What is the Difference Between AFDD™ and a BMS?

Benjamin Kelderman, Jose Montoya Segnini

With the goals of increasing building energy savings, reducing maintenance costs, and improving occupant comfort, Automated Fault Detection and Diagnostics™ (AFDD™), has been developed to enhance the information that a Building Management System (BMS) already provides. In this article, we will describe what AFDD™ is and how it differentiates from the capabilities of a typical BMS. In addition, we will review examples and discuss the benefits that AFDD™ brings to a building operator or owner.

In order to understand the differences between a BMS and AFDD™, let’s start by reviewing what a BMS is and does. A BMS controls and monitors a building’s mechanical and electrical equipment, allowing for centralized management of critical systems and includes functions such as temperature control, equipment scheduling, and monitoring building conditions with basic trending of key data points. When used correctly, a BMS can enable some of the benefits mentioned above: energy savings, reduced maintenance costs, and improved comfort. However, AFDD™ will optimize and maximize these benefits.

AFDD™ automatically evaluates building system and equipment performance by continuously analyzing real-time building data. It provides valuable information about how equipment is actually performing and can diagnose whether sensors or equipment inside of a building are degrading, determine if the machine is not adhering to its initial design intent or programming, does not have enough capacity, or if it is influencing an adjacent zone or equipment. Additionally, AFDD™ analytics provide an enhanced description of issues, identify the underlying causes of problems, and prescribe potential fixes that streamline workflow.

To illustrate the difference between a BMS and AFDD™, envision a packaged rooftop unit that has a faulty cooling compressor. With a typical BMS, a technician or facility manager will not identify that there’s a problem until the compressor has been malfunctioning for some time; most likely only after receiving complaints about the zone being too warm on hot days. Whereas, with the added insight of AFDD™ continuously monitoring the data and making a proactive diagnosis, the technician would be alerted that the unit’s supply air temperature is too warm and the space temperature is not reaching its intended setpoint. The facility team would be able to apply a fix before the issue impacts occupant comfort, and in addition prevent the machine from using excessive energy while running continuously as it fails to maintain the zone temperature setpoint.

BMSs and AFDD™ have some similar capabilities. BMSs control and monitor data, and can display alarms for very basic issues such as an incoming value being higher than expected. Many BMSs (depending on age) generate alarms based on raw incoming data without validating the data first. AFDD™, on the other hand, first checks to make sure that incoming data is within a normal or expected range before performing further analysis using sensor equipment data. BMSs generally only compare a single or few points to a threshold, while AFDD™ runs many, often disparate equipment and system data points through its algorithms in order to identify and present the user with problem diagnosis, cause, resolution, and financial impact.

While a good BMS system can provide effective control of a facility, overlaying an AFDD™ solution can enhance it by enabling a proactive maintenance approach that prioritizes critical issues and provides operators with a path of investigation and possible solutions. As shown in the example of the faulty cooling compressor, AFDD™ reduces energy consumption and occupant complaints by proactively pinpointing faults and identifying the associated issue cause and resolution. In summary, while a BMS can provide good control of a buildings equipment and systems, implementing an AFDD™ solution will provide oversight of the control system, ensuring the building runs as the designers intended and that equipment operates efficiently and occupants are provided with a comfortable environment.