on the roof is that what you are using for the fresh air intake.

The 74 degree inlet air temp that’s nice, but the 94 degrees in the hot row, that sucks to work in. The nice thing with the higher temps that the Data Centers are going to; the CRAH/ CRAK units are no longer are removing latent heat from the air. This allows for better efficacies numbers.

Following are key features that will contribute to the RTP data center’s outstanding energy efficiency:

* 74° F average supply air temperature: Using a higher temperature threshold on supply air (74° F instead of 55° to 60° F) allows NetApp to dramatically reduce cooling costs.

* Airside economizer: The data center is cooled by using just outside air (free cooling) 67% of the time during the year.

* Pressure-controlled room: Modulating fans, based on NetApp’s proprietary technology, supply pressure-controlled rooms and regulate the volume of air to avoid oversupplying air and wasting energy.

* Cold aisle containment: The cold room separates the cold and hot air streams to protect supply air temperatures from being affected by hot air returning from the racks.

* Overhead air distribution: Instead of pumping cold air up through the floors (raised floors), overhead air distribution takes advantage of cold/hot air buoyancy and eliminates ductwork, reducing the energy needed for fans.