Getting Into Gear
CTG Energetics Inc. (CTG) was retained by TMS as a third-party commissioning agent to ensure that HVAC and lighting systems were installed and are operating as designed. In addition to the traditional commissioning activities of functional testing and identifying and resolving deficiencies, LEED (see sidebar) required that design and submittal reviews were performed throughout design and construction.
Major pieces of mechanical equipment commissioned included seven natural gas-fired space heating hot water heaters, six direct-fired gas absorption chillers, four variable-speed cooling towers, constant and variable-speed pumps, constant and variable-volume AHUs, exhaust fans, and control sequences designed to minimize building energy use.
As an additional level of redundancy beyond spare chiller capacity, the primary chilled water loops of the two central plants are interconnected so that chilled water can be diverted from one plant to the other if necessary. During normal operations, Central Plant A serves Building A and Central Plant B serves Building B. The interconnection allows Central Plant A to provide chilled water to Building B and vice versa.
Electrical systems were also evaluated. Lighting was the primary electrical system commissioned. Components included control panels and their programming, manual override switches, occupancy sensors, and photocells. Illumination measurements were also taken in order to ensure that design illumination levels were being achieved.
As a result of TMS's Inc.'s commitment to the concept and practice of building commissioning, the process began in the design development stage, well in advance of construction. This resulted in buy-in and active participation from stakeholders (design engineers and contractors as well as TMS facility staff). This cooperative effort enabled the team to remain focused on the ultimate goal of providing a facility that would meet the needs of the occupants for the lowest initial and operating costs - especially during the "crunch times" that inevitably occur at the end of any construction project. Absence of any one of these elements would have compromised the commissioning effort and increased construction time and project cost.
This article describes some of the key reasons for the success of the project, and attempts to distill a number of lessons learned that could be applied to other projects.
TMS was Committed to CommissioningAt the start of the project, TMS was eager to investigate the commissioning process and potential benefits. Adhering to their corporate philosophy of Kaizen, in which improvement is a continual process, TMS was committed to improving their construction practices. To that end, TMS requested that CTG provide a presentation and question and answer session so they could learn more about commissioning and how it could enhance the South Campus project.
This information, combined with their own cost/benefit analysis, encouraged TMS to pursue commissioning as a cost-effective approach to meeting the needs of the occupants and operators. "The initial goals of the project were all about efficiency and reducing operating costs," said Brian Conner, national project development manager, TMS, "The byproduct of meeting these business objectives was a facility with significant environmental benefit. The commissioning process is an integral part of guaranteeing that this benefit was achieved."
Once committed, TMS embraced commissioning and remained actively involved in the process throughout the project, including attending weekly meetings that began over a year before the estimated construction completion date. By establishing commissioning as a key metric of success early in the process, TMS emphasized its importance.
When times got tough and deadlines were in jeopardy, rather than asking how the commissioning process could be shortened, TMS asked what they could do as the owner to help the team achieve the original goals. The option of cutting corners, in spite of looming deadlines, was never offered as an alternative. TMS's unwillingness to compromise was instrumental in not settling for "close enough."
Commissioning Started EarlyOften misconstrued as a task that occurs at the end of construction, commissioning provides greater benefits when integrated into the initial stages of a project. Past experience, contractor feedback, and operator preferences can be communicated to the engineers for incorporation into the design. Changes proposed in the later phases of design (or even during construction) are frequently too expensive or too disruptive to be incorporated.
Incorporating changes early leads to a smoother, more cost-effective implementation. For example, sequences of operation and workstation graphics can easily be changed during the design phase, but can result in costly change orders if modified after programming has been completed.
Commissioning was included as a standing agenda item at each of the weekly South Campus MEP coordination meetings. As the construction neared completion, the meetings transitioned into commissioning meetings with MEP issues as an agenda item. Involving the design and construction team from the beginning enabled them to view CTG as part of the team, and not a late entry outsider.
During these meetings the commissioning agent offered opinions about the potentially challenging parts of the project from the commissioning perspective based on past experience. Achieving the rated cooling capacity and efficiency (COP) of the absorption chillers was identified early as a potential issue. As a result, TMS included chiller performance testing and acceptance criteria in the project specifications. Consequently, these conditions were stipulated in the purchase order with the chiller manufacturer.
This layer of protection proved significant during the course of functional testing when it became apparent that the chillers could not produce the specified capacity. Rather than bickering over the appropriate course of action, the team had a mechanism in place to deal with the then potential, now real issue. Based on the ARI 560-2000 Standard, Absorption Water Chilling And Water Heating Packages, CTG developed with input from the manufacturer, a testing procedure for measuring the performance of the machines.
Further testing demonstrated the machines were producing less capacity than tolerances allowed. Actual cooling capacity ranged between 84% and 91% of design. As a result, CTG is currently working with the chiller manufacturer to determine the cause of the shortfalls, and define the appropriate course of action.
In addition to providing input throughout construction, the commissioning agent worked to ensure that commissioning activities were integrated into the project schedule from the earliest phases. Although construction schedules change, accounting for the time required for commissioning activities and making it clear which team members will be involved with each task enables subcontractors to recognize that it is not an overnight process. Advance planning allows the team to better achieve goals when working against an aggressive schedule. This was particularly important since TMS was aiming to be LEED-certified by Earth Day 2003. With dates defined and an understanding of the required effort, adjusting the work schedule to longer days and some weekends made it possible to complete the commissioning process on time.
Cooperation from All Project StakeholdersAlthough the commissioning agent manages the process, it is very much a team endeavor and cannot succeed without cooperation and effort from all parties. The team included TMS, the design engineers, and the contractors.
As a result of the strong commitment demonstrated by TMS and the early introduction of commissioning as an essential part of the project, team members bought into the concept and became active participants. "Teamwork is a strong value in our culture at Toyota," explained Conner. "We have discovered that the environmental initiatives and, in particular, the commissioning process helped develop a stronger, more cohesive team. We found the process something that we [development, operations, and contractors] could all rally around and become more unified in our approach to getting the issues resolved."
Based on CTG's experience with large-scale commissioning projects for a variety of building types, this level of teamwork and collaboration is rare. Often, the relationship between the commissioning agent and the design and construction team is adversarial, when ideally the agent should serve as a resource provided by the owner to facilitate design and construction whenever possible.
Unfortunately, commissioning agents are sometimes regarded as justifying their existence by creating needless extra work for the construction team. According to Jett McCormick, project manager, Turner Construction Company, "A key element to the success of the commissioning process of the South Campus project was teamwork," further adding, "It truly was a team effort." McCormick also noted that inclusion of detailed commissioning requirements in the bid documents ensured that everybody understood what would be expected of them.
LEED Energy and Atmosphere Credit 3 states that additional commissioning requires design reviews at both the design document and construction document phases. It is not uncommon for engineers to interpret these reviews as being told how to do their jobs. Although some ideas generated through the review process were integrated into the South Campus project and others were not, the design engineer was always willing to consider suggestions.
"The success of this project was realized by involving the commissioning agent during the design development phase and continuing this involvement through value engineering, submittal review, and construction," according to David S. Mitchell, project engineer, Glumac International. "When both the engineer and commissioning agent see the design and construction process as a collaborative effort, obstacles that arise in phases of project development are far more easily overcome. This ultimately benefits the owner and keeps the project on course."
A Team Effort, Especially During ‘Crunch Time'From the onset, the South Campus schedule was aggressive. As with any construction effort, delays that invariably occur over the course of construction catch up with the team as the project nears completion. Although prepared to delay the dedication ceremony if necessary, Toyota wanted to schedule the ceremony and presentation of the LEED plaque to coincide with Earth Day on April 22, 2003. As completion deadlines came down to the wire, everybody knew what had to be done to make the project successful. The final critical piece of the puzzle was the completion of the commissioning. Everybody rolled up their sleeves and got the job done.
ConclusionOwner support for the commissioning process is critical to a successful commissioning project. If the owner does not buy into the process, then neither will the design team, general contractor, or their subs, and without their cooperation, the commissioning agent is rendered ineffectual and the process destined to breakdown. Beginning early allows relationships between the commissioning agent and the rest of the team to develop over the course of the project and build an atmosphere of teamwork. Issues can be addressed in the conceptual phase, before they have been transformed into reality and costly to change. Making the initial investment in the commissioning process is repaid several times over. ES
Team-Based Approach Identifies Return Fan Capacity Shortage ProblemA key element to the performance of VAV AHUs is the ability of return fan to volumetrically track the supply fan. In the course of evaluating (functional testing) the fan-tracking algorithm, it was revealed that the return fans could not provide their design airflow. Below is a short narrative as to how the tracking was evaluated and the problem identified.
Using the BAS, the supply fan static pressure algorithm was manually overridden, the fan speed was locked at 70%, the economizer (return and exhaust air dampers) was put into full return mode, and the outside air dampers were closed. The volumetric fan tracking offset was then set to zero flow and the tracking of the return fan was observed coming into stable control at setpoint with the flow indicated at the BAS, as well as the pressure and flow transmitter display, to be the same as the supply fan.
The access door to the mixed air plenum was opened and released to swing freely (if the door opens, the return fan is leading the supply fan, if the door closes the supply fan is leading the return fan, and if it remains neutral the flows are equal). Although not utilizing a lot of whiz-bang gadgetry, this method proved very successful in evaluating the ability for return fans to track volumetrically. Once the tracking was adjusted for higher flows, the supply fan speed was reduced to 30% and the process was repeated to ensure proper tracking throughout the range of operation.
As an integral component of fan tracking, the air monitoring stations and transmitters were also evaluated for accuracy. We began by comparing the installation with the manufacturer's recommendations, and it appeared to be in accordance with these recommendations. The next step was to measure the supply fan inlet diameter in order to verify that the programmed area factor was correct. Based on the measurement, and the area formula (π x r2) multiplied by 2 (double inlet fan), the area factor was correct.
After verifying the installation and programming, a NIST-certified ADM was placed into the pneumatic lines upstream from the Veltron II pressure and flow transmitter to measure the velocity pressure. Manual calculations using the area factor and the velocity pressures confirmed that the cfm displayed by both the BAS and pressure and flow transmitter was correct. Our conclusion that the actual return fan capacity was short of design contradicted the air balance report that indicated the return fan capacity to be near design.
Further investigation revealed fundamental flaws in the air balance methodology. After initial measurements indicating that the return flow was short of design, the balancer "helped" the return fan. The economizer was put into the full return position, the outside air dampers was fully closed, and the supply fan was operated at full speed in order to "suck" the air through the return fan.
Representatives from across the team were taken to a typical unit in order to demonstrate the problem firsthand. Eventually, the team acknowledged the issue and evaluated solutions. Providing a larger motor and new VSD was evaluated, however, the cost far outweighed the number of hours when the return fan would have operated at 100% capacity. Eventually, the return fan VSDs were adjusted to operate slightly above 60 Hz, pushing the motors into the service factor in order to get the maximum fan capacity possible. After the adjustment, the system performed closer to the design targets.
- Fan inlet measurement - measured;
- Area factor - calculated; and
- Velocity pressure (in wc) - NIST-certified ADM.
- Air velocity (fpm) - 4,005 x √ velocity pressure;
- Calculated air volume (cfm) - air velocity x area factor; and
- % Error - (veltron-observed volume - calculated volume) / calculated volume.
The LEED™ Green Building Rating SystemDeveloped by the USGBC membership, the Leadership in Energy and Environmental Design (LEED™) Green Building Rating System is a national consensus-based, market-driven building rating system designed to accelerate the development and implementation of green building practices.
In short, it is a leading-edge system for designing, constructing, and certifying the world's greenest and best buildings. The full program offers training workshops, professional accreditation, resource support, and third-party certification of building performance.
The current version of the rating system, LEED 2.0, was launched in March 2000 following review by the entire USGBC membership and a national pilot testing program. LEED 2.0 is designed for rating new and existing commercial, institutional, and high-rise residential buildings; however, active member committees are developing criteria addressing new project types. For more information, visit www.usgbc.org.