Functional Performance Testing and Verification
FPT is the heart of commissioning: documented, repeatable procedures that confirm systems meet the OPR under defined conditions. A good FPT procedure states prerequisites, instrumentation and calibration, step-by-step actions, expected results with tolerances, data-recording forms, and pass/fail criteria. Tests should cover normal operation, part-load and staging, failure modes, alarms, safeties, and interlocks.
Understand test types: component and system-level tests, integrated systems tests (e.g., how HVAC, controls, and fire/smoke functions interact), and seasonal or deferred tests. Traps include testing only at design conditions, skipping failure-mode and alarm verification, using uncalibrated instruments, and changing the test conditions mid-run without documentation. Another trap: treating a passed test as permanent; trends and retesting confirm sustained performance.
Verification extends beyond the test event: review trend logs, confirm setpoints and schedules match the BOD, and check that operators can run the system. Document deviations and their resolution.
Rule of thumb: design the test so a different CxA could repeat it and get the same result. Worked example: for a boiler plant, the procedure verifies lead/lag rotation, staged firing at part load, low-water cutoff safety trip, and alarm annunciation to the BAS, with expected values and tolerances listed for each step, and a retest required if any safety fails.