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desired temperatures in that aisle. If
demand on the data center is low
and a particular aisle is not
generating much heat, thermal
sensors and controls will perform
accordingly.
TURN UP THE TEMPERATURE
In your data center: Aisle containment
also enables you to manage cooling
to address server inlet temperatures,
rather than indirectly based on return
air temperatures. This increased
precision can provide the confidence
to raise data center temperatures
closer to the ASHRAE maximum of
80.5° F.
In your chiller: In thermal
management systems that use water
to capture and remove heat, raising
water temperatures in the chiller can
deliver additional savings. Chillers
have traditionally been set to keep
water temperature at 45° F, but many
facilities are now raising chilled water
temperatures above 55° F to reduce
chiller costs and widen the window at
which economizers can operate.
MATCH COOLING TO THE
LOAD
Variable capacity thermal
management units equipped with
variable speed digital compressors
and variable speed or EC fans are
becoming the norm. These
technologies allow thermal
management units to match their
capacity to changes in the IT load
and operate more efficiently at all
capacities. This is key to improving
unit efficiency, since the thermal
management system is sized for a
maximum IT load that rarely occurs.
Any system that can’t efficiently adapt
to actual operating conditions is
wasting energy.
Fans are big consumers of energy in
thermal management units.
Upgrading from fixed speed to
variable speed fans can yield a
particularly strong return on
investment because of the
relationship between fan speed and
energy consumption: reducing fan
speed by 20 percent provides almost
80 percent savings in fan power
consumption. That means a relatively
small adjustment in fan speed can cut
fan energy consumption in half.
UPGRADE THERMAL
MANAGEMENT SYSTEM
CONTROLS
Intelligence can make or break a
thermal management approach, and
intelligence requires sophisticated
controls. Sophisticated does not
necessarily mean expensive. An
amazing amount of functionality is
built into the current generation of
many thermal management system
controls, including multi-unit
teamwork control with fan
coordination, coordination between
external condensers and indoor
cooling units, capacity and power
usage monitoring, auto-tuning,
economizer control, and custom
staging and sequencing. New
controls provide the ability to safely
implement and coordinate each of
the strategies mentioned above.
EXTEND VISIBILITY BY USING
WIRELESS SENSORS
The more visibility the controls have
into equipment operating parameters
and conditions in the data center, the
better decisions they can make. New
generations of wireless sensors are
making it simpler and more
affordable to extend visibility beyond
return air and supply air temperatures
to include server inlet temperature.
When variables such as server inlet
temperature, supply air temperature,
return air temperature, water
temperature, outside temperature,
fan speed and unit energy
consumption are all monitored in real-
time, the control system has the data
it needs to optimize performance
within a single unit, across multiple
indoor units, and between indoor and
outdoor units.
DEPLOY NEW ECONOMIZER
TECHNOLOGY
The introduction of variable capacity
cooling marked a major step forward
for data center thermal management,
but the promise of matching thermal
management equipment performance
to real-time conditions is just now
being realized by using economizers
integrated with intelligent controls in
thermal management systems.
Traditional economizer systems use
outside air or complex water systems
to minimize the use of compressors or
chillers. They have a long history in
the data center and even in
temperate climates can deliver
significant savings. For example, in
Atlanta, Georgia, economization can
provide cooling energy savings of
more than 40 percent. The challenges
of economizer use have always been
to use outside air or water in ways
that do not impact the reliability of IT
systems and to be able to easily
control the level of economization
based on changing outside
temperatures.
Economizers with pumped refrigerant
have now been integrated directly
into thermal management systems
that include a high-efficiency variable
capacity compressor. System controls
measure IT loads and outdoor
temperatures and automatically
switch in and out of economization
mode. During optimal ambient
Compressors are the biggest energy consumer in
thermal management systems. During optimal
ambient conditions, a system equipped with a
pumped refrigerant economizer can provide
full economizer operation to reduce compressor
energy consumption to zero.