BAS-404 Visual Aid Library
Figure-use rule
Each figure is an orientation and reasoning aid, not a project drawing. Learners must pair it with the current sequence, point list, wiring/piping documents, manufacturer instructions, and as-found evidence.
Normal-rule anchor
A graphic exists to support safe, timely decisions; it is not a digital copy of every available point or a showcase of animation.
Case overlay
Operators report that an AHU graphic looks impressive but cannot answer why a floor is hot or whether the fan is proven.
Calculation/evidence callout: Rank tasks by frequency, urgency, consequence, time-to-answer, error rate, and required evidence.
Normal-rule anchor
A learner or operator should always know where they are, what they are viewing, what serves it, and how to move one level up or downstream.
Case overlay
The same VAV is reachable from a floor plan and an AHU tree but displays different names and no shared breadcrumb.
Calculation/evidence callout: Count navigation steps and dead ends for defined tasks; verify identity consistency and maximum time-to-target.
Normal-rule anchor
The figure should preserve process direction and control relationships while omitting detail that does not help the operator decision.
Case overlay
A cooling-coil valve appears downstream of the discharge sensor on the graphic even though it is physically upstream.
Calculation/evidence callout: Verify process path order, sensor/actuator placement, equipment counts, and orientation against current drawings.
Normal-rule anchor
A writable field must reveal range, units, effective value, priority/source, authorization, expiration/release, and result; a displayed command is not proof.
Case overlay
A fan button turns green when commanded, even though proof is false and a local HOA switch is in OFF.
Calculation/evidence callout: Reconcile setpoint, value, command, priority, proof, timing, and process result; calculate error and age.
Normal-rule anchor
Color and animation are reserved for meaning and urgency; normal equipment does not need to compete with abnormal evidence.
Case overlay
A red/green-only floor plan blinks every operating fan and gives no keyboard focus indicator.
Calculation/evidence callout: Measure contrast against the selected accessibility criterion, count state meanings, and verify every color state has text/icon/shape redundancy.
Normal-rule anchor
A template must surface missing identity, units, quality, or points; silent fallback can make wrong equipment appear normal.
Case overlay
A VAV template is copied to fan-powered boxes and silently binds the fan status field to a reheat command.
Calculation/evidence callout: Calculate binding coverage, exception count, duplicate effort, and regression pass rate across sample equipment.
Normal-rule anchor
A heat map compares like with like and shows missing/stale data; color without a legend, scale, timestamp, and quality can manufacture a pattern.
Case overlay
A floor map highlights temperature deviation, but half the zones are unoccupied and three sensors are stale.
Calculation/evidence callout: Calculate deviation from active setpoint, occupancy-filtered counts, data-age thresholds, and aggregate values without averaging incompatible states.
Normal-rule anchor
An alarm link should answer what happened, where, when, current impact, relevant evidence, authorized next action, and whether normal was restored.
Case overlay
An operator receives a low-temperature alarm with no equipment context, no trend, and a generic acknowledgement button.
Calculation/evidence callout: Measure time-to-context, linked-evidence completeness, and event/trend clock alignment.
Normal-rule anchor
Empty, zero, stale, loading, unavailable, and normal are different states and require explicit treatment.
Case overlay
On a tablet, a delayed API response causes values to display as zero and hides the stale timestamp.
Calculation/evidence callout: Measure load/render time, refresh age, touch target, keyboard path, and percentage of points with visible quality and timestamp.
Normal-rule anchor
Designer confidence is not usability evidence; representative users must complete consequential tasks without unsafe interpretation or hidden coaching.
Case overlay
A technician can use the new AHU graphic, but two novice operators misread a gray failed sensor as a normal inactive value.
Calculation/evidence callout: Calculate task success, time, error/assistance rate, severity-weighted issue count, and regression closure.