Building commissioning challenges, solutions: Automation and controls
Commissioning, recommissioning, or retro-commissioning, can be a challenge—and the more complex a facility is, the more boxes an engineer has to check to get the job done right. Building automation systems, sequence of operations, and controls are of key importance.
- Ray Dodd, PE, CxA, LEED AP , President, Total Building Commissioning Inc., Phoenix
- Kyle G. Hendricks, LEED AP, Energy and sustainability consultant, Environmental Systems Design Inc., Chicago
- Donald H. Horkey, PE, LEED AP, Principal, mechanical engineer, DLR Group, Minneapolis
- David J. LeBlanc, PE, FSFPE, Senior vice president, Rolf Jensen & Associates, Inc., Framingham, Mass.
CSE: What factors do you need to take into account when commissioning and integrating automation and controls systems?
LeBlanc: As it relates to commissioning fire and life safety systems and integrating automation and control systems, one of the critical factors we run into is whether the systems are UL listed to perform their intended function. For example, all smoke control equipment and controls per the International Building Code (IBC) are required to be UL 864 listed. The systems and their components not only have to function in their field, but they also need to meet specific listings to be part of the fire and life safety systems.
Dodd: Not all equipment manufacturers build their equipment with the same communication protocols. Many building management systems are specified to be BACnet while items like generators employ a modbus protocol for mapping points. This is an item often missed in the submittals that commissioning can resolve. Once we begin functional testing, systems integration can be a challenge because despite what is written in the sequence of operations for each piece of equipment, the systems (a group of equipment operating together to serve a function) may dynamically interact in a way that was not expected or intended. Our role is to facilitate the solution with the team (controls, design engineer, owner).
Horkey: The trend in the industry to open protocol control systems and increasing level of system complexity has significantly changed in the last 5 years. This level of complexity has required commissioning professionals to have a deeper understanding of system architecture and associated interfaces to various communication protocols. As more equipment is coming from manufacturers with factory-installed controls and sequence of operations, communication of these subsystems is becoming extremely important. Commissioning professionals need to spend a great deal of time ensuring that the integration of multiple systems is working as designed in addition to the normal prefunctional and functional testing of the system.
CSE: What aspect of the building automation system (BAS) is most overlooked when initially designed? What solutions have you offered clients when commissioning the BAS?
Hendricks: Definitely the sequence of operations. Many design firms prefer to specify the controls, or even just the mechanical, electrical, and plumbing (MEP) systems, and leave the controls design and sequences up to the contractor. Our firm has a dedicated team of controls and automation experts who are able to provide consulting on energy-efficient and robust controls strategies. On many projects, we have provided clients with improved sequence of operations as part of the standard commissioning process.
Horkey: It sounds simple, but it’s important to understand that all other equipment installation needs to be complete to have a fully completed BAS, so delays on final completion of a BAS are almost expected. You often need to start with only a portion of systems fully installed, working alongside the controls contractor to complete commissioning in a timely manner. As more open protocol systems are designed and installed, control system manufacturers still tend to try to minimize how interoperable their systems truly are. Just because systems are BACNet or LonWorks based doesn’t necessarily mean that they will be fully operable. Commissioning professionals can provide tremendous value to building owners during construction documentation review and submittal reviews to ensure that control manufacturers are providing the level of system interoperability that the owner is expecting.
LeBlanc: The most overlooked item for BAS when commissioning fire protection and life safety systems is that all smoke control equipment needs to be UUKL listed and be tested against UL Standard 864. This requirement is an IBC requirement, a listing requirement, and a requirement in order to provide the reliability and redundancy needed for fire protection and life safety systems.
Dodd: Coordination between mechanical and electrical engineers. Also trend requirements, scheduling requirements, setpoints, and modes of operation are poorly defined. We facilitate solutions by reviewing the design documents knowing by experience where coordination can fall short. We also have some example BAS specifications of what works well and provide samples for engineers to use as a reference.
CSE: Describe a sequence of operations challenge you solved in a building automation/control system.
Dodd: We were involved in a 26-story high-rise project where the designer divided the control of the air-handling systems into two sides based on loads. The building management system (BMS) contractor didn’t understand the intent of the design and tied the two systems together to solve air pressurization issues. Part of the air pressurization issues was caused by the fact that the building was in a core-and-shell state and there was a wind tunnel up the elevator shafts. Part of the solution was understanding the dynamic changes that would occur when the high-rise was built out. We worked with them on segregating the pressure sensors correctly so after build-out they could separate the pressure measurements allowing the building to operate as designed.
Horkey: We tend to see lots of challenges with outdoor air, return air, relief air, and supply air measurements. It is very difficult for design engineers to always specify airflow measurement locations in the system to facilitate highly accurate measurements. These measurement errors can cause significant operational problems if they are used in control subroutines for building pressurization or fan speed control. When we see these potential issues in sequence of operations, we recommend modifications to the system be implemented to directly measure and control via direct measurement of the parameters desired, that is, measure space pressure and use that measurement to control damper position and return fan speed.