Underperforming facilities, which do not meet the user's needs, waste valuable resources. These resources include land, capital, building materials, labor, and energy. They also reduce occupant satisfaction and productivity, further compounding the negative impact. New building commissioning, done properly, eliminates the deficiencies responsible for insufficient facility performance. However, when facilities have not been sufficiently commissioned or have not been commissioned at all, the resulting deficiencies are discovered time and time again during retro-commissioning.
Retro-commissioning is the systematic process which ensures an existing building and systems are optimized to perform interactively to meet current operational needs as closely as possible. Retro-commissioning is most often used to correct or optimize the performance of an underperforming facility. The process differs from commissioning in that it includes the investigative phases at the beginning of the process. The commissioning agent investigates the existing building operation, condition, and capability, in addition to determining the original operation and capability. Retro-commissioning also differs from new construction commissioning in that the commissioning agent is responsible for performing all the commissioning tasks.
While performing retro-commissioning, we have discovered and corrected thousands of deficiencies. Nearly all the problems can be traced to seven fundamental causes, which are:
These are the seven fundamental root causes of building operational problems. Not all of these issues apply to every project, and some projects will exhibit more or less issues than others. In order to allow the reader to better understand these causes, each will be explained in detail.
Fundamental Cause #1: Designers and users did not communicate the “why” of the basis of design. In other words, the designers indicated what facility conditions needed to be achieved, but the “why” or reasoning involved in reaching those conditions was not documented. During development of the owner's project requirements and the design team's basis of design documentation, all parties must be explicit about facility requirements and why those requirements are necessary. When the “why” is not adequately documented, the basis of the performance requirements can be misinterpreted, misunderstood, forgotten, or never communicated to key team members. These key personnel include the design production staff, subsequent or substitute designers, facility users, and most importantly, operators. Without understanding the original design team's “why,” subsequent changes to the sequences of operation and systems performance prevent the facility from meeting that “why.”
Example: The design team has established that we need N+1 redundancy on our exhaust and supply air systems. Why? Is it because the use of the laboratory requires the minimization, to the point of elimination, of any possible hiccup in our directional airflow for containment? Or, is it because we have long term laboratory activities planned in which a short duration shut-down isolation of the laboratory is acceptable but, long-term we need to maintain acceptable environmental conditions? These two “whys” result in drastically different operational criteria.
Fundamental Cause #2: Designers knew conceptually how they wanted the building systems to operate, but did not provide the detailed operational sequences to make it happen. Most sequences of operation indicate, in general, how the systems are supposed to perform in normal operating modes. Most do not detail exactly what each component should do and when. This is especially true during staging, transitional, and emergency operation. Very detailed sequences need to be developed and provided as part of the construction documents. When the detail is not provided, the contractor fills in the blanks based upon his or her previous experience, lowest cost, or personal preference.
Example: In a laboratory building with standby generators with priority load add/shed requirements, the designer specified very short (five-second) durations between the priority load add/shed groups. This was done in an effort to get critical systems back online first, but the designer did not provide the detail on how to accomplish the requirement. The contractor used their standard building automation system (BAS) architecture to implement the system, which did not work due to unpredictable time delays in the BAS communication network. The BAS system did not recognize a power failure in a timely manner, nor initiate the stop and run commands in any predictable or repeatable manor. This resulted in cycling equipment power on/off, sometimes as many as four times during a single transfer to generator, due to slow BAS response and equipment interlocks.
Fundamental Cause #3: Value engineering decisions were not made by the right people or for the right reasons, preventing the owner's requirements from being met. Value engineering can be a very beneficial process. However, all team members who originally established the facility operational requirements must be involved. This helps ensure the cost reductions do not prevent the building systems from achieving their intended requirements. The owner must be made fully aware of, and agree to, the impact on his or her requirements. If the value engineering decision results in any performance reduction, that reduction needs to be analyzed and a determination made as to the resulting impact on facility usage. In addition, that performance reduction must be well documented and made available to all team members.
Example: A three-story laboratory facility with over 200 terminal air valves connected to a single manifolded exhaust system. During the design process, control dampers were added at each floor so that individual floor differential pressure setpoints could be established. With the selected terminal air valves, a differential pressure needs to be maintained across the valve of 0.3” to 3.0'' of w.c. A single setpoint would not satisfy all 200 valves. The dampers were removed from the project during the value engineering process by individuals that thought the dampers were a “luxury” as opposed to a necessity. The dampers and associated controls were later installed—at a substantially higher cost—so that the system would work.
Fundamental Cause #4: Systems were never sufficiently tested to ensure proper operation, resulting in a legacy of inefficiency and occupant dissatisfaction. Functional performance testing, the heart of the commissioning process, provides the owner with the assurance that his or her facility operates correctly. The contractor's QA/QC process does not provide sufficient assurance testing, is primarily focused on only installation, and seldom includes the operational aspects of facilities. The functional performance test procedures must be developed specifically for the project. Non-specific “canned” procedures will not provide the depth and rigor required for today's building systems. The procedures must test all aspects of system operation with the depth and rigor required to provide the proper level of assurance, including laboratory module and integrated systems testing. Because of the complexities of today's building systems, the commissioning tasks, from test development to performing and directing the testing, should be performed by independent, discipline specific commissioning experts.
Example: Most testing programs address the integrated building systems response to a power outage. The standard testing approach is to simulate a single sustained utility outage lasting several minutes. However, in real life, this is not typically how power outages occur. Statistics show that most utility power disturbances are short events, due in part by utilities reconfiguring transmission breakers to restore service or initiate one or more breaker reclosures every few seconds in an attempt to “clear” a fault. These short, possibly repetitive outages affect building mechanical and control systems much differently than a prolonged outage. The testing needs to simulate the various “real life” scenarios and verify correct building response to each.
Fundamental Cause #5: Testing, adjusting, and balancing (TAB) was neither properly performed nor verified, leading to incorrect and inefficient building operation. Correct procedures along with accurate airflow and hydronic measurement and adjustment are critical to ensure safe and efficient operation of the facility. Proper pressure relationships, necessary for laboratory operation, must be accurately set and verified through the full range of design capacities. The TAB procedures must be detailed to ensure proper results and correct setpoints, resulting in the most efficient operation. These procedures should be reviewed by the commissioning agent to ensure they will meet the objectives. Effective TAB verification requires more than simply reviewing the TAB report and limited “spot checking.” Actual verification of airflow and hydronic flow quantities needs to be performed on all critical systems and components.
Example: A TAB contractor left the default minimum airflows in the office VAV terminal devices. The values were too low to provide proper transfer air quantities to the laboratory corridors. The minimum flow rates were never verified. When the office was in a minimum air mode, the directional airflow was insufficient to maintain directional airflow to the laboratory corridors, resulting in compromised containment.
Fundamental Cause #6: The facility users were not trained on the building systems' operations and limitations. When laboratorians move into a new, state-of–the-art facility, they often believe the systems will meet all their needs and wants, all of the time. Providing the users with detailed knowledge of actual systems operation, responses to various scenarios and limitations is necessary to providing an optimal work environment. Providing this knowledge will assist the owner's with developing appropriate laboratory procedures and, more importantly, provide the users with the knowledge of why those procedures exist.
Example: Users do not fully understand the impact of adjusting snorkel iris dampers or slide valves on the airflow volumetric offset, and hence containment, for the laboratories. Depending on system configuration, adjusting the exhaust volume for snorkels can make a laboratory become positive. Another item often encountered is that laboratorians seem to assume that all the laboratory and support equipment, including the HVAC systems, is on uninterruptible power supplies. They need to be informed of how the laboratory support systems are configured and exactly how the systems respond to certain real life operating scenarios.
Fundamental Cause #7: Operations and maintenance (O&M) staff were not sufficiently trained, have not had hands-on experience operating the systems, and do not know the “why” of that operation. Often the O&M staff does not fully understand the detailed system sequences or how the systems are designed to meet the users' needs. Including the O&M staff in the commissioning process allows them to operate the systems through all modes and witness the intended sequences prior to the facility “going live.” This provides an understanding of the operating characteristics and the system anomalies. Proper training provides the staff with the designer's intent, the actual systems' intended operation and the users' needs. If the O&M staff is not equipped with this information, they do not have the necessary knowledge to provide proper systems operation and maintenance.
Example: At a laboratory facility, the control system required operators to manually reset alarms through the building automation system user interface. The system had them initiate a reset function, but also required them to turn off that reset function. The operators didn't understand this, the system stayed in “alarm reset” mode, and the equipment problem continued with no alarms registering. The redundant equipment and system eventually failed.
Throughout the project delivery process, the project team needs to be
aware of and initiate measures to address these seven fundamental causes
of problems. This will assist the team in reaching their ultimate project
goal: providing a facility that meets the users' needs.
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Patrick Prendergast serves as the Project Manager/Commissioning Authority for many of GBA/ViroCon's commissioning projects. As the commissioning authority he has over nine years of experience providing formal commissioning services. Projects include laboratories, zero down-time facilities, and large governmental facilities. Pat led the on-site commissioning activities for CDC's building 103 and CDC's building 18. Pat has been a speaker and provided educational commissioning workshops at the Labs21 2006 Annual Conference, CDC's 6th annual bio-safety symposium, the American Biological Safety Association (ABSA) 2005 international conference, National Association of State Facility Managers (NASFA), National Environmental Balancing Bureau (NEBB) and others.
James Whorton serves as the Project Manager/Commissioning Authority for many of GBA/ViroCon's retro-commissioning projects. As the commissioning authority he has over 17 years of experience managing the on-site activities of the commissioning team, and providing formal commissioning services. Projects include laboratories, zero down-time facilities, and large governmental facilities. Jim led the on-site commissioning activities for CDC's building 110. Jim is an expert in diagnosing and correcting problematic building systems. He currently sits on the National Environmental Balancing Bureau (NEBB) Retro-Commissioning Procedural standards committee. This committee has developed the NEBB procedural standards for retro-commissioning of existing building systems.