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Melissa Dowland, North Carolina Museum of Natural Sciences

Commissioning Pitfalls and How to Avoid Them

Oct. 1, 2010
Avoiding these errors will help lower costs and make the commissioning process more useful to the design/bid/build team.

Recently, I collaborated with the Urban Green Council—the New York chapter of the U.S. Green Building Council (USGBC)—on a list of commissioning (Cx) pitfalls for urban commercial and institutional projects seeking Leadership in Energy and Environmental Design (LEED) certification. Avoiding these errors will help lower costs and make the Cx process more useful to the design/bid/build team:

Problem: An owner sends out a request for proposals (RFP) that includes every system in the building as part of the Cx scope. When the proposed Cx fees come back double (or more) what was anticipated, the owner is forced to trim the Cx scope to an acceptable level. A new proposal then must be prepared, which causes delay and additional labor expense.
Solution: Focus the RFP, rather than create it through a "blank-check" brainstorming process. Commission only the systems providing real benefits. Do not duplicate code-required inspections also required and confirmed by governing agencies. The LEED-certification Cx process can be 80-percent less expensive when security systems, emergency generators, uninterrupted-power-supply systems, etc. are not included. Structure the Cx process to fit needs appropriately.

Problem: An owner wants to send out an RFP for Cx services that is accurate and complete, but does not know where to start.
Solution: The value of the Cx process will be greatly enhanced if a staff member takes formal Cx training. When the owner chooses a representative to oversee the project, he or she should require proof of formal Cx training and some degree of certification. Only after training and certification can a staff member buy wisely.

Problem: A project manager waits until the end of the design stage to develop the owner’s project requirements (OPR). He or she then discovers that several aspects of the design do not fit the OPR, requiring a costly and error-prone redesign.
Solution: Hire a Cx authority (CxA) early in the project (prior to schematic design), as required for LEED certification. Develop the OPR as a team mission statement, and adhere to it throughout design. The OPR then becomes a useful tool to compare and record ideas instead of a paperwork exercise. It does not cost more to bring a CxA on early; it actually costs less.

Problem: A design team waits until the 100-percent construction-document (CD) stage to send plans and specifications to a CxA for a LEED-certification design review. When the CxA returns a long list of items that are not consistent with the OPR, the design team is forced to either miss the deadline or provide a design that does not meet the owner's expectations.
Solution: Conduct the design review before the 50-percent CD stage, as required for LEED certification. This provides time for discussion if disagreements arise. Beginning a design review early allows sufficient time for an OPR to be changed, if needed. Reviewing plans at the 100-percent design-development stage provides more time, but the specifications may not have been started yet, and details may not be sufficient.

Problem: Instead of supplying equipment listed in CDs, a contractor makes substitutions. If the CxA is not notified and arrives at the site with the wrong test forms, the project is delayed, causing budget issues.
Solution: As contractors' equipment submittals are approved, send copies of Cx paperwork to the CxA. If equipment is substituted at any time during the construction process, send the CxA the revised and approved equipment submittals. This is the general contractor's/construction manager's responsibility.

Problem: System sequences of operation are unclear or incomplete in bid documents. Installing contractors then must make guesses in the field. This creates misunderstandings among operations-and-maintenance staff members and conflicts among interconnected equipment. As a result, energy-saving, health, and comfort strategies no longer work as planned.
Solution: Bring the CxA into the job during the planning process before schematic design, as recommended in the USGBC's LEED for New Construction Version 2.2 Reference Guide. The owner's OPR and the engineer's basis of design (BOD) should be checked by the CxA. Later, the CxA should check plans and specifications against the OPR and BOD to confirm they are complete and correct. Make it clear to the design team that the project will be commissioned and they must be specific about sequences.

Problem: The design team plans to earn LEED Indoor Environmental Quality Credit 3.2, Construction IAQ Management Plan Before Occupancy, by flushing out the air in the building. When construction ends, there is not enough time for the lengthy flushout procedure, and the point is lost.
Solution: The design team should calculate the time required for the flush when plans and specifications are submitted for review. The design team also should discuss the impact of the occupancy delay vs. the cost of indoor-air-quality testing, which usually can be completed in a few hours (typically $1,000 to $2,000).

Problem: When systems are commissioned at the end of a project, existing equipment, such as boilers, chillers, and cooling towers, does not communicate with the new building-management system. The result is either a costly change order or a lack of control and monitoring. Lack of control and monitoring results in increased energy bills for the life of the building.
Solution: Use the OPR and BOD to describe interactions between new and existing equipment in detail. These documents are checked by the owner and the CxA, confirming what the owner wants and needs to operate an efficient building. The Cx process then ensures that the OPR and BOD are reflected in the bid documents. The equipment submittal confirms the equipment ordered, the actual control architecture, and the final programming.

Problem: A CxA arrives on site expecting systems to be ready for testing, but the installing contractors have not been informed. As a result, the systems may be running without being completely connected to controls. Therefore, the systems are not ready for testing, resulting in increased CxA fees and delays in system verification.
Solution: Broad Cx milestones should be added to the general contractor's/construction manager's overall schedule when the CxA is brought on board at the beginning of the project (prior to schematic design). As the time for fieldwork approaches, these timelines should be examined in greater detail. When the verification is a few days/weeks away, the CxA should prepare upcoming schedules to be distributed and enforced by the general contractor/construction manager.

Problem: When a building is complete, it is pressurized with warm air and scanned with infrared equipment. If the air barrier in a soffit is not correctly installed, infrared scanning will reveal the inevitable leaks. At this point, there is neither time nor money left to fix the problem, so either a costly court battle will ensue or the owner will pay increased energy bills for the life of the building.
Solution: A wall mock-up should be built so the design team can inspect and verify the air-barrier details. As soon as the first part of the actual building is completed, it can be tented and tested via pressurization. Any problems can be corrected before the remaining 90 percent of the building is completed.

Do these sound familiar? It is hoped that understanding history will prevent us from repeating it. If you have experienced problems like these and/or have alternate ways of heading them off, please leave a comment below.

A commissioning project manager for AKF Group LLC, a full-service engineering firm, Ron Wilkinson, PE, LEED AP, is an authority on commissioning Leadership in Energy and Environmental Design (LEED) Green Building Rating System projects and sustainable buildings. He is the author of the first commissioning training program for LEED for New Construction and Major Renovations. He is a longtime member of HPAC Engineering’s Editorial Advisory Board.

About the Author


The founding principal of Seattle-based Wilkinson Commissioning Management, Ron Wilkinson, PE, LEED AP, CPMP, is the author of the first commissioning training program for the Leadership in Energy and Environmental Design (LEED) for New Construction and Major Renovations Green Building Rating System and the founding recording secretary for ASHRAE Guideline Project Committee 0.2/1.2, The Commissioning Process for Existing Building Systems and Assemblies/The Commissioning Process for Existing HVAC&R Systems. An ASHRAE Distinguished Lecturer and an American Institute of Architects Continuing Education Lecturer, he has spoken on commissioning practices internationally. He is a longtime member of HPAC Engineering’s Editorial Advisory Board.