Data Center Construction Glossary
Definitive reference for data center construction terminology — from power distribution and cooling systems to construction trades and commissioning processes.
Power & Electrical
ATS (Automatic Transfer Switch)
A device that automatically transfers a power supply from the primary source (utility) to a backup source (generator) when it detects a failure. Data centers use ATSs to ensure uninterrupted power to critical loads. Installation and wiring of ATSs is a key scope for electricians on data center projects.
Busway
A prefabricated electrical distribution system used to deliver power from switchboards to individual racks in data center white space. Busway replaces traditional cable and conduit for the final power distribution run, enabling flexible and scalable power delivery. Busway installation is a specialized skill for data center electricians.
Duct Bank
An underground system of conduits encased in concrete that houses electrical cables running from utility substations to the data center. Duct banks protect medium-voltage cables and provide organized pathways for power distribution. Concrete workers and electricians collaborate on duct bank construction.
EPMS (Electrical Power Monitoring System)
A system that monitors electrical power distribution throughout a data center in real time — tracking voltage, current, power factor, and energy consumption at each level of the distribution chain. EPMS requires installation of meters, CTs (current transformers), and network communications wiring by controls technicians.
Generator (Emergency/Standby)
Diesel or natural gas engine-driven generators that provide backup power when utility power fails. Data centers typically deploy multiple generators with N+1 or 2N redundancy. Generator installation involves heavy equipment operators for placement, electricians for power connections, pipefitters for fuel systems, and ironworkers for support steel.
Medium Voltage (MV)
Electrical distribution voltage levels between 1kV and 35kV, commonly 15kV and 35kV in data centers. Medium voltage systems carry power from the utility substation to the data center's main switchgear. MV work requires licensed electricians with specific training and certification — these workers are among the most in-demand in data center construction.
PDU (Power Distribution Unit)
A device that distributes electrical power to IT equipment at the rack level. Floor-mounted PDUs take power from the main distribution and feed individual racks. Rack-mounted PDUs provide the final distribution to servers. PDU installation is a core task for data center electricians, especially during the fit-out phase.
RPP (Remote Power Panel)
An electrical panel that distributes power from a PDU to individual circuits serving IT racks. RPPs are located on the data center floor and provide the final level of overcurrent protection before power reaches the IT equipment. Electricians install and wire RPPs during the electrical fit-out phase.
STS (Static Transfer Switch)
A solid-state device that can transfer an electrical load between two power sources in less than a quarter cycle (approximately 4 milliseconds). STSs are used in data centers to provide seamless power transfer between redundant UPS outputs. Installation requires experienced electricians familiar with mission-critical power distribution.
Switchgear
Electrical distribution equipment that controls, protects, and isolates electrical circuits. In data centers, switchgear operates at medium voltage (15-35kV) and low voltage (480V) levels. Main switchgear receives utility and generator power feeds and distributes power through the facility. Installation is performed by electricians with medium-voltage experience.
UPS (Uninterruptible Power Supply)
A system that provides immediate backup power using batteries when the primary utility power fails, bridging the gap until generators start and stabilize (typically 10-15 seconds). UPS systems maintain continuous power to IT equipment during that transition. Installation involves electricians for power connections and structural support from ironworkers for the heavy battery cabinets.
Cooling & Mechanical
Chilled Water System
A cooling infrastructure that circulates chilled water through pipes from a central plant to cooling units in the data center. The system typically includes chillers, cooling towers, pumps, and piping networks. Pipefitters install and connect the chilled water piping infrastructure during construction.
Containment (Hot Aisle / Cold Aisle)
A physical barrier system that separates hot exhaust air from cold supply air in data center white space. Hot aisle containment encloses the hot aisle; cold aisle containment encloses the cold aisle. Containment improves cooling efficiency by 20-40%. Sheet metal workers fabricate and install containment systems during construction.
Cooling Tower
Equipment that rejects heat from the data center's chilled water loop to the atmosphere through evaporative cooling. Cooling towers are typically installed on the roof or in a yard adjacent to the data center. Heavy equipment operators and pipefitters handle the setting and piping of cooling towers during construction.
CRAH (Computer Room Air Handler)
A large air handling unit designed specifically for data center cooling. CRAHs use chilled water coils to cool the air and distribute it through raised floors or overhead ductwork to the IT equipment. Mechanical trades install CRAHs, including piping connections, ductwork, and electrical hookups.
Dry Cooler
A heat rejection device that uses ambient air (without evaporation) to cool a glycol or water loop. Dry coolers are used in data center cooling systems where water conservation is a priority or in climates where they can operate efficiently. Installation involves pipefitters and sheet metal workers.
Free Cooling (Economizer)
A cooling strategy that uses outside air or water temperatures to cool the data center when ambient conditions are favorable, reducing or eliminating compressor-based mechanical cooling. Free cooling can significantly reduce energy costs. Markets with cooler climates (Portland, Nordics) benefit most from economizer designs.
Liquid Cooling
A cooling method that uses liquid (water, dielectric fluid, or refrigerant) in direct contact with or very close to IT components to remove heat more efficiently than air cooling. Types include direct-to-chip (cold plates on processors) and immersion (servers submerged in dielectric fluid). Liquid cooling is increasingly required for AI/HPC facilities and demands new plumbing and piping skills from the construction workforce.
Direct-to-Chip Cooling
A liquid cooling method where cold plates are mounted directly on heat-generating components (CPUs, GPUs) and coolant circulates through them to remove heat. Direct-to-chip cooling is the primary cooling approach for high-density AI server deployments. Construction requires plumbers and pipefitters to install manifolds, CDUs, and distribution piping to each rack.
CDU (Coolant Distribution Unit)
A device that conditions and distributes liquid coolant from the facility's chilled water system to the liquid cooling loops serving individual IT racks. CDUs manage temperature, pressure, and flow of the coolant. Installation involves pipefitters for water-side connections and electricians for power and controls.
Immersion Cooling
A cooling technique where IT equipment is submerged in a non-conductive dielectric liquid that absorbs heat directly from components. Single-phase immersion keeps the liquid below boiling point; two-phase immersion allows the liquid to boil and condense. Immersion cooling is used for the highest-density AI workloads. Construction requires specialized tank installation, plumbing, and heat exchangers.
Construction & Trades
Controls Technician
A skilled tradesperson who installs, wires, and commissions building management systems (BMS), electrical power monitoring systems (EPMS), and other controls infrastructure. Controls technicians work with protocols like BACnet and Modbus and are critical during the commissioning phase of data center construction.
EMR (Experience Modification Rate)
A metric used by insurance companies to measure a construction company's safety performance relative to the industry average. An EMR below 1.0 indicates better-than-average safety; below 0.85 is considered excellent. Data center clients frequently require staffing partners and contractors to maintain low EMR ratings. Cortex Construct maintains a 0.82 EMR.
Punch List
A list of construction items that need to be completed, corrected, or repaired before a project is considered substantially complete. In data center construction, punch list items can include electrical termination corrections, pipe insulation gaps, labeling deficiencies, and cosmetic fixes. QA/QC inspectors track and manage punch lists during the closeout phase.
Prevailing Wage
A government-mandated minimum wage rate for construction workers on publicly funded or incentivized projects. Prevailing wage rates vary by trade and location and typically exceed market rates. Many data center projects receiving state or local tax incentives are subject to prevailing wage requirements, affecting labor costs and staffing strategies.
Facility Design
MW (Megawatt)
The standard unit for measuring data center capacity, referring to the IT electrical load the facility can support. A typical enterprise data center is 5-20MW; hyperscale facilities range from 50MW to 500MW+. Construction costs are commonly benchmarked as dollars per MW ($7-18M/MW depending on density and type).
N+1 Redundancy
A redundancy design where one additional component is added beyond the minimum needed to support the load. For example, if three generators are needed to support the IT load, an N+1 design deploys four. N+1 is common for data center power and cooling systems. 2N designs (fully duplicated) provide even higher reliability. Redundancy level directly affects construction scope and cost.
Power Density
The amount of electrical power consumed per unit area, typically measured in kW per rack or watts per square foot. Traditional data centers run 8-15kW per rack; AI workloads require 50-100kW+ per rack. Higher power density demands more electrical and cooling infrastructure per square foot, increasing construction complexity and labor requirements.
Pre-Action Sprinkler System
A fire suppression system that requires two triggers before water is released: a detection system activation and a sprinkler head activation. Pre-action systems are preferred in data centers because they reduce the risk of accidental water discharge over IT equipment. Fire protection installers with data center experience are required for proper installation.
PUE (Power Usage Effectiveness)
A ratio measuring data center energy efficiency, calculated by dividing total facility power by IT equipment power. A PUE of 1.0 would mean all power goes to IT; typical data centers range from 1.2 to 1.6. Lower PUE indicates more efficient cooling and power distribution. Construction choices — cooling system design, containment, free cooling — directly impact PUE.
Raised Floor
An elevated floor system in data center white space that creates an underfloor plenum for air distribution and cable routing. Raised floors use adjustable pedestals and modular floor tiles, allowing cold air to be delivered directly to IT equipment. Raised floor installation requires precision leveling — typically performed by specialized laborers or concrete workers who verify flatness tolerances.
Tier Level (Uptime Institute)
A classification system defined by the Uptime Institute that rates data center infrastructure redundancy and reliability. Tier I (basic) through Tier IV (fault tolerant). Higher tier levels require more redundant power and cooling systems, increasing construction scope and cost. Most modern data centers are built to Tier III (concurrently maintainable) or Tier IV standards.
VESDA (Very Early Smoke Detection Apparatus)
An aspirating smoke detection system that continuously samples air through a network of pipes and detects smoke particles at extremely low concentrations — far earlier than conventional smoke detectors. VESDA is standard in data center data halls and requires specialized fire protection installers for pipe routing and system commissioning.
White Space
The area within a data center that houses IT equipment — the server rooms or data halls. White space is measured in square feet and is the primary basis for capacity measurement alongside MW. Construction of white space includes raised floor, containment, power distribution to each rack position, and structured cabling infrastructure.
Clean Agent Suppression
A fire suppression system that uses gaseous agents (FM-200, Novec 1230) instead of water to extinguish fires in data center IT spaces. Clean agents leave no residue and do not damage electronic equipment. Installation requires NICET-certified fire protection installers with experience in pressurized gas suppression systems.
Modular Data Center
A data center constructed using prefabricated modules that are built in a factory and assembled on-site. Modular approaches can reduce construction timelines by 30-50% compared to traditional stick-built methods. Modules may include complete power, cooling, and IT space systems. On-site labor focuses on module placement, utility connections, and commissioning.
Operations & Commissioning
BMS (Building Management System)
A computer-based control system that monitors and manages a data center's mechanical, electrical, and environmental systems. BMS integrates HVAC, power monitoring, fire suppression, and security into a centralized platform. Controls technicians install sensors, controllers, and wiring during the construction phase.
Commissioning (Cx)
The systematic process of verifying that all data center systems — electrical, mechanical, fire protection, and controls — function according to design specifications before the facility accepts live IT load. Commissioning includes integrated systems testing (IST) and typically takes 2-4 months. Specialized commissioning technicians support this critical final phase.
DCIM (Data Center Infrastructure Management)
Software that provides unified monitoring and management of a data center's physical infrastructure — power, cooling, space, and connectivity. DCIM integrates data from BMS, EPMS, and other building systems. Controls wiring and sensor installation during construction enable DCIM functionality.
IST (Integrated Systems Testing)
The final phase of data center commissioning where all systems — electrical, mechanical, fire protection, and controls — are tested together under simulated load conditions. IST verifies that the facility performs as designed when all systems interact. Requires a specialized workforce including commissioning technicians and experienced electricians.
Load Bank Testing
A commissioning procedure that uses temporary resistive loads to simulate the electrical draw of IT equipment. Load bank testing verifies that generators, UPS systems, and the power distribution chain can handle full design load. Electricians and commissioning technicians manage load bank connections and testing procedures.
Industry & Market
Colocation (Colo)
A data center facility where multiple tenants rent space, power, and cooling to house their IT equipment. Colocation providers build the facility and infrastructure; customers bring their own servers. Colo construction often involves phased builds: shell-and-core, powered shell, and customer suite fit-outs.
EPC (Engineering, Procurement, and Construction)
A project delivery method where a single contractor handles engineering design, equipment procurement, and construction under one contract. EPC is common in hyperscale data center builds where owners want turnkey delivery with single-point accountability. EPC firms require large, flexible workforces to execute fast-track schedules.
General Contractor (GC)
The primary construction company responsible for managing the overall data center build. The GC coordinates all subcontractors, manages the schedule and budget, ensures safety compliance, and serves as the owner's main point of contact during construction. Leading data center GCs have dedicated mission-critical divisions.
Hyperscale Data Center
An extremely large data center facility, typically 100MW or more, built and operated by major cloud providers (AWS, Microsoft, Google, Meta) or large technology companies. Hyperscale campuses can span hundreds of acres with multi-year construction programs requiring thousands of workers. These projects drive the majority of data center construction labor demand.
Edge Data Center
A small-scale data center located close to end users or data sources to reduce latency and improve performance. Edge facilities typically range from a few hundred kW to 5MW. They are often built using modular or prefabricated methods and require compact, multi-skilled construction crews for rapid deployment.
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