At mission critical facilities, data management has become increasingly important in today's world requiring 100% uptime of the facility electrical and mechanical systems. As a result, flawless operation of the building systems is essential in all conceivable modes (normal, maintenance, and failure). Commissioning is the process of identifying, documenting, performing and perfecting the operation of the entire building electrical and mechanical systems in all of these operational modes. Large projects always involve many manufacturers and many operating systems with individual goals and proprietary controls.

To ensure a cohesive building operating system, the commissioning agent must systematically identify and describe all anticipated operating modes and conditions, along with the undesirable and possibly unanticipated operating conditions. Then, all modes must be executed while system responses and interactions are evaluated and documented. Weaknesses and interface problems are identified and addressed, and operation of the final project is again performed and documented as a seamless, predictable operating unit. For large data/telecommunication facilities, the electrical and mechanical systems are very complex, with automation, redundancy, and maintainability built in to almost all aspects of every system. It can be a daunting task merely to document the various operating modes and conditions and identify the many interface requirements between vendors and systems. Performance of the process is always lengthy and complex and is often performed around the clock or at off hours to benefit all of the trades and contractors involved.