In construction, commissioning or commissioning process (often abbreviated Cx) is an integrated, systematic process to ensure, through documented verification, that all building systems perform interactively according to the "Design Intent".  The commissioning process establishes and documents the "Owner's Project Requirements (OPR)" criteria for system function, performance expectations, maintainability; verify and document compliance with these criteria throughout all phases of the project (design, manufacturing, installation, construction, startup, testing, and operations).  Commissioning procedures require a collaborative team effort and'should' begin during the pre-design or planning phase of the project, continue through the design and construction phases, initial occupancy phase, training of operations and maintenance (O&M) staff, and into occupancy (for warranty and future re-commissioning).

Historically, “commissioning” as referenced in building design and construction, referred to the process by which the heating, ventilation, and air conditioning (HVAC) systems of a building were tested and balanced according to established standards prior to the Owner's acceptance.  HVAC commissioning, historically, didn't include other, interactive, supporting, or supplemental building systems that did not directly affect the performance of the HVAC systems.

In 2005, the U.S. General Services Administration (GSA) published The Building Commissioning Guide. The guide provides a process for including building commissioning in the planning, design, construction and post-construction phases of a project.

Through energy and water conservation, occupant comfort, life-safety, systems criticality, and technology improvements of building systems became more in demand, and expanded the Owner's performance and technical capability expectation.  The need to improve, integrate, and commission other (and more) systems expanded the scope of Building Commissioning.  In modern facilities, buildings, and systems many of the systems are integrated (directly or indirectly) in operation, affect, need for proper operation, function, control, and sequencing.  This can become very complex, and provide many points of sub-optimal operation, or failure, with all the many systems requiring, or affecting, interaction of each other.

For example, power sources (utility, generation, battery/cell) control and monitoring, air movement control, smoke control, fire suppression, fire alarm, security door egress/evacuation control, elevator control, space containment/infiltration, staging and sequencing of every interacting system, its sub-system, equipment, and components each operating and interacting correctly in every operating Mode (normal, startup, shutdown, maintenance, economy, emergency, etc.).

This list can go well beyond this example, even in the most basic, typical, facility today.  As more building systems are integrated, a deficiency in one component can result in sub-optimal operation and performance among other components and systems.  Through system testing and "integrated systems testing" (IST) verification of all interrelationships, effects, modes of operation, and performance can be verified and documented to comply with the 'Owner's Project Requirements' and Architect/Engineers documented 'Design Intent' performance.

Thus, 'Whole Building Commissioning' (or 'Total Building Commissioning') is the accepted normal/standard, certainly for government and critical facility Owners, but also for conservation and efficiencies to provide a fully verified operational facility.  Partial building commissioning (commissioning only specific equipment, functions, systems) is also still utilized, but the interrelations of many automated systems, as designed, today branch and spider throughout many other systems within even basic buildings.  The Owners Project Requirements and the Architect/Engineers design should clearly identify the scope and expectations of commissioning.

Definition 

The following descriptions of the different types of commissioning comes from California Commissioning Collaborative (CCC), Guide for New Buildings (2006).
"The term commissioning comes from shipbuilding. A commissioned ship is one deemed ready for service. Before being awarded this title, however, a ship must pass several milestones. Equipment is installed and tested, problems are identified and corrected, and the prospective crew is extensively trained. A commissioned ship is one whose materials, systems, and staff have successfully completed a thorough quality assurance process.

Building commissioning takes the same approach to new buildings.  When a building is initially commissioned it undergoes an intensive quality assurance process that begins during design and continues through construction, occupancy, and operations. Commissioning ensures that the new building operates initially as the owner intended and that building staff are prepared to operate and maintain its systems and equipment.

Retro-commissioning is the application of the commissioning process to existing buildings.  Retro-commissioning is a process that seeks to improve how building equipment and systems function together.  Depending on the age of the building, retro-commissioning can often resolve problems that occurred during design or construction, or address problems that have developed throughout the building's life.  In all, retro-commissioning improves a building's operations and maintenance (O&M) procedures to enhance overall building performance.

Re-Commissioning is another type of commissioning that occurs when a building that has already been commissioned undergoes another commissioning process.  The decision to recommission may be triggered by a change in building use or ownership, the onset of operational problems, or some other need.  Ideally, a plan for recommissioning is established as part of a new building's original commissioning process or an existing building's retro-commissioning process."

In practice 

While the practice of Building Commissioning is still fairly new (40 years) in the building construction industry, it has become more (not completely) industry standard practice as building owners require higher expectations of performance and return of investment.  The Commissioning process inherently, and through design, improves the quality of the project from initial planning/design through construction and occupancy.

Building Commissioning is typically led by a recognized professional experienced in commissioning who oversees, leads, and serves as the ultimately responsible individual for the management of the process/program and deliverable in the representation of, or contracted to the Owner/Developer.  Typically identified as the "Commissioning Provider" (CxP).  The "Commissioning Provider" may be a member of the Owner, Engineer, Construction/Project Manager, Contractor, or independent Third Party.  The industry standard most recognized and recommended arrangement is for the CxP to be an Independent Third Party Commissioning Provider (also acronym "CxP") contracted directly to the Owner.  This facilitates a more unbiased performance in the representation of the Owner.  The "Commissioning Provider" may have subordinates/peers who participate directly in his/her oversight and commissioning execution/documentation team.  This team is typically identified as the Commissioning Provider's Team. Of course, there are many variations to this as well. In many cases and ideally, there is an ongoing building enhancing and commissioning program and team for the life of the building. Building commissioning is a quality-focused process necessary for both non-complex and complex modern construction projects.

The breadth of the industry, services, benefits, requirements, documentation, etc. is endless.  Although the basic Cx process, phases, and steps are fairly standard, the variations of project scopes, expectations, special designs; individual intricacies of every differing design, manufacture, interaction; use of every differing design, assembly, component, power, control system, control method, equipment, and system available to the designer, and manufacturers; make every single project's systems and Commissioning Program complex and original.

Service method 

While the service method can vary from owner to owner and project to project, the basic formula for a successful building commissioning process involves a synergy team from pre-design to develop the owner's project requirements (OPR), commissioning scope, and plan including benchmarks for success, review of design documents and checklists for achieving the OPR, development of checklists and verifying a sample of construction checklists and submittals, developing training needs and evaluating training delivered by the contractors, witnessing and verifying construction phase tests, and periodic site observations during the construction phase, and performing commissioning functional testing as the project nears completion.

Commissioning Provider (CxP) 

The commissioning provider (CxP) is generally (and preferably) contracted directly to the building owner to ensure unbiased performance of the CxP. The CxP may be a subcontractor (or employee) of the building owner, architect, or design engineer.

It is recommended that the CxP be contracted early in the project planning stages included in pre-design and design charrettes, and maintained throughout the design, construction, and final acceptance of the project at a minimum. Having the CxP on the team early provides opportunity to identify possible operation, installation, testing, and performance issues long before they become a construction issue. The CxP works closely with the owner's representative, building/facility operating engineer, architect, design engineer, general contractor, and all trade subcontractors. The CxP typically is responsible for leading and managing the project commissioning process (design and/or construction) and works closely with the design, construction, and operation teams in a co-operative work environment that focuses on teamwork throughout the building's design, construction, and post construction.

A CxP's ability to add value to a project is rooted in their ability to create positive working relationships with all parties involved and not pointing fingers when issues arise. It is important that the CxP clearly identifies the communication processes/streams, the project goals and expectations (from the OPR), and the team member responsibilities. A CxP has to be able to give open constructive criticism while also being able to listen attentively. The CxP's primary goal is to provide a completed and properly operating product to the building owner and occupant