4 FM quick reads on fault detection and diagnostics
1. Data Issues Are Critical With Fault Detection And Diagnostics (FDD)
Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. Facility managers who are considering fault detection and diagnostics tools should be aware of the importance of data and network issues. Here are some points to keep in mind.
Lack of Data. Fault detection and diagnostics tools rely on data from building automation systems. If there are not enough sensors, if the sensors are inaccurate, or if the building has a legacy control system and for some reason accessing the BMS database or controllers is difficult, there can be issues with obtaining the accurate data required.
Using the Diagnostic Data. Many of the fault detection and diagnostics software tools can provide information to the technician or engineer regarding potential corrective actions. This information needs to be integrated into the work order system, which may be one application in a whole suite of facility management applications, in order to use the information effectively.
Applications in the Cloud. Many companies offering fault detection and diagnostics software will provide the application on the client site, but have an option to provide the application as "software as a service" (SaaS) or in "the cloud." Essentially the vendor hosts the application, and the facility manager accesses the application through a normal web browser. This can be an issue with many corporate IT departments because of the need to pierce the corporate IT firewalls and security to get to the BAS data the application needs.
Prognostics Data. While fault detection and diagnostics tools seem inherently capable of providing prognostic data — that is, it can analyze fault conditions or degradation faults and predict when a component will fail or not be able to perform correctly — very little has been developed in this area. In addition, prognostic data would allow for more proactive, condition-based maintenance, which would be a different approach for facility management organizations that are reactive and corrective.
2. With Fault Detection And Diagnostics (FDD), Take Close Look At Buildings, Software Capabilities
Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. As promising as fault detection and diagnostics is, facility managers need to take a close look at their buildings and at the capabilities of available software tools before rushing out to install a fault detection and diagnostics application. Consider these issues.
Handling Fault Information. Facility management organizations need to decide how best to handle the fault detection and diagnostics information. A "fault" identified by a fault detection and diagnostics application indicates that the system is not performing optimally. This is different from a system alarm indicating some criticality and need for immediate action. In many facility management organizations, both alarms and faults automatically trigger a work order, but do so identifying different priorities for the work order. Other organizations set the faults aside and then periodically meet to discuss the remedies.
Rules Specific to Building Systems. The rules apply to specific HVAC relationships and equipment, and facility managers need to be assured that their specific building systems are or can be addressed by the fault detection and diagnostics software application. Many products start with a standard set of rules, which may address similar or smaller buildings or HVAC configurations, and then add rules developed by others or by the end users themselves.
For larger buildings, fault detection and diagnostics does not come right out of the box. Almost every sizable building and HVAC system is slightly different, so the rules have to be customized. That's not necessarily a bad thing as the customized rules are likely to be more accurate and based on specific building needs, but customization requires additional installation time.
Lack of Applications for Emerging and Other Systems. Fault detection and diagnostics applications are primarily HVAC-focused. There is an opportunity for the industry to take the rules-based approach to other systems, such as solar, wind, geothermal, or power management.
Alternative Ways to Deploy Capability. Fault detection and diagnostics is simply a software application. At some point in the future, control and equipment manufacturers will simply integrate fault detection and diagnostics software routines into their controllers.
3. Understanding How Fault Detection And Diagnostics (FDD) Tool Works
Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. With interest growing, facility managers should understand how fault detection and diagnostics (FDD) tools work.
FDD is an analytic tool that identifies faults in HVAC systems and provides advice about how to address those problems.
More technically, fault detection and diagnostics is based on research into faults in HVAC systems and the development of hierarchical relationships and rules between the different equipment and processes that make up the HVAC system.
A key relationship is between “source" and "load." A chilled water plant supplying air handling units is one relationship: The chilled water plant is the single "source" and the air handling units are multiple "loads." Another relationship is an air handling unit delivering supply air to terminal units: The air handling unit is the single "source" and the terminal units are the multiple "loads." It is these relationships and the rules within the relationships that are at the core of fault detection and diagnostics.
Fault detection and diagnostics tools basically monitor the data points in the HVAC control system in real-time (temperatures, flows, pressures, actuator control signals, etc.) and then apply a set of rules. For example, there is a set of rules for systems consisting of a chiller, a boiler, air handling units receiving hot and chilled water, and terminal units receiving supply air from the air handling units. A different set of rules would be applied if there was staged heating and cooling directly at the air handling unit or for single-zone air handling units. There are also different rules for the same equipment based on the state of the equipment. For example a chiller will have a certain set of rules when it is off, another set of rules at start-up and still another during its steady state. The analytics tool will identify a fault if the real time data doesn't conform to the rules or the optimal relationship.
Usually the tool would see faults in both the "source" and the "load," but the assumption is that the real problem is a fault in the "source," so the faults in the "load" should be suppressed. A simple example is a chiller supplying water that is too warm to an air handler. The air handler's cooling coil valve then becomes 100 percent open and supply air temperature is above set point, resulting in the VAV not being able to maintain air temperature in its zone. The software would get faults for all three pieces of equipment (chiller, air handling unit and VAV), but suppress the faults for the "loads" — the air handler and the VAVs.
The real beauty of the rule-based approach is the simplicity and transparency of the rules and the identification of the causality. Because most of the data points in a building are related to HVAC systems, there's just more data to analyze resulting in more reliable results.
4. Fault Detection And Diagnostics (FDD) Is Attracting Industry Interest
Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. Fault detection and diagnostics is attracting industry interest.
If you are buying books or music from an online site, it's likely that the e-commerce company analyzes your purchases, creates a profile of what type of books or music, authors or performers you like, and then proactively sends you email regarding other items you may be interested in purchasing. Those firms regularly mine data to improve their business performance. Generally facility managers haven't fully embraced such data analytics. However, that is changing.
Today, a new generation of analytics is becoming available to facility managers. The most prominent of these new analytics tools is fault detection and diagnostics. Fault detection and diagnostics finds problems within building systems that are causing the HVAC system to waste energy.
The idea of fault detection and diagnostics for HVAC systems is not new. Research, development and testing of fault detection approaches have been around for about 20 years or so. What is new is the increased interest in and actual use of fault detection. For example, Microsoft has seen promising results with fault detection and diagnostics. Another example of industry approval of data analytics and fault detection and diagnostics came in October 2011, when the U.S. Green Building Council announced a technology agreement that would allow building owners to use an automated fault detection tool with the LEED Online platform, thus supporting the commissioning of buildings. USGBC's interest is that the tool generates reports for LEED Online, including diagnostic functions and faults during the building's performance period.
Another sign of industry interest comes from a Lawrence Berkeley National Laboratory study on monitoring-based commissioning, which uses building diagnostics. Lawrence Berkeley established an average energy savings of 10 percent through the use of monitoring-based commissioning, with as much as 25 percent in some cases.
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