Existing Building Commissioning: Retro-commissioning and Re-commissioning with EAB

EAB commissioning professionals doing on site systems check

Existing Building Commissioning (EBCx) can typically be separated into two categories, Retro-commissioning and Re-commissioning. Retro-commissioning is the process of commissioning a facility that has been completed and turned over to a client, and potentially occupied, but was never commissioned during its initial construction. Alternatively, Re-commissioning is the process of commissioning a facility that was previously commissioned but requires additional commissioning services for reasons including, but not limited to, a change in tenant or use, aging equipment, changes in local codes, increasing indoor air quality, or reducing energy costs by increasing energy efficiency.

Engineered Air Balance (EAB) performs commissioning services for commercial new construction and remodel projects on a regular basis. However, customers occasionally request EAB’s commissioning services for an existing facility. Typically, the primary goal is to evaluate that facility’s current operating state, and to uncover any necessary changes needed to meet the Current Facility Requirements (CFR).

A need for EBCx

As facilities age, building systems inherently degrade or fail. Additionally, building requirements change with new tenants or uses. For these reasons, among others, the need for Cx services may arise. Once a facility owner or a governing authority having jurisdiction (AHJ) determines there is a need for EBCx, the facility owner will assemble the CFR and EBCx scope and find a qualified commissioning provider (CxP). To paraphrase the ASHRAE standard describing EBCx, the commissioning process is as follows. The CxP team will Assess the documents provided by the owner, Investigate the facility using onsite observations and measurements, suggest changes to Implement, and Hand-off the gathered information to the facility owner.


EAB commissioning team assessment

During the assessment phase, the CxP team will analyze and organize the information provided by the facility owner. This information will be used to create an EBCx Plan and to generate benchmarks which aid in data collection during the Investigation phase. Additional data will also be collected during the assessment phase, including utility data, energy costs, maintenance schedules, an occupant survey, and equipment specifications. The EBCx plan is a roadmap for the remainder of the project.

The EBCx Plan will include all project information provided by the owner and data collected and analyzed during the assessment phase. Additionally, the EBCx Plan will include contact information and communication protocols, roles and responsibilities of EBCx team members, a schedule and procedures for all activities, and a Training Plan for the Hand-off phase. Once the EBCx Plan is completed and approved, the Investigation phase begins.


The intention of the Investigation phase is to determine how closely the existing equipment, in its current operating state, meets CFR criteria provided by the owner. The CxP team will make observations and perform tests to evaluate the existing equipment using the procedures and benchmarks determined during the Assessment phase. The owner’s team is expected to provide support for these activities as detailed in the EBCx Plan, including facilitating any recommended minor adjustments and modifications. Often, low-cost and no-cost repairs are performed by the O&M team or respective trades, during this phase. Examples include sensor calibration, minor BAS changes, or any small repairs that fit within the O&M annual budget. The CxP team will document all results in an investigation report provided to the owner at the culmination of this phase.

The investigation report will contain a list of all adjustments and minor modifications made, a list of all deficiencies found, and a prioritized list of recommended system repairs and upgrades. The report should serve as a guide to assist the owner in determining the best allocation of resources to achieve the CFR in the Implementation phase.


CxA doing EBCx implementation

The implementation phase is an extension of the Investigation Phase. While minor, low-cost and no-cost repairs are typically completed during the Investigation Phase, more capital-intensive repairs are completed during the Implementation phase. The owner will use the investigation report, provided at the culmination of the Investigation phase, to prioritize, schedule, and facilitate the completion of repairs or upgrades that were not previously completed. These types of changes demand a significant amount of time to complete due to the approval, research, scheduling, and construction time required. For this reason, the Implementation phase is separated from the investigation phase. The CxP team is typically not on site during the majority of the Implementation Phase. Upon completion of all scheduled updates, the CxP team will return to reevaluate all building systems affected by the scope of the Implementation phase. Once the evaluation is complete, the CxP team will prepare for the Hand-off phase.


The Hand-off phase is the period where information, collected by the CxP team, during all previous phases, is provided to the owner’s O&M team. Much of the information is provided in the form of a Systems Manual which contains a record of the final state of the facility within the scope of the EBCx activities. Information contained within the Systems Manual includes all setpoints and sequences of operation, benchmarking procedures, and lessons learned. The Systems Manual serves as a foundation for the CxP team to train the O&M staff in the operation of systems affected by the EBCx scope. Training normally happens upon completion of all Cx verification activities. Additionally, the O&M staff is trained to use and update the Systems Manual so that it may be a living document for future reference.


Retro-commissioning and Re-Commissioning services can uncover the hidden potential of an existing facility and provide a roadmap for building owners to adapt to changing building requirements. Whether facility requirements change, or the goal is simply to increase energy efficiency, achieve better indoor air quality, or lower operating costs, EAB’s commissioning team is well equipped, and eager to provide unmatched commissioning services for any project.

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