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The Integrity of Building Analytics

Analytics for building systems, regardless of whether the services are cloud-based or on-site solutions, should be accompanied by constant observation of the data and the analytics themselves.
Levi Epperson
Operations Manager,
Ezenics, Inc.

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Building owners are increasingly aware of and interested in analytics for their building systems and equipment. There are many different vendors available for analytics, including cloud-based and on-site solutions; both methods have merit, depending on the client’s needs. But whether a solution is on-site or cloud-based, how each vendor maintains the integrity of the data and analytics should be fully understood to ensure issues affecting the data and/or the analytics can be quickly addressed. Otherwise you have expensive software producing no results and, consequently, no value.

From our experience, both data and analytics can go awry for a number of reasons, thus an important part of our operation as a company is to continuously monitor all facets of these key areas to ensure quality data is stored and analytics are running and producing results. It is important to note that issues can also be caused by the analytics provider, such as faulty mapping of the data or a processing failure of a specific analytic, making it even more important to ensure that the data storage and analytics are consistently monitored.

Starting with the data, numerous different issues can occur that will trigger an alert in one or more of three data storage metrics that Ezenics tracks. The three primary data storage metrics utilized are last record, frequency, and data errors. Last record shows the last time data has been stored, and there are thresholds in place to alert in case the length of time is too large. Frequency is a measure of how often we receive data for each data point. The ideal frequency is one minute intervals, meaning data is stored for each and every data point once per minute. Similarly, there are thresholds in place to ensure the ideal frequency, with some tolerance, is being met. If either of these metrics exceed the set thresholds, the quality of the analytics will decrease because of the lack of data and/or the low data resolution.

Data errors, the third data storage metric, are indicators of a variety of problems with the data. Ezenics uses many different error codes to help identify the source of the issue. A couple of examples are timeouts, which can indicate a connection problem, and invalid type, which can indicate the expected and actual point type do not match. An example of an invalid type is when we expect a numerical value and are receiving a text value. This error usually indicates a data mapping issue.

The processes and results from an actual client best validate our position that the incoming data needs to be monitored continually. This particular example client (Client A) has hundreds of retail locations across the United States, with several types of equipment (HVAC, lighting, refrigeration, and power meters) monitored in each location. For simplicity, only the information for the HVAC equipment will be explained in this article.

Since Client A has thousands of HVAC assets to monitor, it can be easy to miss issues that occur because the effect on the overall last record, frequency, and data error metrics can be masked by the large number of machines. To account for what might initially be thought of as minimal effects, a different strategy is utilized with the data errors. A report was created to show the overall percentage of data errors at each of Client A’s locations. The report lists the locations with the highest percentage of errors, which are then investigated one by one. In the early stages of this reporting, it was common to see locations with 100% data errors.

In the investigation phase, the building management system (BMS) is a common starting place. The most frequent cause of the data errors is a controller communication issue. This communication issue can occur across the entire location, or only on a few machines via a temporary disablement. It is also common to have noise on the line. The result of this noise is intermittent storage of reliable data. The HVAC equipment will drop offline momentarily and then return, producing data with data errors mixed in.

Another cause is an update to the device list. If a change occurs to the connection details of all or some of the devices in the list, but the data collection process is not updated, then data errors occur. A similar cause is an update to the function block of a controller. In and of themselves, function block changes can affect data storage differently. Sometimes the change can cause all stored data points on the controller to go into error. Other times only some of the stored data points go into error, while the other data points will store values different from what they were storing before. Commonly with Client A, a change of the latter type will result in setpoints storing values that are well outside of the expected range of a setpoint.

Finally, another situation that can occur in a portfolio of hundreds of locations is machine replacement. Communication is key in situations of machine replacement, and when there are thousands of HVAC assets, this reporting method helps minimize any unexpected downtime.

From January through October of 2016, there have been 332 instances of high error percentage locations caught by this reporting method. Over this time period, all of the investigation results into these 332 instances have been shared with Client A. Communication on the causes of the issues helps both sides find, remedy, and prevent issues from occurring as frequently in the future. At the inception of this reporting method, only the locations with 100% data errors were investigated. As time has gone on, and with it familiarity of the causes of the high errors and communication with the client, the investigation has now expanded to include locations with greater than 60% data errors. The goal is to continue lowering that error percentage threshold as solving issues leads to faster resolution and improved reliability with analytics.

Ezenics also oversees the analytics that are deployed to their client’s equipment. Several different measures are regularly examined to ensure the analytics remain fully operational. The first measure is the delay of the implemented algorithms. Since equipment data is always being stored along with timestamps, the algorithms must similarly always process the incoming data. Monitoring the algorithm delay allows for quick response to scenarios in which the delay has risen.

Reliable Controls The second measure for analytics health is errors. The algorithm errors are comparable to the storage errors in that many different error codes are used to point out the problem that has occurred. There are a variety of error codes that identify the specific source of the issue. Three main causes are a server or database issue, a data storage issue, and an implementation issue. Each of the three main causes have several sub-error codes that give more specifics on where the issue originated from, which allows for faster remediation.

The number of results generated by the algorithms is the third measure utilized in maintaining analytic integrity. We record the number of results generated by the algorithms for each location, factor in the client’s typical issue resolution pace, and then compare the current number of results to a running average of previous days. If there are significantly fewer results than expected, the location is investigated to find and correct the issue.

Building owners must be aware of the many ways in which issues occur. Analytics for building systems, regardless of whether the services are cloud-based or on-site solutions, should be accompanied by constant observation of the data and the analytics themselves. Problems can take place at any time and in any piece of the technology, including both the client and provider. Whether the building owner has hundreds of locations across the country or a single office building, it is essential for analytics of every shape and form to be maintained at a high level of operating integrity in order for optimal value to be delivered.

About Ezenics

Ezenics, Inc. is a global leader in automated commissioning, scalable enterprise facility optimization, and energy management solutions for building systems. The core of our automated commissioning is the analytics that continually reviews equipment data to provide prioritized, actionable information that aims to significantly reduce energy, maintenance, equipment, and labor costs for building owners. To ensure the analytics are always able to find and detect issues, Ezenics goes to great lengths to guarantee the data going into the analytics is continually checked for errors, processed, and stored. We exercise the same care with the automated commissioning analytics that use the data to ensure they are processing and producing robust and accurate results.


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