Services & Maintenance: Commissioning For Existing Facilities

Cracking at building corners. (Photo:
Cracking at building corners. (Photo:

By Jim Magee and Ray Bert
From the July 2008 issue of Facility Executive magazine

While commissioning of new buildings often gets more attention, commissioning of existing structures represents a significant opportunity for facility managers (fms) to improve performance. In many cases, this effort will also enable fms to save significantly on energy and ongoing maintenance costs.

Commissioning for existing buildings differs from that for new construction in several important ways. New construction commissioning typically proceeds as a component of the design and construction of a facility, executed by the project team for acceptance by the facility’s management.

By contrast, existing building commissioning requires active involvement from the fm (along with support from occupants) in order to develop a plan, form a team, and then execute the process outlined in the plan. Commissioning carried out after building occupancy also involves special issues that are not relevant when dealing with new construction.l

Fms often procure the consulting services of an independent, third party commissioning firm to work closely with them throughout the process. The phases and typical activities involved in commissioning of existing buildings include planning, implementation, and corrections.

Planning Phase

Commissioning goals. Existing building commissioning arises from the need to resolve ongoing problems or to ensure that functionality continues to meet facility needs. Often, fms may elect to implement commissioning before deciding on a complete redesign and renovation of building systems; recalibration, reconditioning, or reprogramming of existing installations can sometimes solve problems with less expense than replacement.

Select a commissioning team. Typically, an fm solicits proposals for the services from several agencies. For a redesign or renovation, the fm may retain a design firm that includes a commissioning authority on its team, or decide to contract directly with a commissioning agency that includes a design professional as part of the commissioning staff.

In preparing the request for proposal, the fm should provide information about the goals and systems to be included in the scope of work. The commissioning agency may propose a suitable solution to the fm based on the information gathered from an initial interview, and responsibilities of both the agency and the facility personnel must be defined clearly from the outset.

The commissioning agency then works with the fm to determine who should be on the team. Members may be contractually attached to the facility, the commissioning agency, or a contractor entity, depending on the facility’s preference and the project goals. Potential team members include:

  • The fm;
  • Maintenance personnel;
  • Commissioning authority (CxA);
  • Design consultants;
  • Construction/general manager;
  • Mechanical contractors;
  • Electrical contractors;
  • Test and balance (TAB) contractors;
  • Building automation system (BAS) contractors;
  • Equipment vendors;
  • Specialty trades, vendors, and/or consultants;
  • Service contract providers; and/or
  • IT support groups.

Existing building commissioning scope. This effort requires detailed meetings between the fm and his or her commissioning team, as well as input from the operations and maintenance (O&M) staff and building occupants. The scope of the work to be done is based on these discussions and input from the team members and should be finalized as soon as possible.

The final scope should include roles and responsibilities of team members, sequence and coordination of actions to be performed by team members, required manufacturer literature, and an initial schedule. This scope should be incorporated into a plan prepared by the CxA or the fm.

Documentation and site reviews. The fm, the CxA, and other team members review existing documentation and inspect installations and existing conditions, often as part of the initial team meeting. If the information at hand is unavailable, incomplete, or inaccurate, reasonable efforts should be made to create a database of complete and accurate documentation. Data can sometimes be found in the design consultant’s records or in manufacturer’s/supplier’s data, and equipment information can often be located online. The basis of design information may have to be obtained from a site survey, if the original is not available.

Commissioning Plan. Next, the CxA or the fm prepares a commissioning plan, which will contain functional performance test checklists detailing the test procedures to be used, with clear delineation of pass/fail criteria. The plan should also include any special considerations for dealing with occupied building conditions. Schedules and a list of the commissioning team members (along with their contact information, roles, and responsibilities) are also key features of the plan.

Implementation Phase

Testing services. If a testing agency, such as a test and balance firm, is part of the team, it may be used for initial analysis of building systems performance. Testing agencies document work performed on approved data sheets and drawings as required by the plan. The CxA or the fm may employ sampling or demonstration methods to validate test report data.

Functional performance tests. The team conducts functional performance tests for building systems included within the scope, with results thoroughly documented. The O&M staff or a BAS contractor should work with the commissioning agency to operate systems as required for testing.

Analyze results. The commissioning agency, the fm, and consultants analyze the functional performance tests to determine if systems are operating according to requirements. If deficiencies are identified, corrective measures should be planned.

Review O&M practices. Members of an O&M staff may occasionally modify important controls or equipment operations in well intentioned attempts to address complaints. However, this can compromise overall system performance.

The fm should evaluate O&M staff practices throughout the commissioning process and ensure that personnel understand how building systems are intended to operate, including all modes and sequences of control. Based on this review, the fm can develop modifications of the O&M training program.

Commissioning report. The fm or the CxA prepares and submits a report, including an executive summary to highlight major findings.

Maintaining Building Health

With the implementation phase completed and a report showing the current status of all systems in the scope of work, the team can begin making any needed modifications to achieve optimal performance. These modifications should be performed using a systematic, iterative approach that repeats the steps of functional performance testing, analysis of results, and reporting.

Systematic and coordinated application of existing building commissioning offers the fm opportunities to establish optimal performance. In addition to improving day-to-day performance and efficiency, the process often improves performance to an extent that obviates the need for more expensive renovations or equipment replacement. In other cases, renovation projects may still follow, but as a result may be more focused and less costly, thanks to finely defined goals and objectives resulting from the commissioning process.

Magee is president of AABC Commissioning Group (ACG), a Washington, DC-based nonprofit association of certified, independent commissioning authorities. He is also president of Facility Commissioning Group, a certified commissioning firm headquartered in Nicholasville, KY. Bert is associate executive director of ACG.

Commissioning Terminology

A variety of somewhat ambiguous terms are used in the industry to refer to the commissioning of existing buildings. Here is a brief primer on common definitions for three often used terms.

Retro-Commissioning (RetroCx): Commissioning an existing building that has never been commissioned.

Re-Commissioning (ReCx): Commissioning a building that has been previously commissioned.

Ongoing or Continuous Commissioning (CCx): Commissioning that continues to collect and compare baseline data on selected building systems to ensure that the building functions optimally throughout its operating life after construction acceptance and warranty.

However, Craig Hawkins of CHDS-Commissioning, a commissioning services provider in Auburn, WA, insists that because the prefix retro is often used to mean designating the style of another time, or backward2, the term retrocommissioning may be confusing and offers little descriptive benefit to commissioning terminology.

A more pragmatic approach might be to consider commissioning as either: New Construction Commissioning (NCCx): Commissioning a new building or building addition; or Existing Building Commissioning (EBCx): Commissioning an existing building.


1ACG Commissioning Guideline, AABC Commissioning Group; Washington, DC; 2005;

2Existing Building Commissioning…must we call it Retro?; 2006 SERBCA-CCBCA Fall Seminar Presentation; Craig Hawkins; CHDS-Commissioning; Auburn, WA; 2006.