Retrofitting a data center is about managing limitations
and trade-offs. Decision-makers have to consider physical
limits (such as the weight a floor will support and how much
cooling equipment can fit into an existing space). Then
there’s infrastructure to think about: It would be
difficult to swap out an old uninterruptible power supply (UPS)
cable for a brand-new one. Such restrictions have an impact on
energy efficiency too: Existing UPS cables generally operate at
85 percent efficiency, whereas the newest ones are in the range
of 97.5 percent. To reach the highest efficiency numbers,
you’d need to change your entire data center
architecture, which is impractical for most companies.
Retrofitting a data center to make it more energy efficient
has its restrictions, but doing so can be less costly than
having to rebuild an entire facility. To weigh the
variables—and achieve energy cost savings – you
need to know what’s broken. Here are five tips for
determining the efficiency of your data center and how to make
it green as can be.
1. Get to know your data center.
An energy efficiency assessment from someone who specializes in
data centers should be a priority, says Neil Rasmussen, CTO of
American Power Conversion (APC), a provider of data center
power and cooling equipment. IBM, EYP Mission Critical, Syska Hennessy, APC and Hewlett-Packard offer such services.
HP recently added Thermal Zone Mapping to its assessment
offering. This service uses heat sensors and mapping analysis
software to pinpoint problem areas in the data center and helps
you adjust things as needed, says Brian Brouillette, vice
president of HP Mission Critical Network and Education
Services. For example, the analysis looks at the organization
of equipment racks, how densely the equipment is populated, and
the flow of hot and cold air through different areas of the
space. It’s important to place air-conditioning vents
properly so that cool airflow keeps equipment running properly,
without wasting energy, says Brouillette.
2. Manage the AC: Not too cold, not too hot, but
Energy efficiency often starts with the cooling system.
“Air conditioners are the most power hungry things in the
data center, apart from the IT equipment itself,” says
Rasmussen. If your data center is running at 30 percent
efficiency, that means for every watt going into the servers,
two are being wasted on the power and cooling systems, he says.
To reduce wasted energy, one of the simplest and most important
things you can do is turn on the AC economizers, which act as
temperature sensors in the data center. According to Rasmussen,
80 percent of economizers are not used, just as IT
administrators often turn off the power management features in
PCs. It’s also important to monitor the effects of
multiple air-conditioning systems attached to a data center;
sometimes, Rasmussen says, two AC systems can be “out of
calibration” one sensing humidity is too high and the
other sensing it’stoo low; their competition, like a game of
cooling tennis, can waste energy.
Richard Siedzick, director of computer and
telecommunications services at Bryant University, uses such
features in his data center. “If the temperature rises to
a certain level, the AC in that rack will ramp up, and when it
decreases, it will ramp down.” The result is a data
center climate that few are used to. Instead of being met with
an arctic blast at the door, Siedzick says people have told him
his data center is too warm. That’s not actually the
case: AC economizers help cooling stay where it is needed,
rather than where it is not. And that means increased
efficiency and monetary savings. “We estimate we’ve seen
a 30 percent reduction in energy [in part, due to more
efficient cooling] and that translates into $20,000.”
Siedzick says other precision controls, such as humidity
sensors, are used in the data center as well.
3. Place equipment in the right spot.
Most data center floors are raised and tiled. Tiles should be
located near the air inlets of IT equipment, not near the
exhaust. Since the exhaust areas (where the air is coming out)
run hotter than the inlets, making sure tiles (which provide
ventilation) are located in the right place makes the AC units
run more efficiently. Also, make sure you have the right number
of vented tiles in your data center. If you have too many or
too few, efficiency goes down.
4. Mind the gaps. Eliminate nooks and
Many racks in data centers contain gaps, either as a result of
extra space or equipment that has been removed. Whatever the
reason, it makes airflow unnatural, and that’s bad for
efficiency. “The exhaust air can go back through the
intakes of the equipment, which makes you have to run the AC
colder,” says Rasmussen. The answer: blanking panels.
Installing these panels onto server rack cabinets are a way to
make the air flow in a data center more efficient.
Many people forget to install blanking panels, even though
server manuals from OEMs mandate their use. But Rasmussen says
they are inexpensive (sold 100 to the box, in some cases) and
easy to install.
5. Can it get hotter in here? Check.
Once you’ve done everything listed above, check to see if
you can run the air-conditioning at a higher temperature.
Rasmussen says that most units are set at around 55 degrees and
some get as low as 45 degrees. The lower the temperature, the
less efficient your data center is. “You should run that
AC hot as you can without the servers overheating,”
Rasmussen says. He says 68 degrees is a good target, but unless
you are operating a brand-new data center with a top-notch
design, you are unlikely to hit such a number.
If you follow the rules above, Rasmussen says it’s
likely you can increase the temperature to 55 or 60 in a