Plain-English guide · last changed 13 September 2026

How a data center works—and what its numbers mean.

A data center is a building full of computing equipment plus the electrical, cooling, water, network and backup systems that keep it running. The hard part is not the definition. It is keeping unlike projects and measurements from being treated as the same thing.

The short version

Servers do the computing. Electrical systems deliver and condition power. Cooling systems move heat away. Networks move data. A campus can contain several buildings built in phases, so one announcement is not automatically one operating facility.

One site can produce several different counts

A project is a development effort. A campus is a site that may contain several buildings. A building is one physical structure. An operating facility is a building or bounded site supported as operating. A provider presence can be only a tenant suite inside someone else’s facility.

Those units can overlap. Adding them together double-counts the same physical place. That is why DataCenterData keeps its record units and counting rules visible.

Power and energy are not the same number

A megawatt (MW) is a rate of power at a moment. A megawatt-hour (MWh) is energy used over time. A utility-service request, contracted capacity, anticipated site demand, critical IT load, backup-generator rating and measured grid load are different measurements. They should not be silently substituted or added.

Power reaches the computing equipment through substations, transformers, switchgear and power-conditioning equipment. Some electricity also runs cooling and other support systems. Power usage effectiveness, or PUE, compares total facility energy with IT-equipment energy; it does not reveal a site’s total electricity use by itself. For national context, see the U.S. Department of Energy data-center resource hub.

Cooling moves heat; the water result depends on the design

Computers turn most of the electricity they use into heat. Air cooling, direct-to-chip liquid cooling and immersion cooling move that heat in different ways. Heat can ultimately be rejected with dry coolers, chillers, cooling towers or a combination.

“Closed loop” usually describes recirculation inside part of the system. It does not, by itself, prove zero withdrawal or zero consumption. Withdrawal, consumption, discharge, make-up water, potable water, reclaimed water and avoided potable use are separate measures. Climate, grid mix, server efficiency, utilization and cooling design all affect the result; Berkeley Lab’s water-use review explains why there is no single universal number.

Open the cooling and water evidence →

A project moves through stages

Announced means someone described a plan. Proposed means review or approval is still pending. Approved means a named approval exists, not that construction began. Construction requires evidence of physical work. Operating requires evidence that the facility or a defined phase entered service. Withdrawn, expired and closed projects stay in the history instead of disappearing.

Jobs, taxes and incentives need denominators

Peak construction workers, construction job-years, permanent employees and contractors are different quantities. Announced investment is not completed investment. A tax exemption, abatement, payment in lieu of taxes, special charge and gross tax receipt affect different ledgers. A useful local-outcome claim states the place, period, payer, recipient and whether the figure is authorized, promised, paid or observed.

Read the jobs brief → · Read the incentives brief → · Read the ratepayer brief →

How to read a DataCenterData claim

  1. Read the exact statement and who made it.
  2. Check the unit, place, scope and date.
  3. Open the cited source and its page, clause or record locator.
  4. Read what the source supports—and what remains unknown.
  5. Check the verdict date and visible correction history.
Unknown is not zero.

A missing operating record does not prove that a site is closed. A permit does not prove use. A company announcement proves that the company made the statement, not that the future outcome has occurred.

Browse the claim ledger → · See corrections and lifecycle changes →