Fault Detection & Diagnostics

Find what alarms miss.

Your BAS alarms when a value crosses a threshold. But the most expensive problems never cross one — they run inside the normal band, for years. Prescriptiv, our fault-detection engine, reads the trend data your BAS already produces and surfaces them, ranked by what they cost.

01 — The difference

Threshold alarms tell you when something broke. We tell you what's leaking.

Your BAS alarms

  • Fire only when a value crosses a fixed limit
  • Catch obvious, hard failures — after they happen
  • Stay silent on waste that runs inside the normal band
  • No ranking, no dollars, no root cause

LeanFM fault detection

  • Detects patterns and relationships, not just thresholds
  • Surfaces faults that never trip an alarm
  • Ranks every finding by annual dollar impact
  • Shows the evidence, the root cause, and the fix
02 — The fault library

Eight faults that hide in plain sight — and how we find them.

Prescriptiv screens your trend data for each of these patterns. The library grew out of Carnegie Mellon research and keeps expanding as deployments surface new failure modes.

Simultaneous heating & cooling

Two systems fighting in the same air — comfort holds, so nobody sees it, but you pay to heat and cool at once.

Detected from valve/command overlap vs. zone temps

Economizer faults

Dampers stuck or mis-sequenced, paying for mechanical cooling during hours the weather would cool for free.

Detected from damper position vs. outdoor-air temp

Schedule vs. occupancy

Equipment running nights, weekends, and early mornings for spaces that are empty.

Detected from runtime vs. occupancy & schedule

Sensor drift & failure

Sensors reading wrong, so controls act wrong everywhere downstream — while the BAS reports normal.

Detected from cross-point consistency checks

Setpoint drift

Overrides and one-off tweaks that never got reset, compounding quietly year over year.

Detected from setpoint history vs. design intent

Runtime inefficiencies

Cycling, short-starts, and hours far beyond what the load actually requires.

Detected from runtime & cycling patterns

Control sequence problems

Loops that hunt, resets that never engage, sequences that drifted from their design intent.

Detected from loop behavior & reset engagement

Airflow sensor failures

Flow stations reporting fiction — boxes starve or overblow while the BAS shows everything normal.

03 — The output

Every finding, ranked by what it costs.

You don't get a wall of alerts. You get a prioritized list — each finding with the equipment, the evidence, the recommended fix, and the annual dollar value.

Sample finding set · ranked by annual impact

#FindingEquipmentFix effortEst. annual impact
01Simultaneous heating and cooling, weekday occupied hoursRTU-2Sequence change$18,400
02Economizer at minimum position through free-cooling weatherAHU-1Repair / recommission$11,900
03Occupied schedule running 4am and weekends, space unoccupiedVAV-2-08Schedule change$6,200
04Discharge-air reset disabled after a sequence changeAHU-2Re-enable reset$4,100
05Chilled-water pumps staging early against false demandCHW plantStaging tune$3,800

Representative of real deployments. Most top findings are schedule and sequence changes a controls contractor can make in normal maintenance windows — not capital projects.

04 — The engine

Prescriptiv does the screening.

Developed from Carnegie Mellon research, Prescriptiv evaluates every relevant point against the fault library — relationships and patterns a threshold alarm structurally can't see. See how it fits the platform

05 — The engineers

People review it before you see it.

Every finding is checked by LeanFM engineers who do commissioning — so what reaches you is real, prioritized, and actionable, not a noisy feed of false positives.

$0

identified in a single 220,000 sq ft school — led by exactly these faults, none of which tripped an alarm.

Read the K-12 findings
See what's hiding in your building

Point the fault library at your data.

Send us one building's trend data and we'll return the findings — ranked, in dollars, with the evidence. No new hardware.