4 FM quick reads on fault detection and diagnostics
1. Microsoft Finds That Fault Detection Saves Energy
Today's briefing comes from Rita Tatum, contributing editor for Building Operating Management. The value of intelligent buildings compounds when applied across a corporate or governmental real estate portfolio. Microsoft has about 125 buildings totaling roughly 15 million square feet on its Redmond, Wash., campus, as well as another 15 million square feet spread across the globe. The Redmond campus is the size of a medium-sized city, says Darrell Smith, director of facilities and energy for real estate and facilities.
Buildings were built at different times and design standards were not initially set. So the campus had many disparate BAS systems. "Nothing was talking to each other," says Smith. "Reporting was labor intensive." To prepare a quarterly report on energy use meant physically going into several tools to extract the information from every meter, which took weeks.
Ripping out and replacing $60 million of BAS systems to make everything the same was not feasible for a company with literally millions of data points. The company was looking for off-the-shelf solutions built on Microsoft technology that would provide fault detection and diagnosis, alarm management and energy management on one platform.
The company expects to reduce energy consumption by 10 percent. Microsoft began studying its options in 2009. By 2011, the company decided on three potential smart solutions from three different vendors and began installing and monitoring them in 13 buildings, representing about 2.6 million square feet of space. Some of the buildings were nearly brand new while others were more than 20 years old. The analytical layer from each vendor was installed above the existing building management systems.
Following a year of study and evaluation, Smith says all three program components performed well, "but fault detection turned out to offer the largest value. We saw a 17 percent savings in one building in just one week," he says. Now, Microsoft has selected one vendor from the three and is deploying the solution across its whole Redmond campus.
2. 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.
3. 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.
4. 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.