HVAC commissioning in existing buildings is described as re-commissioning when it is used to diagnose ongoing problems or support a planned preventive maintenance program. Which term is this?

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

Answer: (B)

Re-commissioning is applying the commissioning process to an existing building to verify and improve how its systems perform, especially when problems persist or there’s a plan to support ongoing maintenance. It focuses on diagnosing faults, tuning controls, and validating that equipment operates as intended under current operating conditions, which fits exactly when HVAC issues are ongoing or when a systematic preventive maintenance program needs solid, verified performance data. This differs from initial commissioning, which is done on new construction; retro-commissioning, which addresses performance gaps in existing buildings that may not have been commissioned originally; and decommissioning, which is about retiring or removing a system.