VAV box starved — airflow below floor with damper saturated open.

Trigger, action plan, and escalation criteria.

Related metric

vav_airflow_delivery

Trigger

measured_cfm / commanded_cfm < delivery_floor AND damper_command ≥ saturation_band, sustained (raises box-starved)

Value drivers

Customer experience Energy savings Asset lifespan

Preconditions

Per-box commanded and measured airflow and damper command mapped from the terminal controller (Desigo DXR2), or read from the BMS under Model B. Each box's design airflow schedule (minimum / maximum CFM) and flow-sensor calibration confirmed at onboarding, and the boxes sharing each AHU recorded, so a clustered shortfall can be read upstream. delivery_floor and saturation_band are configurable server-side attributes.

Human role

Primary at Managed/Optimized — Keedian confirms the shortfall against damper authority, places the cause (terminal vs upstream AHU), and drives the response; a genuine field-device repair (a failed actuator, a collapsed duct) is referred and scoped separately. At Essential the customer's team works the alarm from the dashboard.

Action plan

(1) Confirm the flow calibration first — a VAV flow sensor drifts as its differential ring fouls, so verify the box's flow scaling and design airflow schedule before treating the shortfall as real; an uncalibrated reading manufactures a false starvation. (2) Confirm the damper is genuinely saturated open (past saturation_band) and the shortfall is sustained, not a single interval — a low ratio with the damper mid-travel is a control-loop question, not a delivery fault. (3) Place the cause: a single starved box points at the terminal (stuck damper, collapsed flex duct); a cluster of starved boxes sharing one AHU points upstream — pair with vav_damper_saturation and ahu_duct_static_pressure before dispatching, so a floor-wide static problem is not chased box by box. (4) Tiered response — at Essential surface the starved box for the customer's team; at Managed triage and dispatch a terminal visit; at Optimized command the box within its damper authority (with an audit trail) and refer only a genuine mechanical fault for a scoped field visit.

Escalation

(1) A starved box on a zone with a known heat load (a server closet, a full meeting floor) where comfort loss is imminent → direct action before the complaint; do not hold for the MBR. (2) A cluster of boxes on one AHU losing airflow at once → an upstream static or fan-capacity fault; escalate the AHU (pair with ahu_duct_static_pressure / ahu_fan_vfd_performance), not the individual boxes. (3) A box that keeps starving after a terminal repair → flag the controller or flow sensor for a deeper look rather than re-dispatching the same fix.

Prevention

(1) Record each box's design airflow schedule and verify the flow-sensor scaling and damper travel range at onboarding, so a shortfall reflects the terminal and not a calibration error. (2) Weight the alarm to a sustained shortfall with the damper saturated open rather than single intervals, and trend per-box delivery next to the serving AHU's duct static so an upstream cause is visible. (3) Maintain a per-box delivery log so a recurring terminal fault, or a box that starves whenever the floor loads up, is visible across visits.