Purpose and Approach
Learn HVAC is an interactive tool designed to introduce fundamental HVAC concepts to students. The concepts of HVAC operations come alive by the presentation of real-time 3D animations of the detailed, accurate simulation of a simple HVAC system. The real-time animated simulations permit the user to observe the dynamic performance of HVAC control systems responding to the changing HVAC system and its components. Users can view the HVAC system operating normally, or with one or more "faults" activated.
Students can move through the 3D animation/simulation, viewing each system component as it operates. These components visually change according to user inputs and in response to second-by-second simulation calculations. The user can view 3D animations of air and water movement plus performance data.
Functionality and Features
3D Animation and Conversion to Web GL
The current version of Learn HVAC uses a 3D animation engine developed in Flash ActionScript 3.0. The user can observe realistic animations of how the HVAC system and its components are operating. The animations do require a certain level of processing power (an average desktop or laptop purchased in the last few years is usually fine). Learn HVAC has the option, however, to scale back or turn off the animations to accommodate earlier machines. A popup "performance" dialog box allows the user to modify several system performance parameters.
An important part of Learn HVAC is that a user can view the HVAC system either operating normally or operating with one or more "faults" that cause the system to operate outside of normal conditions. Many faults can be activated to varying degrees, using "sliders." Often the HVAC system or component being impacted by a fault can adjust to the fault with little or no symptoms or negative impact until some threshold condition has been crossed. A variety of faults have been implemented already, with many more planned to be made available for user activation in the future.
When a scenario is started, the user can interact with the animated simulations in one of 3 basic ways:
- View normal operation: The user can observe the system behaving normally, with no faults activated. The software parameters can be set to ensure that no faults are inadvertently activated. Thus, a user can be comfortable that the operation being viewed is indeed "normal" for the season, time, occupancy conditions, and other initial settings.
- Activate known faults: The user can activate one or more known faults to mild or severe levels and can observe their impacts on system behavior. This is an excellent educational-use mode.
- Troubleshoot a scenario with unknown faults: An instructor can create scenarios with single or multiple faults that are hidden from the user; the challenge to the student is to find the faults and propose corrective action. Instructors will often group students into teams to do the troubleshooting. Such problem-based case study (PBCS) scenarios can range from being simple and quickly solvable to difficult and complicated, requiring a team a week or more to solve.
Short- and Long-Term Use Case
In addition to Learn HVAC's real-time animated simulator described above, which provides close-up snapshots of dynamic system behavior in the short term, users are also able to obtain longer-term results, such as monthly or annual performance summaries. The long-term analysis is provided by one or more simulations using EnergyPlus. This type of energy-impact scenario operates as follows:
- When a scenario is created, an EnergyPlus annual simulation runs key building features that correspond to the conditions of the scenario. The EnergyPlus zone loads for the initial time of the scenario, generating input loads for the short-term animated simulation. The EnergyPlus input file and selected outputs (I-O files) are saved with the scenario by Learn HVAC.
- When a user selects and activates an energy-related scenario, the EnergyPlus I-O file is copied to the user's directory.
- The user can modify the real-time, short-term inputs and faults, as before.
- Utilizing the new, energy-related variables, the user can now make changes to impact energy use, peak demand, and HVAC operations.
- The user can also request a second long-term comparison EnergyPlus simulation. This will use the basic I-O of the first simulation, but will incorporate the changes made by the user in the short-term animated simulation.
- The user can compare the original and revised EnergyPlus results as well as the original and revised simulations.
Users are still free to use just the original use case with the short-term 3D animated simulation and no energy analysis.
Storage and retrieval of user I-O data
A key objective in this current version is to allow a user to compare the energy efficiency of a current set of HVAC conditions to a previous (initial) set of conditions. In order to allow such comparisons, this version of Learn HVAC allows students to store and to retrieve at least a limited set of user data. The current version, when completed, is expected to allow one comparison per user, per scenario.
Data Structures for 5-zone analysis
The future version of Learn HVAC is being designed with a data structure to permit examination of any one of 5 zones (North, East, South, West, Core) on the chosen floor (top, medium, or ground) of a building. This allows users to switch from zone to zone in analyzing HVAC system performance. For example, HVAC behavior at 3 pm on a sunny summer afternoon can be expected to vary considerably by zone.
EnergyPlus within Learn HVAC
A user of Learn HVAC can easily activate comparative annual EnergyPlus simulations. Our EnergyPlus implementation is currently limited toward specific education objectives. We use a large office prototype file, developed at LBL for the US Department of Energy (DOE). Learn HVAC also expands upon a user front end to EnergyPlus that was developed by LBL as part of a demand-response application. This results in an easy-to-use Graphic User Interface (GUI) front-end that allows a user of Learn HVAC to specify key building features of interest. The user can quickly select:
- Climate location (and its associated weather file).
- Building configuration, orientation, and key window features.
- Key internal loads by zone.
All other building inputs are defaulted, using the rules imbedded in the prototype macros. When ready, the user clicks a button to run EnergyPlus.
Comparative charting of results
Results variables from EnergyPlus and programmed simulations can be selected and charted using "drag and drop" techniques. Currently, charts can be either time series or XY. In developing this capability, the Learn HVAC software team is making use of techniques developed under another collaborative effort with LBL for CEC. That effort produced a proof-of-concept prototype of visualization concepts—see www.viztool.org.
E- Leaning Approach
Learn HVAC uses goal-oriented, problem-based case study methods to find solutions to complex system-level equipment problems. It promotes a team approach to problem solving and encourages communications and interactions within and between teams and course instructors.
The primary intended users of this first version of Learn HVAC are students and instructors in 2-year technical degree HVAC and ECT programs in community colleges. Within future potential versions of Learn HVAC, we may also be able to address the needs of other types of users with different needs for software-based analysis, presentation, and interaction. Other possible users may include:
- Building operators
- Engineers focused on the operation, commissioning, retrofitting, and retro-commissioning of building HVAC systems.
- Students in 2- or 4-year universities with technical HVAC programs or schools of architecture
- High school students
- Participants in union apprentice programs
HVAC systems and controls in buildings are becoming increasingly complex, digitized, and difficult to properly design, construct, operate, maintain, and troubleshoot. Building operators and technicians today must master new computer-based technologies in addition to their traditional skills.
Several major trends are increasing the complexity and difficulty of properly operating and maintaining buildings:
- Digital control technology is becoming pervasive on both new and existing buildings. Thus, building operators and technicians must master a new set of computer-related skills (e.g., hardware, software, database management, and local-area networking) in addition to their traditional skills of HVAC management and repair.
- Regulations and policies are increasingly involved, including new commissioning and sustainability factors.
- Energy performance monitoring, commissioning, and retrocommissioning address increasing energy costs, but require advanced capabilities to be effective.
- Security is increasingly important since 9/11 and operators must monitor advanced security systems, initiate emergency response plans, and shut down complex systems in the event of environmental attacks.
As building industry professionals strive to keep up with these increasing needs, one result is that many buildings are not operating properly, thus providing marginal or poor comfort and quality while using much more energy than needed. In many cases, actual energy savings in buildings with advanced technological capabilities falls far short of potential savings, due to the demand for advanced training for building-operations professionals outpacing supply.
Meeting the Need
Saving energy in buildings involves more than just new energy-efficient gadgets and technologies. High-efficiency equipment that is not properly installed, calibrated, tested, operated, or maintained will likely save far less energy than anticipated. Creating a truly energy-efficient building industry involves training skilled people to design, construct, operate, and maintain its increasingly complex buildings and systems.
Learn HVAC addresses this need through the creation of more accessible, engaging problem-based learning software for use in 2-year technical degree HVAC and ECT programs in community colleges. Learn HVAC focuses on teaching system-level troubleshooting skills as well as business skills in communications and teamwork.