Miles Ryan, a P.E. at QSEng co-authored this ASHRAE published article about his experience in The U.S. Air Force.

An engineer who is as comfortable in the field as they are in the office is someone you want on your team, especially if your team operates and maintains facilities. Developing this competence can take years of experience, but appropriately focused training early in one’s career can provide junior engineers an extremely valuable head start. This is especially critical in the U.S. Air Force due to the high-turnover nature of our personnel system and the typical project procurement methods implemented. Engineers in the Air Force operate and maintain over 47,000 facilities across the globe and field competence is critical to ensure the effective and efficient operation of all those building systems. With these facilities spread across 183 locations, providing service-wide professional development is particularly challenging. Many readers are, in some capacity, involved in providing HVAC education. The intent of this article is to demonstrate some of the innovated techniques use at the Air Force Institute of Technology’s Civil Engineer School to kick start that path toward field competence.

 

The Students

The professional community within the Air Force entrusted to maintain and operate its facilities are the Civil Engineers. They consist of both military and civilian personnel, and at times are augmented by contractors embedded within a base’s Civil Engineer Squadron. Military engineers are quite mobile, typically moving to a new duty location every few years. Military engineers’ frequent moves are intended to develop their breadth of experience, to prepare them to someday lead a squadron or even a larger unit. While civilian engineers do not move as frequently as their military counterparts, many often depart after a few years of experience for the private sector or government positions in more desirable locations. Of those civilians that make the Air Force a career, the high performers often rise quickly through the ranks into more managerial positions. The combination of these factors creates a revolving door of talent where the engineers relied on the most typically have less than four years of experience.

 

Despite their limited experience, these junior engineers are given significant responsibility. They often oversee several simultaneous projects totaling millions of dollars. They help define the owner’s project requirements and ensure those requirements are adhered to through the often-outsourced design process. They will be the continuity bridge between design and construction, as design-bid-build is still the standard project delivery method for large facility sustainment, restoration, and modernization projects. It is these junior engineers who provide the contracting officer the technical review and approval/rejection recommendation on construction submittals, as the Air Force rarely pays for such services from the engineer-of-record. They will be the liaison between the construction and occupancy phases of a project, since it is their squadron who acquires the responsibility of operation and maintaining the facility after the project ends. Placing this much responsibility on such junior engineers is, admittedly, not a recipe for guaranteed success. Therefore, it is vital these engineers are given all the tools available to foster their development and ensure their success.

 

The Program

The Civil Engineer School’s mission is to support the Civil Engineers operating air bases throughout the world. Over 75 different continuing education courses are taught to over 10,000 students each year on a wide range of topics. The remainder of this article will discuss the suite of courses that provide HVAC education.

 

Possibly the greatest obstacle in reaching students is that they reside at air bases across the globe. Tightening budgets limit the amount of opportunities to fly students to the school to attend in-residence courses. Thus, a shift to more distance learning course delivery methods has occurred in recent years. Table 1 shows the current course offering in the mechanical program. The only in-residence course is WENG 561: Applications of HVAC Design and Analysis. The remaining courses are distance learning, which use a variety of technologies to improve their effectiveness. Several of those technologies are detailed in the article.

WENG 460, WENG 563 and portions of WENG 560 have their content delivered through pre-recorded, on-demand lessons. This provides flexibility to the instructors who are balancing other teaching and consulting commitments, deployments and instructor turnover (teaching assignments for military instructors are typically only three years in duration). It also frees up instructors’ time for more impactful interactions with students, whether through phone calls, online discussion boards or live help sessions. However, there are challenges to these pre-recorded lessons, primarily in keeping the content up-to-date.

Though the science governing mechanical systems doesn’t change, Unified Facilities Criteria (UFC) documents, the codes and standards those UFCs reference, and Air Force policies are constantly changing. Thus, recent shifts in the online platforms used for lesson delivery primarily have been to allow for real-time changes to the content. If it is realized half-way through the course that a lesson contains out-of-date information, the platforms now used allow for instructors to make edits and push updates to the versions being viewed by students in a matter of minutes. For example, the Air Force prohibition on variable refrigerant flow systems in January 2017 came right in the middle of an offering of WENG 563, which has a lesson on the technology1. Instructors were able to quickly make edits and ensure all students received the most current guidance governing the use of that technology. Previously, the editing process was so laborious it was often pushed off until the end of the course offering (i.e., after all the students received incorrect information). The streamlined editing process has further freed up instructors for more valuable interactions with the students.

Another major undertaking in recent years has been automating the grading process for these distance learning courses. One criticism of this approach is it limits the instructor’s ability to assess how well the students are comprehending the material. For example, short answer test questions provide greater insight into student comprehension of a topic that multiple choice questions. However, automated grading provides instructors substantially more time for teacher-to-student interactions, and we find such interactions to actually be more effective in gauging student comprehension.

Students experience increased instructor interaction in a variety of ways. First, each distance learning course offering has its own online discussion forum. Pre-canned questions are posed to students daily (another fully automated process) to get a feel for their level of understanding of the material they have been exposed to. The ensuing conversations not only allow for teacher-to-student learning, but student-to-student learning and networking as well.

Second, live help sessions are incorporated into these courses through several delivery methods. Virtual conferencing, which allows for two-way audio and visual (i.e., screen sharing), has been an effective platform to revisit some of the more difficult concepts discussed in the pre-recorded lessons. Help sessions are also delivered through live broadcasts from one of the Civil Engineer School’s two broadcast studios (Photo 1). These broadcasts can be streamed via satellite (effective for students in austere locations with limits internet connectivity) or directly to individual students’ desktops. Depending on the streaming method the students choose, they can ask live questions audibly or through text. The green screens are compatible with many additional technologies, such as the virtual mechanical room models discussed later in this article, to help improve student comprehension. A team of broadcasting professional is present to assist the instructors in maximizing the effectiveness of the technologies incorporated.

 

Mechanical Room Familiarization

One theme carried throughout the three more advanced courses is building student confidence in navigating a mechanical room. Entering such a space can be intimidating for junior engineers, especially if they don’t have a mentor on site to assist. We strive for our students to gain confidence in the field and to be hands-on with the systems they are entrusted to maintain. Gaining this familiarity is deemed so important that it cannot afford to be put off until the single residence course we offer, WENG 561. Hence, a variety of technologies are used to incorporate mechanical room familiarity into the distance learning course offerings as well.

We start by embedding videos from within mechanical rooms into the on-demand lessons in WENG 563: HVAC Control Systems and WENG 560: Fundamentals of HVAC Design and Analysis. Like most HVAC education, there are a lot of schematics used in presenting the lesson material, but supplemental videos showing what those schematic components physically look like has been extremely valuable. For example, WENG 560’s lesson on primary equipment has embedded videos distinguishing between air-cooled and water-cooled chillers, and how these are connected to the larger HVAC system. More nuance discussions are supported by these embedded videos as well. Such an example comes from one of the more advanced lessons in WENG 563 on Low ΔT Syndrome. The lesson discusses the common mistakes of piping-in coils in a parallel-flow arrangement as opposed to the more effective counter-flow arrangement2. That statement alone may trip students up, so it is supplemented with some schematics (Figure 1) followed by an embedded video showing a correctly piped-in cooling coil next to an incorrectly piped-in preheat coil on the same air-handling unit (AHU) (Photo 2).

Many of the lessons in HVAC Control Systems discuss common sequences of operation for HVAC systems at length, and we like to show students how to quickly identify when system deficiences (either through incorrect installation or operation) are degrading system performance. It is difficult to find a mechanical room readily available with all the deficiencies being discussed to improve student comprehension. The Air Force Institute of Technology (AFIT) uses 3D computer models of various mechanical rooms and equipment for just that purpose (Figure 2)3. These models are editable and provide instructors the flexibility to input select deficiencies when needed to supplement a given lesson.

Since facility mechanical systems typically span the entire facility’s footprint, we needed a technology to effectively show distance-learning students how to go about locating the components of a mechanical system throughout a facility and gain a better understanding of how such systems are configured. To do this, AFIT purchased a 3D camera that allows for the creation of self-guided, virtual reality models of building mechanical systems (Photo 3) This technology is often seen in real estate industry. Students access these models online, where they work through various mechanical spaces that have been captured to gain familiarization. Embedded text boxes located on various devices within the virtual spaces, allow students to read more about what they are seeing.

Similarly, videos can be embedded within the models as well, allowing instructors to join the students at select pieces of equipment to provide more thorough explanations. The models contain hot spots, which allow student to navigate through a wall or ceiling where piping or duct penetrations exist. Students are then transported to the location the piping or duct is headed. Through use of this feature, one homework assignment in WENG 560 requires students to trace, and then sketch a schematic of an entire chilled water system for a 54,000 ft2  (5017 m2) facility). Working through this real-world task in a non-threatening, virtual platform forces students to apply their education rather than passively absorb it.

 

Mechanical room familiarization is further expanded when students arrive on campus for WENG 561. Previous instructors, during the design of our school house in the early 1990s, had the foresight to locate the mechanical classroom adjacent to a mechanical room. Large windows in the wall separating the spaces and the ease of access between them allow for a didactic experience by making the mechanical room an extension of the classroom (Photo 4).

 

Students are taken on numerous tours throughout the many mechanical spaces across campus during the week-long WENG 561 course. Most tours are guided, but students are provided opportunities to explore for themselves. Several of the mechanical spaces have been outfitted with numerous placards to make these self-guided tours more effective.

 

Applications Based Learning

The historical complaint from students about the continued teaching our design courses (WENg 560 and 561) is that we rarely perform in-house designs in the Air Force. The common rebuttal from instructors has been that part of an Air Force mechanical engineer’s job is to evaluate designs completed by others, and the process of effective evaluation exhibits a higher level of learning that what it takes to design4. To appease student concerns however, some adjustments have been made in recent years. The courses are titled “design and analysis”, thus the course has shifted greater emphasis to the analyzing of HVAC systems. The principles used for both design and analysis of these systems are the same. Accordingly, we structure our lessons to teach the principles with design examples, followed by student application of those principles through an analysis exercise. For example, in WENG 561 several lessons are dedicated to the design of a single-duct variable air volume (VAV) reheat systems. One lesson walks through the selection process for a VAV box with hydronic reheat coil. As stated before, students would rarely perform such a task. Accordingly, the follow-on in-class exercise has students perform a submittal review exercise in which they are provided several submittal packages, are required to navigate provided design documents and then articulate their reasoning for approving or denying the package. As mentioned earlier, recommendation for submittal approval/rejection is well within their responsibilities.

 

This application-based learning is incorporated elsewhere. Here are several notable examples from WENG 561 that have been received well by students.

  1. One lesson discusses the concept of pump curves, system curves, and operating points. After a review of these concepts, students are given the opportunity to experiment with a pump trainer. The trainer consists of a constant speed pump serving a single loop piping system with a calibrated balancing valve and a manual ball valve that can be used to throttle the pump. The students take differential pressure readings across the pump and estimate flow from the pump curve. They then compare that to an estimate generated from measuring differential pressure across the calibrated balancing valve. They can adjust the position of the ball valve to throttle the pump to gain a better understanding of changing system curves and the concept of “riding the pump curve.”
  2. The lesson which discusses air system balancing is followed by students assembling an airflow capture hood, taking airflow measurements across the classroom’s diffusers, and comparing those values to as-builts of the space.
  3. The lesson on air-side economizers discusses the concept of damper and chilled water valve sequencing, as well as economizer high limits. The students are then allowed to see this economizer sequencing and disabling living, through the use of a building automation trainer. The trainer represents an AHU with an actual modulating damper actuator and chilled water valve, along with other devices, all controlled by a programmable digital controller (Photo 5). The trainer allows for students to adjust variables such as outdoor air temperature and discharge air temperature setpoint to see how the AHU responds.
  4. The students are taught how to leverage building automation systems (BAS) to more effectively troubleshoot their systems, a practice underutilized in the Air Force. Students are first given a tour of the Industrial Control Shop on Wright-Patterson Air Force Base, which monitors and controls over 240 buildings across the base. The students are then given in-class exercises where they are provided scenarios accompanied by screen shots of the BAS graphics for an AHU and VAV box serving the space in question. They are required to determine the root causes of the performance issues. Homework for that evening consists of students sifting through trend log data to identify system deficiencies that cannot be discerned in real time, such as sequence of operation insufficiencies, which result in frequent freeze stat trips. The homework also exposes students to potential pitfalls in trending, such as aliasing5. They are provided trend data for an unstable chilled water control valve at different trend intervals to see how inappropriate trending intervals can mask what is really occurring in the system.

 

Conclusion

Due to the great responsibility junior engineers in the Air Force are often given, effective training early in their careers is essential for their success. Developing their field competence has been the focus in recent adjustments to the mechanical curriculum at AFIT’s Civil Engineer School. This article sought to detail how AFIT has leverage technologies readily available to both capture and sustain these engineers’ interest in facility mechanical systems.

 

References

  1. Department of Defense. 2017. UFC 3-410-01: Heating, Ventilating and Air Conditioning Systems, Change 3.
  2. Taylor, S. 2002. “Degrading Chilled Water Plant Delta-T: Causes and Mitigation.” ASHRAE Transactions 108(1).
  3. Sellers, D. Facility Dynamics Engineering. SketchUp Models. http://www.av8rdas.com/.
  4. Bloom, B., M. Englehart, E. Furst, W. Hill, D. Krathwohl. 1956 Taxonomy of Educational Objectives: The Classification of Educational Goals. Handbook I: Cognitive Domain. London: Longmans, Green and Co.
  5. Sellers, D. 2003. “Installation of Data Loggers: ‘Aliasing’ and other pre-installation considerations.” HAPC Engineering (1):88-90.
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