Whether each VAV box actually delivers the supply airflow its control loop is calling for — measured airflow against the box's commanded setpoint. A box that sits below its airflow setpoint while the damper is already open is starved: a stuck damper, a collapsed flex duct, low upstream static, or an undersized box. The earliest per-terminal signal that a zone is about to lose comfort, weeks before the complaint.
How closely each variable-air-volume box delivers the supply airflow its control loop commands — measured airflow as a share of the commanded setpoint, over the intervals the box is actively calling for air. It is a per-terminal equipment-performance signal about whether the box can do its job, distinct from Temperature Compliance (the zone outcome) and Setpoint Compliance (operating discipline).
Per box, the delivery ratio over the period is measured_cfm / commanded_cfm × 100, evaluated only over intervals where the box is calling for airflow and the damper is not at its minimum stop, so a box correctly parked at minimum is not scored as under-delivering.
A shortfall is confirmed only when the box cannot close the gap with damper authority it still has — a low ratio with the damper already near 100% open is a genuine starvation signal, while a low ratio with the damper mid-travel is a control-loop or calibration question, not a delivery fault.
The signal is read per terminal and rolled up to the floor and the serving AHU, because a cluster of starved boxes on one air handler points upstream — to duct static pressure or fan capacity — rather than to any single box.
| Range | Classification | Interpretation |
|---|---|---|
| Delivery ratio ≥ 95% of commanded airflow | Expected — delivering | The box meets the airflow its loop calls for; comfort and ventilation on that zone have the air they need. |
| Delivery ratio 80 – 94% with the damper open past ~90% | Under-delivering — monitor | The box is calling for more air than it receives; scope the terminal (damper travel, flex duct, upstream static) before the zone drifts out of range. |
| Delivery ratio below 80% with the damper saturated open | Starved terminal — investigate | The box cannot get the air it needs; a stuck damper, a collapsed duct, or an AHU not holding static — pair with ahu_fan_vfd_performance to place the cause. |
Reference bands only. Calibrate the delivery floor and the box minimum against the design airflow schedule for each box before reporting, because minimum ventilation stops and design maximums differ box to box.
The per-box target is to deliver ≥ 95% of commanded airflow whenever the box is calling for air, with a saturated damper below target treated as a starvation finding rather than a tuning question. Agree the floor per floor against the design airflow schedule.
The table below shows how moving VAV Airflow & Damper Performance impacts each customer value driver the product is designed to improve — the metric page explains the mechanism; the product pages express the magnitude.
| Value driver | Impact strength | How VAV Airflow & Damper Performance moves this lever |
|---|---|---|
| Customer experience | Direct, primary | A box that cannot deliver its commanded airflow is the direct mechanical cause of a warm or stuffy zone the moment the load rises. Catching the shortfall per terminal turns a comfort complaint that would surface at the tenant's desk into a scoped terminal fix. Magnitude is expected (pending validation) — offices have no named Keedian reference deployment yet. |
| Energy savings | Indirect | A starved box drives its zone to override — occupants drop setpoints or call for more cooling floor-wide — and pushes the AHU to raise duct static for one bad terminal. Fixing the delivery fault removes the reason the whole floor is run harder than it needs to be. |
| Asset lifespan | Indirect, leading indicator | A damper that has failed toward a fixed position, or a flow sensor drifting, shows first as a delivery shortfall. Flagging it as a scoped terminal item turns a future no-cooling call into a planned actuator or sensor replacement. |
The table below summarizes the alarms that fire directly from VAV Airflow & Damper Performance. Each row links to the full operational detail (trigger, preconditions, action plan, human role, escalation, prevention) in the SOPs catalog.
| Alarm | Description | Severity | Tier | AI executes? | Value drivers | SOP |
|---|---|---|---|---|---|---|
| VAV box starved — airflow below floor with damper saturated open | A VAV box is holding below its airflow delivery floor while its damper is already saturated open — it is calling for air it cannot get. Confirmed against damper authority (a low ratio with the damper mid-travel is a control or calibration question, not a starvation fault), so a genuine shortfall means a stuck damper, a collapsed flex duct, or the AHU not holding static for that box. Left alone, the zone drifts warm the moment the load rises. | High | Essential | Hybrid | Customer experience · Energy savings · Asset lifespan | Open SOP → |
| Minimum ventilation breach — occupied box below its ventilation floor | A VAV box is running below its agreed occupied minimum airflow during scheduled-occupied hours — the ventilation floor the zone needs for indoor air quality even when it is not calling for cooling. Whether from an over-aggressive energy setback that starved ventilation, a damper stuck below minimum, or a minimum set too low at commissioning, the result is a quietly under-ventilated occupied zone — the stuffy, high-CO2 room no temperature reading explains. Read against the confirmed design minimum, never a computed ventilation rate. | Medium | Essential | Hybrid | Customer experience · Energy savings | Open SOP → |
| VAV loop hunting — damper and zone temperature oscillating around setpoint | A VAV box's control loop is hunting — the damper command and the space-temperature error oscillating around setpoint during steady load instead of settling on it. It wears the modulating damper actuator with continuous travel, unsettles the zone (temperature drifting up and down, drafts as airflow swings), and pushes needless airflow swings back to the AHU's static and fan control. Caught early, a future failed-actuator no-cooling call becomes a planned retune or a scheduled actuator replacement. | Medium | Essential | Hybrid | Asset lifespan · Customer experience · Energy savings | Open SOP → |
More alarms in development (single-metric): a slow-degradation trend that flags a box losing delivery before it saturates, and a flow-sensor-drift watch. Composite terminal alarms that weigh this metric's airflow, damper-saturation, ventilation and loop-stability alarms together will appear in a future release.
The action plan for each alarm lives on its own SOP page in the SOPs catalog — with the diagnostic steps, human role, value drivers, escalation, and prevention specific to that alarm. The list below maps each alarm to its SOP.
A VAV flow sensor reads pressure across a differential ring and drifts as it fouls; a shortfall against commanded airflow can be a mis-scaled or drifted flow sensor rather than a real delivery fault. Confirm the box's flow calibration and design airflow schedule before reporting a terminal as starved, so a calibration error is not dispatched as a mechanical repair.
What Keedian does with a delivery shortfall scales with the tier. At Essential the customer's team sees the starved box and works it themselves; at Managed, Keedian Ops runs the alarm, triages, and dispatches; at Optimized, Keedian commands the terminal directly (within the box's damper authority, with an audit trail) and refers only a genuine mechanical fault — a failed actuator or a collapsed duct — for a field visit.
Per-alarm escalation criteria live in the Escalation block of each SOP in the SOPs catalog. The patterns below are metric-level — read from the portfolio view, not from any single alarm firing.