This high profile Greenfield IBX data center, with over 170,000 square feet of conditioned data floor area, was commissioned by Critical Systems Testing in 2010. Creating a high level of reliability for mission critical facilities requires not only an in-depth knowledge of the mechanical and electrical systems, but a comprehensive method of testing these systems, under load, in all types of failure scenarios.
The facility features a physical infrastructure consistent with industry leading standards for security, environmental control, power availability, and energy efficiency. This facility utilizes a special mechanical infrastructure with a direct expansion (DX) refrigeration system including five compressors skids with four 100-ton compressors per skid, refrigerant accumulator tank, oil control system and sub-cooler. The rooftop was comprised of 66 air handling units with variable speed control. Each air handler was provided with four refrigeration circuits each served by four of the compressor skids. The uniqueness of the design provided for scavenger cooling loop and two scavenger coils per air handling unit. Each data center aisle was designed with a low velocity/ static pressure duct header. Each aisle arrangement is served by three air handling units dedicated to each duct header.
The sequence of control provided for direct condensing of the saturated refrigerant and sequence of operation that continuously adjusted the saturated condensing temperature based on the exterior wetbulb temperature. Through the control of the refrigerant saturated condensing temperature at the evaporative condensing unit and the scavenger coils at the air handling units the system provided a refrigerant based economization system. The uniqueness of this system required a specialized commissioning approach. Critical Systems Testing, Inc. developed specialized testing procedures which accomplished this goal.
To support the M&V requirements for this facility, CST performed a benchmarking analysis to evaluate power usage and the facility PUE. During the load capacitance verification test a simulation on the reset control of the condenser end of the refrigerant cycle. Prior to the reset verification the facility was loaded 100% on the system compressors. During the reset verification, the scavenger loop and evaporative condensers accommodated an increasing amount of the facility cooling load. The baseline analysis was able to assist in acquiring utility rebates for energy efficiency.