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Commissioning guide

The five levels of data center commissioning

Commissioning is the staged quality process that proves a facility works as designed — and survives failures — before any IT load arrives. The industry structures this as Levels 1 through 5, from factory acceptance testing to the integrated systems test that gates go-live.

A note on terminology: the names, numbering and acceptance criteria of the commissioning levels are not standardized. They vary by provider, by contract and by project practice — one organization's Level 3 may be another's Level 2, and some programs use different labels entirely (e.g. provider-specific phase names). What matters is that the intent of each gate — and its sign-off — is clearly defined in your commissioning plan, whatever it is called.

Level 1

Factory Acceptance Testing (FAT)

Equipment is tested at the manufacturer's facility before it ever ships to site.

  • Witnessed tests on switchgear, UPS systems, generators, chillers and CRAH/CRAC units against the approved submittals and the basis of design.
  • Catches defects, wiring errors and control-logic issues while they are still cheap and fast to fix — no site logistics, no schedule pressure.
  • Produces the FAT report and punch list that become the baseline for everything that follows on site.

Gate to pass: equipment performs to specification and the punch list is closed or formally carried forward.

Level 2

Site Delivery & Installation Verification

Equipment arrives on site and is verified against what was actually approved and tested at the factory.

  • Receiving inspections confirm the delivered equipment matches the FAT'd configuration — model, firmware, options and settings.
  • Installation is checked against drawings and manufacturer requirements: clearances, torque, terminations, labeling, grounding.
  • Damage in transit, missing components and storage non-conformances are logged before they become someone else's problem.

Gate to pass: equipment is installed per design, documented, and ready to be energized or started safely.

Level 3

Pre-Functional & Component Testing

Individual components and subsystems are started up and checked in isolation — the static checks before anything runs as a system.

  • Point-to-point verification of sensors, actuators, breakers, valves and controls I/O against the controls matrix.
  • Start-up and pre-functional checklists executed per system: rotation checks, safeties, interlocks, alarms, BAS/BMS point mapping.
  • This is where most issues are found — and where disciplined logging keeps them from resurfacing at Level 5.

Gate to pass: every component and subsystem works standalone, with pre-functional checklists complete and deficiencies logged.

Level 4

Functional Performance Testing (FPT)

Complete systems are tested through their full operating sequences under realistic load.

  • Scripted tests exercise each system end-to-end: normal operation, standby transfer, alarm response, failover and restart.
  • Load banks simulate IT load so electrical and cooling systems can be proven at design capacity before any servers arrive.
  • Every test script is written, reviewed and approved before it runs — results are witnessed and signed off, not asserted.

Gate to pass: each system meets its functional performance criteria across normal and failure-adjacent scenarios.

Level 5

Integrated Systems Testing (IST)

The final gate: all systems are tested together, proving the facility survives real failure scenarios as one integrated whole.

  • Utility loss, generator start and transfer, cooling ride-through and recovery — executed as coordinated, scripted failure scenarios.
  • Confirms the design intent under the conditions that actually cause outages: the interactions between systems, not the systems themselves.
  • Produces the definitive evidence package for handover, operations readiness and any Tier certification or SLA commitments.

Gate to pass: the facility demonstrates its design-basis failure response end-to-end, with the issues log closed or risk-accepted by the owner.

What makes the framework work

Each level is a gate — signed off before the next begins, so risk never compounds downstream.

The commissioning plan, not the level number, defines scope: numbering conventions vary by program, the discipline does not.

Every test is scripted before it runs, and every result is witnessed, logged and traceable.

The issues and deficiency log is the single source of truth from L1 through handover.

This framework aligns with industry practice referenced by ASHRAE (Guideline 0, Standard 202 and TC 9.9 guidance for mission-critical facilities) and the commissioning methodologies used across hyperscale and colocation programs.

Planning a commissioning program?

We build the schedules, trackers and reporting that keep every commissioning gate visible — from FAT witness trips to IST sign-off.

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