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Glossary 291

many scientists and engineers, representing 500 universities and 80
nationalities.
CHP Combined Heat and Power
Distributed technologies used for data centers.

CIO (Chief Information Officer)
The lead IT executive at a corporation.

cloud computing
The name used for a subset of grid computing that includes utility com-
puting and other approaches to the use of shared computing resources.
Cloud computing is an alternative to having local servers or personal
devices handling users’ applications. Essentially, it is an idea that the
technological capabilities should “hover” over everything and always be
available for users.

cogeneration
The use of a heat engine or a power station to simultaneously generate
both electricity and useful heat. In the United States, Con Edison dis-
tributes 30 billion pounds of 350°F/180°C steam each year through its ptg
seven cogeneration plants to 100,000 buildings in Manhattan—the
biggest steam district in the world.
CPU (central processing unit)
The “brains” of a computer.
CRAC (computer room air conditioner)
A device that controls humidity through humidification or dehumidifi-
cation as required, both of which consume energy.

Cricket
A system for monitoring trends in time-series data, initially developed
to help network managers visualize and understand the traffic on their
networks (http://cricket.sourceforge.net/).
data centers
Facilities that primarily contain electronic equipment used for data pro-
cessing, data storage, and communications networking.

DCiE (Data Center Infrastructure Efficiency)
The DCiE = (IT Equipment Power × 100%) / Total Facility Power. This
is the reciprocal of the Green Grid’s PUE (Power Usage Effectiveness).
The DCiE is considered to be a more intuitive metric than the PUE