The zone anomaly function detects anomalous thermal zones based on indoor air temperature and airflow control error.

Large commercial buildings are typically divided into multiple thermal zones to allow for separate temperature and airflow control of select portions of the building based on their individual conditioning needs. For example, thermal zones with direct sunlight exposure will command a greater cooling load than zones without direct exposure to offset the external thermal gains. In most HVAC configurations, supply air from the air handling unit (AHU) is directed to variable air volume (VAV) terminals units which service individual thermal zones. Like AHUs, VAV terminal units are a complex assortment of mechanical components, albeit to a lesser extent, and are prone to faults. These faults, hard and soft, can lead to undesirable indoor conditions or even unhealthy indoor air quality.

The zone anomaly function serves to identify anomalous thermal zones based indoor air temperatures and airflow control errors, and can help to identify potential faults in variable air volume (VAV) terminal units which may result in deviation from the intended airflow and temperature setpoint in some thermal zones. The function clusters a number of identified thermal zones based on similar indoor air temperature and airflow control error and generates visuals which plot the clusters of zones with respect to normal indoor air temperature and acceptable airflow control error; this is done separately for the heating (December - February, inclusive) and cooling (May - August, inclusive) seasons.