Which type of commissioning is defined as being for the first time?

The correct choice refers to the term that specifically signifies the process of commissioning a system or facility for the first time, ensuring that it operates as intended according to the design specifications. This process typically involves rigorous testing and adjustments during the startup phase to ensure that all systems function properly and work together harmoniously.

The other types of commissioning differ in significant ways. Recommissioning typically refers to the process of reassessing and optimizing existing systems that have already been commissioned. Retrocommissioning involves improving the performance of a building, often due to technological upgrades or identifying inefficiencies in systems that were not initially considered during the original commissioning. Continuous commissioning, on the other hand, is a proactive approach that involves ongoing monitoring and adjustments of building systems to maintain optimal performance over time.

Thus, the definition that pertains to commissioning a system for the first time indeed aligns specifically with the concept of retrocommissioning, confirming it as the correct answer.