Data availability: the metric behind every credible report

A concentration without availability is a claim

A signed emissions report that shows 98% compliance and says nothing about how many hours were actually measured is easy to produce and hard to defend. Ghana's EPA, like other competent authorities, reads the availability figure as closely as the concentration. If the instrument was offline, in calibration, or delivering invalid packets, those hours are not a clean stack. They are missing evidence.

GOCEMS treats availability as part of the reading, not a footnote assembled at month-end. Each interval carries instrument state. Valid, calibration, communication loss and excluded maintenance are counted separately so the total can be explained.

What goes into the number

Valid intervals are readings that passed validation — range checks, analyser status, and the averaging rules for that stack and parameter. Calibration and QAL-style windows are excluded from the availability total; they are not hidden and they are not filled with the last good value. Logger or link downtime is a gap. It must not be stored as a zero, because a zero looks like a plant that stopped emitting.

Thermal plants feel this first. Start-up, peaking and fuel switching already change the stack chemistry. If a logger drop during a start-up is later read as a zero, the availability figure and the mass total are both wrong. The control room saw the gap. The signed pack has to show the same gap.

Why a quiet zero is the failure mode

Spreadsheets fail here in a predictable way. A missing hour is left blank, then someone fills it, then the blank becomes a zero because the chart cannot plot empty. Downstream, the average looks better than the plant. That is how audit season turns into a reconstruction project.

The GOCEMS data path is built so that failure is visible: probe, logger, encrypted ingest, validation, then the record. If a step fails, the interval is flagged. Alerts can fire on availability as well as on exceedance, because a plant that goes dark is as relevant to the permit as a stack that runs hot.

What the regulator can actually sign

A credible pack states the concentration, the limit, the averaging window, the exceedance history, and the availability for the period. Those fields travel together in GOCEMS so operations, EHS and the regulator are not arguing about which hours counted. Demonstration figures on this website are not live plant readings. Production availability is generated from the facility's own validated series.