Fault Detection and Diagnostics (FDD) is the process of identifying problems in equipment and analyzing available data to determine the root cause of the issue.
Undetected faults in equipment can lead to underlying problems. A "fault" does not have to be the result of a complete failure of a piece of equipment. For instance, a problem might be defined as non-optimal operation or a drift in performance. In commercial real estate, root causes of non-optimal operation might be equipment failures, but problems might also be caused by poor choice of operating targets, poor controller tuning, or human error. A fault may be considered a binary variable (”OK” vs. “failed”), or there may be a numerical “extent”, such as the amount of a leak or a measure of inefficiency.
Fault diagnosis is pinpointing one or more root causes of problems, to the point where corrective action can be taken. Automated fault detection and diagnosis depends heavily on input from submetering solutions and derived measures of performance.