Data Centers consume about
over 70 billion kWh of electricity yearly, 2% percent of the total, with
increasing numbers of users as more information is shared and stored online. Energy
efficiency potential exists with small data centers, defined as under 5,000
square feet of computer floor space; these centers house over 50 percent of all
servers and consume about 40 billion kWh per year.
small
data centers lack the resources to implement energy-saving opportunities
Energy Efficiency measures
achieve savings of 20 to 40 percent without impacting IT equipment reliability,
when properly implemented.
Unused Servers an estimated
20-30 percent of servers in data centers are consuming power, cooling, and
space while not working; idle servers consume half the power as at full load.
To better manage server usage and utilization, create and update a server
hardware and application inventory that tracks the number of applications
running on each server.
mapping
applications to the physical servers helps identify unused servers
Power Management saves
energy by turning off power or switching equipment to low-power modes when not
in use. Energy Star servers are shipped with three categories of power
management enabled. Utilize built-in or add-in cards that enable servers to be
powered on or off remotely. Improve air management; the key task is to ensure
that cool air from the data center’s cooling equipment gets to the air inlet of
the IT gear, without getting mixed with the hot air exhausted from the back; also
ensure that hot air going back to the cooling equipment does not mix with the
cold air. This is achieved by clearing clutter from the desired airflow path,
blocking off bypass and recirculation airflow paths within and between the
racks and the raised floor.
Energy Savings can be
realized through two measures: raising temperature setpoints and reducing
air-flow rates. There is a broad range of air-management strategies that span
the range of complexity and cost; containment of cold or hot aisles is a very
effective approach as is increasing temperature setpoints to deliver air
towards the high end of the ASHRAE recommended range; temperature guidelines
allow much broader operating ranges than those commonly used, allowing the air
temperature at the IT equipment inlet to be raised-up to 80°F or higher- which
considerably reduces cooling energy usage compared to the inlet temperatures of
65-70°F commonly used.
Computer-Room Air
Conditioners (CRACs) and Computer-Room Air Handlers (CRAHs) control their
temperatures based on return air; these CRAC/H setpoints will be much higher
than the IT inlet temperature. In chilled-water systems, if raising the air
temperature also enables raising the chilled water temperature, a 1°F rise in
the chilled water temperature typically results in a 2 percent reduction in
chiller energy.
Active Humidity Control
energy savings can result from reducing humidification and the over-cooling and
reheat typically involved in active dehumidification. ASHRAE humidity
guidelines, expanded on the low end to about 8 percent relative humidity, allow
much broader operating ranges than those commonly used. As a result, large
energy and water savings are possible by eliminating this control.
Uninterruptible Power Supply
UPS requirements. Risk-averse IT managers often overdesign redundancy into
their systems, when in fact many IT applications can be shut down if there is a
power disturbance and restarted without adverse effects. Verifying power backup
requirements can help eliminate capital costs for unnecessary or oversized
redundant power supplies or UPS equipment.
high
reliability items should move to larger data centers or cloud solutions
Establish server refresh
policies that account for increases in generation-on-generation computational
ability, energy -efficiency, and power management improvements. When purchasing
new equipment, servers with solid-state drives SSD, rather than hard disk
drives, could be considered, as they feature faster speeds, are generally more
reliable, and consume less power. New equipment typically has much more
computing power than older equipment, which facilitates consolidation and
virtualization. Consolidate and Virtualize
Applications typical servers in server rooms and closets run at very low
utilization levels - 5-15%, while drawing roughly 75 percent of their peak
power on average. Consolidating multiple applications on a smaller number of
servers accomplishes the same amount of computational work, and the same level
of performance, with much lower energy consumption. Virtualization consolidates
applications, allowing multiple applications to run in their own environments
on shared servers. Increasing server utilization reduces both the number of
servers required to run a given number of applications and overall server
energy use.
Distributed Server Rooms are
typically not very energy efficient. If a central data center is available, you
may be able to save energy and reduce your utility bill by moving your servers,
or their applications, to that location. Many organizations are moving their
equipment to co-location or their applications to cloud facilities
co-location
and the cloud provide better efficiencies than on-premise server rooms
Power Monitoring identifies
the energy use and efficiencies of the various components in the electrical
distribution and cooling systems. While power monitoring by itself will not
save energy, it can help identify energy saving opportunities. Power meters can
be installed at the panels serving the cooling units, or directly on IT and
HVAC equipment. Often power distribution products will have built-in monitoring
capability.
Air-side Economizers draw in
outside air for cooling when conditions are suitable. Server rooms with exterior walls or roof are
a pre-requisite for air-side economizers. This could be in the form of an
exhaust fan removing heat in one portion of the room and an opening in another
location allowing cool, outside air to enter; alternatively, it could be in the
form of a fan coil or CRAC/H with air-side economizer capability. Depending on
the climate zone in which the server closet is located, this strategy can save
a significant amount of energy by reducing compressor use needed for cooling.
Training is important to
keep up with the rapid evolution of technologies and solutions in the data
center sector; skills are required
to perform accurate data center energy assessments. The Data Center Energy
Practitioner DCEP training program certifies energy practitioners qualified to
evaluate the energy status and efficiency opportunities in data centers. The program reinforces best practices
and introduces new tools and techniques in IT equipment, air management,
cooling systems, and electrical systems.
Saving Energy in Your Data Center
