air-cooled chiller system: A cooling system sealed in a
closed loop that typically consumes very little water—less than
the amount used in three single-family homes.
clustering: The practice of data centers locating near one
another, connecting their servers to work as a unified system, or
both.

colocation data centers: Multi-tenant data centers where
third-party operators (developers) lease data center space—a
certain number of server cabinets, for example, or kilowatts (kW)
to a host of other companies.

corporate data centers: Also called enterprise data centers,
these facilities store and process a single organization’s data.
These data centers often store the data of financial institutions—
think American Express or Wells Fargo—that typically own and
operate such facilities themselves, rather than leasing them from
a provider.

data center: A building or campus that houses the
infrastructure that supports the world’s computing functions.
data hall: The rooms in data centers where data is processed
and stored.evaporative cooling: A cooling system that uses large fans
to move air across a wet medium to evaporate water, which
removes the heat from the data center and cools the air.

hyperscale data centers: Large data center buildings or
campuses that process and store the data of companies that
often need to scale up or scale down their infrastructure quickly.

hyperscaler: A company that occupies and operates a large
data center building or campus. These companies—which
include AWS, Microsoft, Google and Meta, often need to “scale
up” their infrastructure quickly.

latency: The time it takes for information to travel from its
source to its destination.

load balancing: The process of distributing network traffic
across multiple servers at interconnected data centers.

node: An individual server in a cluster of servers.

phasing: A process for data center campus construction that
occurs in stages.

power distribution units (PDUs): Devices that distribute
energy to servers, network devices, and other equipment within
a rack.

power purchase agreements (PPAs): An agreement between
a data center company (the buyer) and a renewable energy
provider (the seller) to purchase electricity from specific wind or
solar farms.

purple pipe system: A recycled water setup whereby water is
treated to remove contaminants, solids, and impurities and then
distributed via plum-colored pipes.
renewable energy certificate (REC): A tradable commodity
wherein each REC equates to the generation of 1 MWh of power
from a qualified renewable resource, usually wind or solar power
generation facilities.

switch: A device used to connect network devices and route data
through interconnected networks.

switchgear: Power distribution equipment that controls,
protects, and distributes electrical power throughout the data
center.

telecom data centers: Where traffic from cell towers
“switches” to go out to the internet. Typically owned by such

telecommunications companies as Verizon, these centers tend to
be smaller facilities than the other data center types and require
less than 10 kWs.

uninterruptible power supply (UPS) systems: Electrical
equipment used in data centers to provide battery backup power
in the event of a power outage.
utility substation transformer: A large electrical device in
the electrical yards of a data center campus that steps down
high-transmission voltages from the utility grid to lower, more
manageable medium-voltage levels suitable for distribution
throughout the data center.

water-cooled chiller system: An open-loop pipe system in
which water removes heat from the refrigerant.
wholesale data center: A type of data center where a third-
party developer rents a large portion of the space, the energy
capacity, or both to one company–often, all of it.