Which term is used to describe commissioning activities in existing buildings aimed at diagnosing ongoing problems or supporting planned maintenance?

• A. Retro-Commissioning
• B. Re-Commissioning
• C. Initial Commissioning
• D. Decommissioning

Answer: (A)

Retro-commissioning is the process applied to a building that is already in operation, focusing on diagnosing problems that have developed over time and supporting planned maintenance. It starts from how the building actually operates rather than how it was designed, identifying faults, miscalibrations, and control sequence issues that affect performance, comfort, or energy use. The goal is to tune and adjust existing systems so they run more reliably and efficiently, with maintenance planning informed by actual operating conditions.

This distinguishes it from initial commissioning, which is done for new buildings to ensure systems are installed and tested correctly; from re-commissioning, which involves repeating the commissioning process after significant changes, and from decommissioning, which means shutting down or removing systems. The focus on an existing building, diagnosing current problems, and supporting maintenance makes retro-commissioning the correct term.