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Centralized Control
When designing your cooling plan, it’s best to employ a custom centralized air-handling
system. This sort of system offers several benefits over the prevalent multiple-distributed-
unit system, including the following:

• Better efficiency.
• Can use surplus and redundant capacity.
• Units can work in conjunction with each other, rather than fighting against one
another.
• Uses fluid-cooled chiller plants, which are much more efficient than water- and air-
cooled datacenters.
• Less maintenance is required.

Design for Your Needs
You wouldn’t clomp around in shoes that are two sizes too large or try to squeeze into a
pair of underwear that’s two sizes too small. We expect things to fit right. Unfortunately,
our datacenters’ power needs rarely get the exact fit they need. They are usually loaded
too light.
Although a certain amount of the dark arts are involved in getting the size right, it is
important to get as close as you can with electrical and mechanical systems so that they still
operate properly when underloaded, but are still scalable for larger loads.
You can come close to this Zen-like balance if you consider a few issues:
• Upsize the duct, plenum, and piping infrastructure. This reduces operating costs
and allows a measure of future-proofing.
• Use variable-speed motor drives on chillers, chilled and condenser water pumps. Also,
use cooling tower fans to help with part-load performance. This can be especially
helpful when controlled as part of a coordinated cooling system.
• Examine efficient design techniques, such as medium-temperature cooling loops
and fluid-side economizers.
• Cooling-tower energy use is typically a small portion of energy consumption. If
you upsize cooling towers, you can improve chiller performance and fluid-side
economizers. Although this involves a larger cost up front and a larger physical
footprint, you’ll find savings in operational costs.

Put Everything Together
Efficient cooling isn’t just a matter of installing intelligent equipment. Organization-wide
considerations must be implemented, including design and decision-making issues. Such
issues include:
• Use life cycle cost analysis as part of your decision-making process.
• Involve all key stakeholders to keep the team together on the project. Document and
clarify the reasons for key design decisions.