ALTA CO Meter—How the TWA Reading is Calculated

The ALTA CO (Carbon Monoxide) Meter offers a TWA (Time Weighted Average) reading in addition to the instantaneous CO reading. See the formula to calculate this value below.

[For the TWA formula of the CO2 (Carbon Dioxide) Meter, go here.]

TWA Formula

The CO Meter performs a 7.5 Hour TWA reading. The sensor updates TWA every 15 minutes. It averages together an array of 30x CO values (each value a 15-minute average of CO) to calculate TWA. Under the hood, we measure CO every five seconds, and every 15 minutes we take the average of the previous 180 CO readings (15 minute’s worth) and overwrite the oldest element in the 30x array with this new value.

There are plans for updating the TWA formula to eight hours.

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