Data centre commissioning: levels 1 to 5, IST and the records behind them
Deskely Completions team Singapore
Data centre commissioning proves that the power, cooling, fire and control systems of a data hall do what the design says, including when things fail. It is usually organised in five levels, from witnessing tests at the factory to an integrated systems test (IST) in which utility power is cut and the whole facility has to ride through.
This guide covers the five commissioning levels, the integrated systems test, who is involved, the documents that drive and record the work, and how to keep thousands of tests and issues under control on a large build.
- Commissioning runs in five levels: factory tests, installation checks, start-up, functional tests, integrated systems test.
- The integrated systems test proves the facility rides through failures such as a utility outage.
- The owner's project requirements and basis of design define what "working" means.
- Every test, issue and sign-off belongs to an asset; that is what makes the final handover credible.
The five commissioning levels
| Level | Name | What happens |
|---|---|---|
| L1 | Factory witness testing | Key equipment (generators, UPS, switchgear, chillers) tested at the factory before shipping, often witnessed by the owner |
| L2 | Delivery and installation verification | Equipment checked on arrival and inspected as installed against the drawings and submittals |
| L3 | Pre-functional checks and start-up | Pre-functional checklists completed, equipment energised and started up, often by the vendor |
| L4 | Functional performance testing | Each system tested through its sequences of operation, alarms and failure modes |
| L5 | Integrated systems testing (IST) | All systems tested together under load, including loss of utility power and failover |
The level names and scopes vary between owners and commissioning agents, but the progression from single pieces of equipment to the whole facility is common to almost all of them.
Integrated systems testing (IST)
The IST is the final proof. With load banks simulating the IT load, the team cuts utility power and checks that the UPS carries the load, the generators start and take over, the transfer switches and switchgear operate in sequence, the cooling keeps the hall within limits, and everything returns cleanly when utility power comes back. Further scenarios test single failures in redundant paths, so that an N+1 or 2N design proves its redundancy.
The IST is scripted in advance, step by step, with acceptance criteria for each step, and recorded as it runs, including temperatures, voltages and timings. Any failure becomes an issue to fix and, usually, a retest.
Who is involved
- Owner or operator: sets the requirements and accepts the facility.
- Commissioning agent or authority (CxA): independent of the contractor in many projects; writes the plan and scripts, witnesses and reports.
- General contractor and trade contractors: install, complete checklists and fix issues.
- Equipment vendors: start-up and factory tests for their equipment.
- Designers: the basis of design, and answers when tests show a design issue.
Documents that drive commissioning
| Document | Purpose |
|---|---|
| Owner's project requirements (OPR) | What the owner needs the facility to achieve |
| Basis of design (BOD) | How the design meets the OPR |
| Commissioning plan | Scope, levels, roles, schedule and procedures |
| Pre-functional checklists | Installation and start-up checks per piece of equipment (L2 and L3) |
| Functional test scripts | Step-by-step tests of each system (L4) |
| IST scripts | Scenario-by-scenario tests of the whole facility (L5) |
| Issues log | Every deficiency found, with owner and status |
| Commissioning report | The evidence package at handover |
Many data centre owners also follow ASHRAE Guideline 0 and the Uptime Institute's tier requirements; commissioning practice on mission-critical facilities draws on both.
Why data centre commissioning gets hard to track
A hyperscale or colocation campus repeats the same building blocks many times: dozens of generators, hundreds of UPS modules and cooling units, thousands of breakers and sensors. Each has its checklists, tests and issues, and phases overlap as halls are completed one after another. Spreadsheets and shared folders break down quickly: the same asset is tracked in several files, issues lose their link to the test that raised them, and nobody can say what still stands between a hall and its IST.
The answer that works on any large capital project is the same: one register of every asset, with every checklist, test, issue and certificate held against it, rolled up by system and by hall. See commissioning 101, the commissioning checklist and the single line diagram guide for the electrical side.
Deskely for data centres
Deskely comes from FPSO completions, where tens of thousands of tags across hundreds of subsystems are commissioned in parallel. The same structure fits a data centre: assets by hall, system and subsystem; checklists and functional tests on tablets against each asset; issues raised in the field with photos and tracked to closure; and live progress per hall towards IST and handover.
The Deskely products for this
Frequently asked questions
What are the levels of data center commissioning?
Usually five: L1 factory witness testing, L2 delivery and installation verification, L3 pre-functional checks and start-up, L4 functional performance testing and L5 integrated systems testing.
What is IST in data center commissioning?
Integrated systems testing: all the facility's systems tested together under simulated load, including loss of utility power, generator start and transfer, and failures in redundant paths.
What is a commissioning agent?
The person or firm responsible for planning, scripting, witnessing and reporting commissioning, often independent of the contractor and working for the owner.
What is the difference between L4 and L5 commissioning?
L4 tests each system on its own through its sequences and failure modes. L5 tests all systems together as one facility.
How long does data center commissioning take?
It depends on the size and phasing of the build. Commissioning runs alongside construction from factory tests onward, with the integrated systems test at the end of each phase or hall.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016