NDA_3 Data Center

Santa Clara, California

NDA 3 is a 4.5 MW colocation data center built in 2009 served by a (4)
chiller water cooled CHW plant and (22) chilled water air handlers with
airside economizers. Taylor Engineers was original retained to investigate
the root causes of a series of chiller failure events during the summer of
2017 on near design days. After identifying the mechanical and controls
design flaws that led to the failures and providing recommendations to
prevent recurrence, we were again engaged to (1) design a new control
system and sequences of operation for the data center and (2) design a
capacity expansion utilizing computer room air handlers (CRAHs).
The new ALC control system utilizes an all ethernet topology to maximize
network speed and a distributed failsafe control scheme to silo the impacts
of any control device failure, thereby maintaining "N" devices under
automated control in any single device failure scenario. To safely transition
to the new controls while the data center remained in operation, we
worked with the controls contractor to functionally test the sequences of
operation on a simulator test bench. After thoroughly validating all
sequences, the controls retrofit cutover happened one data hall at a time,
followed at the end by the chilled water plant cutover. Field functional
testing was phased to minimize risk, with testing of the first data hall
occurring prior to cutover of the second. Since commissioning completion in
October 2018, annualized data center PUE has dropped from 1.48 to 1.28,
saving our client 5.4 million kWh per year.

Size (ft²)




Project Type

Data Center

Scope of Work

Failure Forensic Analysis, Mechanical Retrofit Design, Full Controls Retrofit Design and Commissioning










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Disclosed upon request

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