Units and Ranges for IAQ, IAQ accuracy, Static IAQ, CO2 equivalent, breath VOC equivalent

[ehmeducation]

When I start the basic example I get:

Timestamp [ms], raw temperature [⸮C], pressure [hPa], raw relative humidity [%], gas [Ohm], IAQ, IAQ accuracy, temperature [°C], relative humidity [%], Static IAQ, CO2 equivalent, breath VOC equivalent
70, 23.14, 101179.00, 37.06, 46298.00, 25.00, 0, 23.14, 37.06, 25.00, 500.00, 0.50
3070, 23.11, 101173.00, 37.17, 53543.00, 25.00, 0, 23.05, 37.37, 25.00, 500.00, 0.50

After a while it starts to report proper values:

756070, 22.55, 101161.00, 38.09, 97417.00, 21.47, 1, 22.49, 38.22, 23.46, 493.84, 0.49
759069, 22.54, 101157.00, 38.09, 97077.00, 21.47, 1, 22.48, 38.25, 23.46, 493.83, 0.49
762069, 22.54, 101157.00, 38.07, 96460.00, 24.25, 1, 22.48, 38.23, 24.67, 498.69, 0.50

I was wondering what the units and ranges for IAQ, IAQ accuracy, Static IAQ, CO2 equivalent, breath VOC equivalent are?

• For IAQ it seems lower is better? What is the range? best/worst ?
• IAQ accuracy is just a plain 0 or 1 ?
• Static IAQ how is this different from IAQ? Does it have the same 0.0-25.0 range?
• CO2 equivalent is in ppm?
• Is breath VOC equivalent the same a TVOC? What unit is this in?

[handytech · Accepted solution]

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@ehmeducation wrote:

• For IAQ it seems lower is better? What is the range? best/worst ?
• IAQ accuracy is just a plain 0 or 1 ?
• Static IAQ how is this different from IAQ? Does it have the same 0.0-25.0 range?

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Some useful posts to begin with and that should answer most the above:

• BSEC output selection Q&A,
• IAQ accuracy meaning Q&A,
• Community thread about IAQ vs sIAQ and ppm equivalent outputs
• Community thread about the the meaning of the different outputs.

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@ehmeducation wrote:

I was wondering what the units and ranges for IAQ, IAQ accuracy, Static IAQ, CO2 equivalent, breath VOC equivalent are?

• CO2 equivalent is in ppm?
• Is breath VOC equivalent the same a TVOC? What unit is this in?

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Most of the data below can be found in BSEC's Integration Guide and/or bsec_datatype.h.

• Both IAQ outputs are in IAQ index scale. 'IAQ' output is in the range [0-500]IAQ automatically calibrated so that 25IAQ corresponds to typical good air and 250IAQ indicates typical polluted air. 'sIAQ' output has a minimum value of 0IAQ, but it's upper limit is 'unrestricted' (theoretical limit of several thousands typ. never achieved is standard conditions).
• CO2_eq and bVOC_eq are both in ppm scale. Since they are both derived from the sIAQ output, they also have a minimum value (resp. ~400ppm for CO2_eq and ~0.3ppm for bVOC_eq) with pretty large maximum values.