- Critical load vs IT load
- IT load is the power drawn by servers, storage and network gear. Critical load is everything the UPS and generators must carry, including IT plus the mechanical and control systems that keep it alive. Leases are written against one or the other, and confusing them misprices a deal.
- MW of critical capacity
- The unit the industry actually trades in. Watch which megawatt is quoted: design capacity on paper, IT capacity sellable to tenants, and installed or energized capacity ready to power a rack today are three different numbers, and announced campus totals are usually the first.
- kW per rack / rack density
- Power drawn by a single cabinet. Traditional enterprise colocation ran 3-8 kW; modern AI training racks run an order of magnitude higher. Density, not floor area, determines whether a hall can host a workload at all.
- PUE (power usage effectiveness)
- Total facility energy divided by IT equipment energy, popularized by The Green Grid. A PUE of 1.0 would mean every watt reaches the servers. It is the industry's headline efficiency metric and also its most gamed one — always ask about annualized, whole-facility, at-load measurement.
- WUE (water usage effectiveness)
- Litres of water consumed per kilowatt-hour of IT energy. Evaporative cooling trades electricity for water, so a very low PUE can hide a very high WUE — a live tension in drought-exposed Texas.
- CUE (carbon usage effectiveness)
- Kilograms of CO2 equivalent per kilowatt-hour of IT energy. Unlike PUE it depends on the grid mix and the hours you consume, which is why 24/7 matching and CUE tend to be discussed together.
- N+1 and 2N redundancy
- N is the capacity needed to carry the load. N+1 adds one spare unit; 2N duplicates the entire system on independent paths; 2N+1 adds a spare to each. Redundancy is what you pay for when you buy uptime, and it multiplies both capex and footprint.
- Uptime Institute Tier I-IV
- The reliability classification buyers speak in: Tier I basic capacity, Tier II redundant components, Tier III concurrently maintainable, Tier IV fault tolerant. Uptime certifies Design Documents, Constructed Facility and Operational Sustainability separately — a 'Tier III design' is not a certified Tier III building.
- Concurrent maintainability
- The Tier III property: any capacity component or distribution path can be taken out of service for planned maintenance without dropping IT load. It is about planned work, not failures.
- Fault tolerance
- The Tier IV property: a single unplanned failure anywhere in the power or cooling system does not affect IT load, with compartmentalization and continuous cooling. Far more expensive, and genuinely required by fewer workloads than sales decks imply.
- UPS topology
- How the uninterruptible power supply is configured — double conversion (online), line interactive, eco or multi-mode, plus distributed-redundant and block-redundant architectures, and battery versus rotary flywheel. The topology sets both efficiency and the failure modes you inherit.
- Static transfer switch (STS)
- A solid-state switch that moves a single-corded load between two independent power sources in milliseconds, letting single-power-supply equipment sit on a dual-path design without dropping.
- Generator runtime and fuel contracts
- Standby generators are sized for the critical load, but the real questions are on-site fuel storage hours, refueling contracts with guaranteed priority delivery, load-bank testing cadence, and air permit limits on runtime hours.
- Utility interconnection and the large-load queue
- The formal process for connecting a very large new load to the transmission or distribution system: studies, capacity confirmation, facility upgrades and an energization date. In ERCOT the large-load process is the gate every Texas project passes through, and queue position now determines project viability more than site quality.
- Load ramp schedule
- The agreed curve of how quickly a campus draws its contracted megawatts — often stepped over years. Utilities plan generation and transmission against it, and tenants pay for capacity they have not yet filled.
- Curtailable and interruptible load
- Capacity a data center agrees to reduce on demand, in exchange for faster interconnection, lower rates or both. Once considered incompatible with data centers, it has become a mainstream way to get connected sooner in constrained grids.
- Demand response participation
- Programs that pay large loads to shed or shift consumption during scarcity events. Data centers participate via generators, batteries, workload shifting or shutting down flexible compute, turning a cost center into a grid asset.
- Behind-the-meter generation
- Generation sited on the customer's side of the utility meter — gas turbines, reciprocating engines, fuel cells, solar, storage and prospectively small modular reactors — used to bypass interconnection delays or firm up supply. Regulatory treatment varies sharply by state.
- PPA and VPPA
- A power purchase agreement contracts for physical delivered energy; a virtual PPA is a financial contract-for-difference that transfers renewable energy certificates without moving electrons. VPPAs are how most data center renewable claims are actually made.
- 24/7 carbon-free energy vs annual matching
- Annual matching buys enough clean generation over a year to offset total consumption. 24/7 CFE requires clean supply in every hour on the same grid. The gap between the two is the honest measure of a sustainability claim.
- Substation build and transmission cost allocation
- A large campus usually needs a dedicated substation and often transmission upgrades. Who pays — the developer, the utility, or ratepayers through the rate base — is the central regulatory fight in every fast-growing data center market.
- Air cooling and economization
- Moving heat with air, using outside air or water-side economizers to run chillers less when ambient conditions allow. Cheap and well understood, but it hits a practical ceiling around the low tens of kilowatts per rack.
- CRAC vs CRAH
- A CRAC is a computer room air conditioner with its own refrigerant compressor. A CRAH is a computer room air handler using chilled water from a central plant. CRAHs dominate at scale; CRACs suit smaller or distributed rooms.
- Hot aisle / cold aisle containment
- Physically separating supply and return air with doors, roofs or chimneys so hot exhaust cannot mix with cold supply. The single highest-return efficiency retrofit in most legacy halls.
- ASHRAE thermal envelope
- The recommended and allowable temperature and humidity ranges for IT equipment published by ASHRAE Technical Committee 9.9, with equipment classes A1-A4 and newer high-density and liquid-cooling classes. It is the reference every operator cites when raising setpoints to cut cooling energy.
- Chilled water plant and dry coolers
- Chillers, pumps, piping and cooling towers producing chilled water for CRAHs or CDUs. Dry coolers reject heat to ambient air without evaporating water — more electricity, far less water, and increasingly chosen in water-stressed regions.
- CDU (coolant distribution unit)
- The heat exchanger and pumping skid that isolates the facility water loop from the technology loop feeding cold plates, controlling flow, pressure and temperature. It is the interface component that makes a hall liquid-ready.
- Direct-to-chip liquid cooling
- Cold plates mounted on CPUs and GPUs carry heat away in liquid while air handles the rest of the server. The mainstream path to high-density AI racks because it retrofits into existing halls more readily than immersion.
- Immersion cooling
- Submerging entire servers in dielectric fluid, single-phase or two-phase. Very high heat capture and excellent efficiency, but it demands different racks, service procedures, fluid handling and vendor warranty support.
- Rear-door heat exchanger
- A liquid-cooled coil replacing the rack's rear door, capturing heat as air leaves the cabinet. A pragmatic middle step that raises achievable density without re-plumbing the servers themselves.
- Water consumption and reclaimed water
- Evaporative and adiabatic cooling consume water; closed-loop and air-cooled designs largely do not. Reclaimed, non-potable or effluent water sourcing is now a standard permitting condition in Texas and a routine community question.
- Retail colocation
- Selling by the cabinet, cage or partial rack with power measured in kilowatts, bundled with interconnection and remote hands. Higher margin per kW, shorter terms, and sold to enterprises and network operators.
- Wholesale colocation
- Leasing dedicated halls or suites by the megawatt on long terms, with the tenant handling its own IT fit-out. Lower margin per kW, far larger deals, and the format hyperscalers and AI companies actually buy.
- Build-to-suit and hyperscale self-build
- A developer builds a campus to a single tenant's specification under a long pre-lease, or the hyperscaler buys the land and builds it themselves. Self-build gives control and lowest long-run cost; leasing gives speed, which in a power-constrained market often wins.
- Retail colo cabinet pricing
- Typically a monthly recurring charge per cabinet for space plus a committed kW of power, with metered power billed as pass-through or included to a cap, then cross-connects, remote hands and bandwidth on top. Comparing quotes requires normalizing all of it to dollars per kW.
- Cross-connect and interconnection revenue
- Fees for physical circuits between tenants inside a facility. Individually small, collectively the highest-margin recurring revenue in retail colocation, and the reason dense carrier ecosystems are so defensible.
- Meet-me room (MMR)
- The neutral room where carriers, networks and tenants physically interconnect. Its carrier count and diversity are the clearest measure of a facility's network value.
- Carrier neutrality
- The operator sells no transport of its own and lets any network in on equal terms. It is what makes a meet-me room worth joining, and it distinguishes independent colocation from telco-owned facilities.
- Cloud on-ramp
- A private, dedicated port into a public cloud — AWS Direct Connect, Azure ExpressRoute, Google Cloud Interconnect, Oracle FastConnect — available inside the facility. On-ramp presence is a primary site-selection criterion for hybrid architectures.
- Latency and edge
- Round-trip time between user or device and compute, bounded by distance and hops. Edge deployments exist to defend a latency budget or to keep data local; where neither applies, 'edge' is usually a marketing label on a regional facility.
- Powered shell
- A completed building with utility power, substation and structure delivered, but without mechanical and electrical fit-out. Sold or leased to tenants who want to install their own MEP, and a common way to shorten time to energization.
- Land banking
- Acquiring and holding sites with credible future power for later development. In practice developers are banking interconnection positions and utility relationships as much as dirt.
- Entitlement and zoning for data centers
- Rezoning, special use permits, site plan approval, noise ordinances, setbacks, water and wastewater commitments and traffic studies. Entitlement risk has risen sharply as local opposition organized, and it now belongs on the schedule alongside interconnection.
- Chapter 380/381 abatement (Texas)
- Texas Local Government Code Chapter 380 lets municipalities and Chapter 381 lets counties offer economic development agreements, commonly structured as partial property tax rebates over a term. These local agreements, not state incentives, are where most Texas data center tax negotiation actually happens.
- Texas data center sales tax exemption
- Texas exempts qualifying data center equipment from state sales and use tax for certified projects that meet statutory thresholds for facility size, capital investment, permanent job creation and wage level, with a longer term available to larger qualifying large data center projects. Certification runs through the Texas Comptroller — always confirm current thresholds against the Comptroller's published rules rather than a summary.
- Long-lead equipment
- Large power transformers, medium-voltage switchgear, generators, chillers and UPS modules with order-to-delivery times now measured in many months to years. Procurement is placed before design is finished, and equipment slots have become tradeable assets.
- Commissioning Levels 1-5
- The staged proof that a facility works: factory acceptance (L1), component verification on site (L2), pre-functional and point-to-point checks (L3), functional performance of each system (L4), and integrated systems testing of the whole facility under simulated load and failure (L5). Level 5 is where design assumptions get falsified before a tenant moves in.
- SLA and uptime credits
- The contractual availability commitment and the service credits owed when it is missed. Credits are almost always capped at a share of the monthly recurring charge, so they are a signal of confidence rather than real compensation for a business outage — read the exclusions.