Re-commissioning of an existing building presents unique challenges. When the building is an occupied laboratory the complications are compounded. Occupied laboratory commissioning can only be successful with extensive upfront document review and field verification. Extensive site access and room-by-room scheduling, as well as schedule shift and delays, must be anticipated. If the building being commissioned is part of a campus district energy system, the project scope needs to include discussions with central plant staff and may even need to include some review of related utility systems on campus.