Compliance of Sensirion’s VOC Sensors with Building Standards

The AirGradient air quality monitors AirGradient ONE and AirGradient Open Air contain the Sensirion SGP41 TVOC/NOx sensor module. This is one of the most accurate TVOC module on the market.

By default this sensor module provides index based sensor measurements. However these index based values can be converted into absolute measurements suitable as a base for building certifications.

The formula used is:

TVOCEthanol [𝑝𝑝𝑏] = (ln(501 − 𝑉𝑂𝐶𝐼𝑛𝑑𝑒𝑥)− 6.24) ∙ (−381.97)

This result is visible on the AirGradient dashboard as “TVOC (ppb)”.

IMPORTANT: For the correct calculation of this absolute value, the “Normal learning time offset” in the General Settings, Calibration Settings Menu needs to be set to “720”.

For further information and how to apply this formula to various building standards, please read the Compliance of Sensirion’s VOC Sensors with Building Standards Document.