Plant efficiency drift (kW/ton above design).

Trigger, action plan, and escalation criteria.

Related metric

plant_efficiency_kw_per_ton

Trigger

kW/ton > design_kw_per_ton × (1 + drift_margin), sustained and load/wet-bulb-normalized

Value drivers

Energy savings

Preconditions

Plant power metering and chilled-water flow both instrumented (tons = flow × ΔT); the meter boundary (chiller-only vs full plant) fixed per plant; the plant's design / commissioned kW/ton recorded as the baseline. Where flow or power is not metered, the metric — and this alarm — is not offered for the plant rather than estimated.

Human role

Primary — Keedian reports and refers; it does not stage the plant, reset water temperatures, or command the equipment. Operators normalize for load and weather, confirm the drift is plant-specific, and communicate it with a candidate cause.

Action plan

(1) This alarm is not critical — it is communicated, not dispatched. Handle it at cadence (weekly ops review / MBR), not as an out-of-cycle event. (2) Normalize for load and wet-bulb temperature first — kW/ton rises legitimately at high load and high wet-bulb; do not read a hot-day excursion as degradation. (3) Confirm the drift is sustained against the plant's own design figure, not a single interval, and that the meter boundary matches the baseline (a full-plant figure is inherently higher than chiller-only). (4) Where several plants in a region drift together with the weather, present it as expected context in the MBR rather than a finding. Refer only the genuinely plant-specific drift to the customer's plant-service vendor, with a candidate cause (condenser-tube fouling, low chilled- or condenser-water flow, poor staging for the load).

Escalation

(1) Plant running persistently above its design kW/ton across multiple months after a vendor referral → a plant-inspection or CapEx candidate; carry it into the MBR with the excess energy quantified against the plant's own baseline (magnitude expected — pending validation; offices have no named Keedian reference deployment). (2) Efficiency drift co-occurring with a declining evaporator or tower ΔT → a fouling or flow lead; pair the two signals for the vendor. (3) A metering or flow-integrity fault that makes kW/ton unreliable → pause efficiency reporting for the plant until the instrumentation is reconciled, rather than reporting false drift.

Prevention

(1) Confirm plant power metering and chilled-water flow are present and fix the meter boundary before activating the metric; record the design / commissioned kW/ton as the baseline. (2) Set the drift margin against the plant's design figure and weight it to sustained excursions rather than single intervals; attach load and wet-bulb context to every reading. (3) Trend kW/ton next to evaporator and tower ΔT so a fouling or flow cause can be read alongside the efficiency loss, and keep a per-plant efficiency log so a seasonal fouling pattern is visible year over year.