How do commissioning and retro-commissioning differ?

How do commissioning and retro-commissioning differ?

• A. Commissioning applies to new buildings only; retro-commissioning applies to renovations.
• B. Commissioning applies to new or renovated systems to validate performance; retro-commissioning improves existing building performance by identifying inefficiencies and faults.
• C. They are identical processes.
• D. Commissioning is always completed after occupancy; retro-commissioning before occupancy.

Answer: (B)