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Industry highlights Oct 15, 2022

Insight: Integrated Fault Detection and Diagnostics FlexTiles


Daniel J. Boorstin, historian at the University of Chicago, said the greatest obstacle to discovery is not ignorance; it’s the illusion of knowledge. It’s not what we don’t know that stands in our way; it’s the misperception of what we think we know.

Mechanical systems, sequences of operation, and automation systems grow steadily more complex. It’s common to speak of the intelligence or intellect of facilities and systems. Building operators now have hundreds, thousands, or millions of data points in their automation systems. We might assume these expanding volumes of data automatically grant intelligence or knowledge, but raw data alone is essentially useless. Knowledge is not a commodity that can be bought and sold. The staggering volume of information can impede insight and understanding. The conversion of raw data into meaningful information empowers an organization to understand and act, building knowledge.

Mechanical equipment and systems routinely fail to satisfy design performance criteria or operate according to the tuning performed during commissioning. Significant equipment faults or catastrophic system failures are hard to ignore for facility maintenance teams, but minor operational faults and poor performance are easier to ignore and can go unnoticed indefinitely. The detrimental effects of poor performance accumulate over time, are predictive of equipment failure, and result in a significant increase in operating and resource costs. It’s estimated that 5 percent to 30 percent of the energy used in commercial buildings is wasted due to mechanical faults and control errors.

A report presented at the 2013 Australian Summer Study on Energy Efficiency and Decentralised Energy Conference estimated that detection and remediation faults in mechanical systems could result in energy savings of 17 percent.

report prepared for the California Energy Commission estimated that of the 28 percent of electricity consumed by HVAC in commercial facilities, at least 10 percent is wasted due to poor performance. Proactively detecting and resolving poor performance of HVAC equipment and systems could save 5 percent to 30 percent of facility energy use.

study by the New Buildings Institute for the Northwest Power and Conservation Council surveyed 503 rooftop units in 181 commercial facilities and found comparable opportunities for energy conservation. These included faults in cooling performance (46 percent of the units), economizer operation (64 percent of the units), improper airflow (42 percent of the units), control errors (58 percent of the units), and failed or faulty sensors (20 percent of the units). The study estimated that detection and resolution of these faults could reduce energy consumption by up to 40 percent.



Quickly identifying and resolving poor performance from equipment faults or control errors is fundamental to ensuring energy-consuming systems operate optimally. Data can present both an opportunity and obstacle to this effort. Even if facility teams have the time to look and the knowledge to identify small deviations from optimal performance, the sheer volume of data can be an hurdle.

Automated fault detection and diagnostic methods are one approach to extract insight from facility data and turn that insight into action. Although the built environment industry has yet to adopt a standard framework for fault detection and diagnostics, the concepts are already required in building codes and legislation. ASHRAE 90.1-2022, Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings, the 2015 International Energy Conservation Code, and Part 6 of California Title 24 Energy Efficiency Standards for Residential and Nonresidential Buildings include prescriptive requirements.

Fault detection and diagnostic strategies have two complementary components. They automatically detect common mechanical faults and control errors that can result in suboptimal performance and are predictive of occupant discomfort and equipment failures. These faults are often symptoms of an underlying problem that must be resolved to restore performance. Fault diagnostic solutions should provide automated guidance to facility managers on how to identify the root cause and resolve the detected faults.

In a study on the commercialization of fault detection and diagnostics, the National Institute of Standards and Technology found that “most of today’s emerging FDD tools are stand-alone software products that do not reside in a building control system. Thus, trend data files must be processed off-line, or an interface to the building control system must be developed to enable on-line analysis. This does not scale well because all of the data must be obtained at a single point. A better solution is to embed FDD in the local controller for each piece of equipment, so that the FDD algorithm is executed as a component of the control logic.” Today, many fault detection and diagnostics solutions are delivered as retrospective, historical-data-driven software solutions.

Reliable Controls believes integration of fault detection and diagnostics algorithms at the controller level can be scalable and effective. The primary challenge in an integrated fault detection and diagnostics (IFDD) approach is deployment efficiency. Reliable Controls engineering features such as Templates and the Send Multiple function in RC-Studio® can dramatically reduce the time involved in deploying IFDD logic at the controller level. One of the cornerstones to a simple, flexible, sustainable IFDD solution is IFDD FlexTiles™.


IFDD FlexTiles


FlexTiles are HTML5 animation objects available in RC-GrafxSet®. These animations can be annotated on System Groups with enhancements in Reliable Controls controllers using RC-Studio. IFDD FlexTiles are purpose-built to provide an intuitive, comprehensive operator interface to an IFDD strategy that is simple, flexible, and sustainable. The IFDD operator interaction is captured in a single animation in a way that’s efficient to configure and replicate while supporting customization.

IFDD FlexTiles can be configured to show the performance metrics for an operational mode (e.g., heating or economizer), a piece of equipment (e.g., a variable air volume or rooftop unit), or an entire system or sequence of operation. FlexTiles are like digital flash cards, with a simplified status indication on the frontand details on the back. There are four fundamental operator interface components to an IFDD FlexTile: IFDD status, IFDD rules, IFDD tasks, and IFDD information.


IFDD status


The front of an IFDD FlexTile provides immediate color-coded feedback on the status of the IFDD category (Figure 1):


Figure 1: IFDD FlexTile front displaying color-coded status feedback.


  • No warning: Green (default) indicates there are no active faults.
  • Warning: Red (default) indicates there are active faults.
  • In progress: Orange (default) indicates diagnosis of a fault is underway.


IFDD rules


When an operator clicks an IFDD FlexTile, the digital card flips to display a list of rules on the back. Each IFDD FlexTile is comprised of rules or conditions that indicate a mechanical fault or control error. The status of each rule is indicated using the same color as on the front of the FlexTile.

Figure 2 shows the back of a FlexTile with seven standard rules for a variable air volume terminal unit. Based on the color-coded status feedback:

  • Five rules are green, indicating no active faults.
  • The fifth rule is orange, indicating that troubleshooting of an active fault is in progress.
  • The sixth rule is red, warning of a condition initiated by the violation of a rule.


Figure 2: IFDD FlexTile back .


You can use the same set of rules for hundreds or thousands of IFDD FlexTiles, or use unique rules for an individual FlexTile. The rules are configured in a plain-text support file you can easily customize to reword the rules, translate the default text into a language other than English, and add or remove rules using a text editor.


IFDD tasks


The intrinsic value of fault detection and diagnostics is realized when an operator is not only alerted of poor performance but also empowered to identify and resolve the root cause. The actions taken to troubleshoot and resolve the fault are called tasks.

When an operator clicks any rule on the back of an IFDD FlexTile, an interactive checklist of troubleshooting tasks is displayed. As the operator completes each step, they can select the check box next to the task and move on to the next one. By working through the troubleshooting tasks, the root cause of the fault can be identified and resolved. The troubleshooting progress is saved in the controller, so an IFDD FlexTile can be used to capture the troubleshooting activities of many technicians working simultaneously, activities that take place over time, or activities performed by different teams.

Figure 3 shows some of the tasks to troubleshoot high discharge air temperature on a variable air volume terminal unit. Imagine a maintenance team checking off these tasks virtually. This is useful, beneficial technology.


Figure 3: IFDD FlexTile tasks checklist.


Tasks are defined in the same way as rules, using a plain-text support file that can be referenced by many IFDD FlexTiles or customized for one. This empowers the operator to define specific tasks, change the list of tasks as equipment changes, or describe them in the language of the operations team.


IFDD information files


IFDD FlexTiles also support an optional information file. The file can be formatted as a .txt or HTML file and used to provide additional troubleshooting information, details about the control system or equipment, or dealer contact information. Many IFDD FlexTiles can use the same information file, or individual IFDD FlexTiles can have unique information files. To access the information file, click the information icon (Figure 4) in the upper-right corner on the back of an IFDD FlexTile.


Figure 4: IFDD FlexTile Information file icon.


Lead the way


Identifying equipment faults and control errors saves money, reduces energy consumption, and prevents occupant discomfort. Integrated fault detection and diagnostics FlexTiles provide intuitive insight on facility data and empower building managers to turn that insight into action.