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Commissioning: Introduction

Commissioning is a concept currently in the process of being formally defined. Numerous industry groups have published and/or are in the course of publishing their interpretation of what commissioning is and how it should be implemented. These groups include SMACNA (Ref. 1), Bonneville Power Association (Ref. 2), and ASHRAE (Ref. 3).

The article is intended to be a rudimentary introduction to the concept of commissioning. There is no “right” answer to the fundamental questions about commissioning, i.e., what, why, when, how, and who, but we will start to explore some of the issues associated with the process. Following this article I will be writing a monthly column for Engineered Systems which will delve more deeply into each of these questions and follow the progress of the industry as it attempts to define and justify this “new” idea.

This article is biased towards HVAC system commissioning, the most common type of commissioning performed to date, because that is my personal area of expertise. However, the concepts and implementation approaches presented here are equally applicable to electrical, fire protection, life safety, and/or whole building commissioning.

What is Commissioning?

There are about as many definitions of commissioning as there are projects which might need to be commissioned and as there are people who are interested in providing commissioning services. The following is a comprehensive, though generic, definition.

Commissioning is a systematic process of assuring by verification and documentation, from the design phase to a minimum of one year after construction, that all building facility systems perform interactively in accordance with the design documentation and intent, and in accordance with the owner’s operational needs, including preparation of operation personnel.

Why is Commissioning Needed?

Commissioning is needed for various reasons, but most facility owners who advocate commissioning will tell you it’s because new buildings simply do not work when construction is complete. What an owner considers important for a “working” building varies depending on that owner’s priorities, but the following are some areas which have proven to be especially troublesome:

  • More Complex and Powerful Systems

  • Indoor Air Quality

  • Energy Efficiency

  • Safety

  • Accreditation Requirements

When is Commissioning Performed?

Although, in practice, commissioning can be started at any time during a building project, the following are three typical scenarios, the first of which is considered ideal for achieving the most success from the commissioning process.

Design through Occupancy Commissioning

The commissioning process which begins early in the design phase of a project and extends into occupancy of a new facility is the industry’s ideal scenario. A commissioning consultant (CC) is brought onto the design team at the same time the project’s goals and objectives are being developed.

The CC serves as the owner’s technical liaison throughout the design, construction, and startup phases. In this capacity it is the CC’s responsibility to keep communication open between the owner and the design team and to help interpret the owner’s wishes in light of the technical requirements of the project. The CC is the “keeper of the gate” when it comes to reviewing the design engineers’ plans for compliance with the owner’s intent. The CC also makes sure that the design is “commissionable” in the sense that components necessary for meaningful verification testing, e.g., temperature and pressure gauges, flow meters, control system interfaces, etc., are included in the design.

Post-Construction Commissioning

Although design-through-occupancy commissioning is an ideal, the post-construction mode of commissioning has until recently been the most prevalent. A specialist in system analysis, testing, and commissioning (the CC) is brought into a construction project typically following substantial completion when the owner realizes there are problems with the installed systems and looks for help.

The role of the CC in this scenario varies considerably from the design-through-construction scenario, because the CC is most often an outsider who was not involved in the design, construction, or the problems and politics inherent to both. The CC may walk into a delicate situation where design and construction team members have been attempting to resolve the apparent system problems with little or no success. They may not be interested in having an outside “know-it-all” enter the process. Therefore, conciliatory and professional interpersonal skills are extremely important qualities for the CC.

As part of post-construction commissioning, the CC will learn about, evaluate, test, and document the installed building systems. Often the CC will also be closely involved in operator training as a part of or following the testing procedures.

Existing Building Commissioning (Recommissioning)

Recommissioning existing building systems of any age can reduce energy consumption, improve indoor air quality, and improve temperature and relative humidity control. In addition, it is an opportunity to analyze the air and water system balance within a building and optimize distribution system performance. In a building in which multiple architectural renovations have taken place over a period of time, recommissioning offers an opportunity to re-evaluate the mechanical and electrical systems in light of the new building arrangements, aspects of “small” renovations which are often ignored during their implementation.

How is Commissioning Performed?

Regardless of the mode of commissioning undertaken, the following tasks can be part of the CC’s responsibility:

  • Help develop and define owner’s design criteria.

  • Evaluate design for conformance to criteria.

  • Develop, perform, and document verification tests.

  • Prepare system documentation.

  • Prepare final report.

  • Prepare preventive maintenance plans.

  • Oversee and conduct operator training.

There are three key components of the commissioning process. The process will not succeed if any one of the following is missing:

  • Design Intent Documentation

  • Verification Testing

  • Operator Training

The following is a step-by-step example of one way commissioning can be implemented in a design and construction project. The actual scope of commissioning and the level of detail undertaken typically depends heavily on the owner’s budget and priorities.

Design Phase Tasks

  • The design intent document is most typically prepared by the designers, but they may need input as to what a design intent document should include from the CC.

  • The CC will perform periodic design drawing and specification progress reviews to verify compliance with the design intent document and to confirm clarity and commissionability of the systems being design.

  • Preparation of the Commissioning specification section (CSI has assigned Section No. 01810 for this purpose) for the contract documents. This is a section which details the commissioning process for the bidding contractors and their responsibilities in that process. The CC will also coordinate with the designers’ technical specification sections to ensure that appropriate references are made to the commissioning section and that adequate definition of documentation, testing, and training requirements are included for each system being commissioned.

  • Preparation of draft verification test procedures for inclusion in the commissioning specification. These test procedures define exactly what steps are to be taken in testing the systems at the end of construction and what the acceptable results will be. It isn’t fair to “surprise” the contractor with undocumented requirements at the end of the project, so clearly defining what will be expected is critical to winning the cooperation of the installation contractors.

Construction Phase Tasks

  • The CC will review key equipment submittals in parallel with the design engineers’ review, to ensure that commissioning-related aspects of the documentation are included and well defined. This is particularly important for automatic temperature control system shop drawings.

  • Following final acceptance of the equipment by the design engineers, the CC will prepare final verification test procedures tailored specifically to the equipment and systems being installed.

  • The CC will prepare system “readiness” checklists to be completed prior to the start of verification testing. These will document that all of the prerequisites of system operation are in place and complete, e.g., for an air handling unit this could include electricity to the fans, steam and chilled water to the coils, air and water balancing work complete, clean filters, calibrated sensors, etc.

  • During construction the CC will conduct commissioning planning meetings to communicate and emphasize the importance of the commissioning process, to review test procedures, and to incorporate commissioning related tasks into the master construction schedule.

Verification Testing

  • The CC will conduct/witness the performance of the verification test procedures. The contractors associated with each system being tested will be present for all testing.

  • The CC will document the tests, including all system parameters, setpoints, occupancy schedules, etc. The documentation process will also include issuing corrective action reports for each deficiency found and following up on the corrections by retesting any systems/components which failed the first test. 

Training

  • The CC will oversee the training specified to be provided by the contractors, documenting training plans, attendance, and videotaping, if desired.

  • In addition to the equipment-specific training typically provided by the contractors, the CC will conduct “system” training to communicate the design intent and the way all of the individual components are to function together as a system. System operators can’t be expected to maintain continued proper operation of a commissioned system if they don’t know how it’s intended to perform and why. New technologies and control strategies need to be explained and justified so that building operators will “buy into” the new system.

  • Whenever possible, operations and maintenance staff are encourage to participate in and/or witness the verification tests as an excellent source of hands-on training.

Documentation

  • Operations and maintenance manuals are taken very seriously for commissioned systems. In addition to enforcing the specified O&M documentation requirements, the CC may prepare “enhanced” system manuals which would include the design intent document; balancing report; detailed system schematics and control strategies; points lists with initial setpoints; zone/system database; and/or zone floor plans.

  • The final commissioning report includes a narrative of the commissioning process as applied to that particular project; the design intent document; blank verification test procedures and system readiness checklists for future use; documentation of actual meeting notes, test reports, corrective action reports, and other correspondence.

Who Performs Commissioning?

It seems as if everyone wants to perform commissioning, and it’s possible that each group is appropriate for commissioning certain types of projects. This paper is not intended to be a proponent of any one group over another. The following is a list of people who could perform commissioning:

  • Installation Contractor

  • Balancing Contractor

  • Construction Manager

  • Design Engineer

  • Third Party Commissioning Consultant

  • Owner

Cost of Commissioning

Because commissioning is still in the process of being defined and standardized, nailing down a cost for commissioning is especially challenging. A rule of thumb to use is 2-4% of the construction cost of the systems being commissioned. Some of the factors impacting the cost of commissioning a particular project include:

  • When commissioning starts

  • Number of systems commissioned

  • Complexity of systems

  • Tools available

  • Level of detail required

  • Allocation of costs

  • Size of facility

Benefits of Commissioning

The following is a summary of some of the major benefits of commissioning from a building owner’s perspective:

  • Commissioning eases the transition from construction-to-occupancy.

  • In general, a building whose HVAC systems have been commissioned will have better environmental control, i.e., temperature, humidity, and pressurization control, than buildings which are not commissioned.

  • Similarly, the indoor air quality in commissioned buildings is likely to be better than in non-commissioned buildings, due to the verification of proper outside air intake and filtering controls.

  • The energy savings realized as a result of commissioning are very real but difficult to quantify, because all construction projects are unique and it is impossible to reliably predict the quality of the control systems without commissioning. Experience has shown, however, that there are numerous energy conservation-related anomalies found during verification testing that may never have been corrected without the commissioning process. Without commissioning, therefore, the owner may have paid higher energy costs throughout the life of the facility.

  • The operator training portion of commissioning helps to ensure the persistence of good environmental conditions and energy savings in the future. Inadequately trained operators will be more likely to make changes and/or adjustments which could result in the discontinuation of the initial benefits of commissioning.

In conclusion, commissioning is an old concept which has become a significant undertaking with the advent of complex, inter-related building systems and the relatively recent emphasis on energy conservation and indoor air quality. There are many ways to implement a commissioning program for various levels and types of building projects, many of which could benefit from commissioning. As the industry continues to gather and consolidate data from individuals and groups performing commissioning, more information will be available to make a quantitative case for the benefits of commissioning.

References

  1. SMACNA. 1994. HVAC Systems Commissioning Manual. Chantilly, Virginia: SMACNA.

  2. Bonneville Power Administration. 1992. Building Commissioning Guidelines. Portland, Oregon: Portland Energy Conservation, Inc.

  3. ASHRAE. 1989. Guideline for Commissioning HVAC Systems. Atlanta, Georgia: ASHRAE.

 

Commissioning: Getting It Right

Engineered Systems, January, 1998

by
Rebecca Ellis, PE, LEED AP, CCP, CxA
President
Questions & Solutions Engineering
1079 Falls Curve
Chaska, MN  55318
rteesmag@QSEng.com