Commissioning (Level 5 / IST)

Commissioning is the staged testing process that validates a data center's electrical and mechanical systems perform as designed before the facility is handed over to operations, following a five-level framework widely used across the industry and formalized in ASHRAE and Uptime Institute guidance. Levels 1-2 cover factory and component-level acceptance testing; Level 3 verifies system-level installation; Level 4 confirms integrated system function under normal conditions; and Level 5, the Integrated Systems Test (IST), subjects the fully energized facility to simulated full IT load combined with deliberate failure scenarios — utility loss, generator failure, chiller trip — to confirm the site performs to its rated Tier or redundancy level before any tenant load goes live. IST failures at this stage are far cheaper to fix than defects discovered after a facility is in production.