Commissioning: Nice Building -- How's It Work?
Last month’s column focused on efficiently communicating equipment and device locations to the future O&M staff during new system installation. With the O&M staff familiar with the location of all major and minor components well before substantial completion, end-of-construction training can concentrate on how all of these components function together as systems.
System training is one of the most important aspects of a successful commissioning process. Without it, even a perfectly installed and optimally operating system at the end of construction is likely to degrade over the first few months of operation. Today’s building systems are too complex, integrated, and computer-based for their intended operation to be “obvious” to the people required to operate them after the contractors leave.
The What's And Wherefore's Of System TrainingWhereas equipment O&M training is about individual pieces of equipment and their maintenance, system training focuses on communicating the following information to the O&M staff.
Operating parameters. What are the systems designed to do? What are they not designed to do? Possible factors include: heating and cooling mode space temperatures and humidities; outside air design conditions; building pressure relationships; IAQ; equipment redundancy; backup power; load assumptions (lighting loads, people densities, computer loads, etc.); etc. Without this basic information, O&M staff may be influenced or tempted to tweak systems to deliver conditions they are unable to provide.
Basis of design. System training should include an opportunity for the design engineers to present and explain their system design. Recognizing that there are many ways to achieve the same operating parameters, the design engineers can explain why they chose the approach they did.
Schematic diagram. System training should include a detailed graphic depicting each component in a system and its relationship to other components. For a central heating hot water system, this might include the heat exchanger, pumps, expansion tank, and air separator. It will also include control valves and all sensors used to monitor and/or control the system. For air or water HVAC systems, the components are shown connected to each other by either pipes or ducts. After training, it should be possible for the O&M staff to take the schematic diagram into the building and find all the components by physically tracing the pipes and/or ducts between them.
It is critical that the relative position of the various components be accurate. For example, in an air-handling system schematic: Is the freezestat located upstream or downstream of the heating coil? Is the high static cutout switch located upstream or downstream of the smoke isolation damper? Is the discharge air temperature sensor upstream of downstream of the supply fan?
Riser diagram. Where applicable, system riser diagrams should be shared during system training. These are typically building cross sections that show the locations of major system components (fans, pumps, AHUs, etc.) and the locations of their duct and pipe riser mains extending through the building.
Sequence of operation. The control strategies for all modes of operation need to be covered in detail. These include any differences in seasonal operation and setpoints as well as the various occupied, unoccupied, economizer, non-economizer, emergency, etc., modes of operation.
Interfaces with other systems. After reviewing all of the above individual system-specific information, system training should also present and explain all of the interactions required and programmed between systems. For example, an air-handling system and the fire alarm system typically communicate regarding the status of smoke detectors and the status of the main fire alarm system. System training should detail which system initiates each communication and what response is required from the receiving system.
These topics need to be covered for each new or modified system in a facility. Typically, system training is delivered in multiple sessions organized into logical system types. For example, the air systems (air-handling systems, makeup air systems, exhaust fans, etc.) may be covered in a single system training session. The hydronic systems, steam systems, electrical power systems, etc., may also be combined into their own system training sessions.
Because systems are, by nature, the product of multiple parties (designers, manufacturers, installers, control programmers, TAB contractors, commissioning professionals, etc.), the training should be delivered by a team of instructors. The planning and coordination of the team, however, needs to be assigned to a single party. I believe the designers or commissioning professionals are the best choices for this planning role, as they are the team members who should have the broadest view of the systems as a whole. ES