This manual establishes minimum requirements for the process of commissioning mechanical systems supporting major fixed command, control, communications, computers, intelligence, surveillance, and reconnaissance (C4ISR) facilities. The purpose of this manual is to provide facility managers the information necessary to plan for and implement commissioning of mechanical systems. The commissioning process (sometimes referred to as “acceptance testing”) includes achieving, verifying, testing, accepting, and documenting that the performance of mechanical systems meets design intent and the owner and occupant needs. Ideally, the process begins at the program phase and lasts at least one year after project-closeout. The commissioning process involves the participation of all parties in the building delivery cycle, including, but not limited to representatives of the owner, designer and appropriate contractors. At project closeout, systems needed for immediate operation of the facility have been tested and are considered acceptable. Upon achieving final acceptance at the conclusion of the post acceptance +period, the last step of the commissioning process, the owner and/or his operating and maintenance (O & M) contractor take over full ownership and responsibility of the mechanical systems.