Tips and tricks for commissioning, balancing buildings
CSE: What tips can you offer engineers working on commissioning projects?
Feyler: During the design phase, a meeting should be held for the commissioning engineer and the design engineer to review the systems chosen and the sequences of operations, plus a controls integration meeting to share experiences on similar systems and the results from previous projects with similar systems and building types for the systems being included within the design. During the submittal phase, on complicated projects, it is beneficial for the design engineer, CxA, and controls contractor to meet prior to the final approval of the control scheme to ensure that all are in agreement on the control mythologies and sequences. During the construction phase, after the control submittal is approved, the commissioning engineer drafts the functional testing documents. Sharing the draft functional testing documents with the design team and contractors for their review and input will ensure that prior to the release of the final testing documentation, all parties have reviewed and provided input on the documents, and all parties have a though understanding of the design intent. A beneficial procedure our team has incorporated into the commissioning specification is for the contractors to “dry run” the system prior to commissioning. This requires the contractors to test the systems using the functional performance tests, to debug and check programming and operation. RDK requires a sign-off of the dry run prior to site commissioning. All of the above ensure that the contractor has a full understanding of the system operation prior to commissioning.
Bauers: Effective execution of any field testing effort is almost entirely dependent on preparation prior to arrival at a project site. While a test procedure can be a long, complex process, its component parts should be quite simple and clear. Each step in a test procedure should be specifically designed to demonstrate an element of performance clearly and without confusion. And the purpose of that step (or series of related steps) should be clear to the execution team. In the end, testing is only valuable if it either demonstrates success or points clearly to corrective actions that lead to success. Preparation prior to going to the field, understanding the systems to be tested, the objectives of each step of the test, and strategies to deal with the unexpected are essential to effective field execution.
Wolff: There are a number of tips:
- Break it down into manageable steps; you can’t eat an elephant in one bite.
- Take the time to review and play devil’s advocate with the sequence of operation. Make sure that the sequence covers all aspects of operation including what happens during a loss of power and return to normal power after an emergency (often ignored). And, if an engineer is going to “borrow” a sequence from a previous (similar) project, take the time to go through the sequence and make sure all the changes are made to make this one applicable to the project (often ignored).
- Have the installers pretest the systems before you attempt to “commission” them. There is no greater waste of time than organizing a test and getting everyone out to the site and in place only to find out the contractor running the test is not ready, the system is not ready, or the contractors don’t understand their role and responsibility.
- Change the way people view “functional testing.” It should not be viewed as “well, let’s flip the switch as see what happens.” Functional testing should be viewed as “functional demonstration.” We are not testing to see if it works, but rather demonstrating that it works in accordance with the designer’s expectations and the owner’s project requirements.
- Start from the basic concept of “How does it (the piece of equipment/system) turn on and turn off?” If you can’t prove those basic functions, then the rest is meaningless.
- Test from the approved as-programmed sequence of operation, not the engineer’s operating “intent.” The intent is usually vague and is not detailed enough to create a test from.
- Ensure there is time in the schedule for BAS provider and engineer to review the test scripts and provide comments weeks before the test is executed. You might find how you are planning to test the system can’t be done, or that the sequence used to create the test is out of date and no longer applicable.
- Be flexible; know the test procedure you spent all that time on will have to be modified in the field while performing the test.
York: The best tip for engineers working on commissioning projects is to become proactively involved early with the owner and design team and remain involved with both throughout the project. The CxA is there to assist the design team professionals and as such can help designers avoid problematic and costly errors that would otherwise be discovered during construction or occupancy. Early designer involvement helps the CxA better understand the design intent, and together the CxA and design team can incorporate the devices and sequences needed to successfully test and validate the systems operation. Continued involvement and communication with designers during construction and commissioning helps the project team make minor adjustments to system performance as well as helps the designers further their professional development.
Linder: A few tips we press upon our staff include:
- Do your homework; understand the owner’s functional requirements that were to be met.
- There is no substitute for getting dirty on a project; don’t just sit at the direct digital control (DDC) front end observing operations.
- Develop detailed testing procedures and don’t skip steps.
- Validate functionality and DDC reporting of all components before you test equipment; don’t just trust the controls contractor.
- Functional verification is not complete until all integrated systems testing is finished and conformance to the design intent was observed and documented.
Szel: Understanding the sequence of operation is key. Review the operations and maintenance (O&M) manuals for information on how the equipment operates. If the sequences don’t make sense, don’t be shy about making that phone call to the engineer of record. If it still doesn’t make sense, engage the vendor’s technical group. I recently went to a factory witness test at a major chiller vendor. We had some very detailed technical questions. The vendor brought in its lead installation technician to speak with us. He was a great resource. It is important to remind the team that the end goal of commissioning is to hand over a quality, operational building to the owner.