NDA 4 is a 20 MW co-location data center in Santa Clara California that was built in
2011. The primary cooling source is 30 Trane Intellipaks AC units with airside
economizers and direct evaporative cooling/humidification. From Day 1 the data
center suffered from poor temperature/humidity controls, poor energy efficiency,
and poor reliability. A number of incidents resulted in partial or complete loss of
cooling. Taylor Engineers determined that most of the problems related to a bad
BAS design, that relied too heavily on centralized control, and bad sequences of
operation that relied too heavily on unreliable sensors and failed to take full
advantage of the airside economizers and direct evaporative cooling.
We designed a new controls system that featured distributed local controllers and
re-wrote all the control sequences. The controls upgrade was awarded to an ALC
controls contractor. In order to seamlessly transition the live data center to a new
control system, we worked with the contractor to mockup a simulator to fully test
the new controls architecture and new sequences before installation. We then
carefully phased the transition and incrementally functionally tested all sequences
on the live data center. The upgrade reduced the PUE (Power Usage Effectiveness)
from 1.44 to 1.22, resulting in energy savings of 10 million kWh per year.
Temperature and humidity control has improved, and most importantly, uptime is
now 100%.