ZoneAirContaminantBalance E+ object

I blame Chris for pointing me to this new and unknown world.

The result will be a possible rampage of questions to all you wonderful people! This one has to do with the above mentioned object in E+. According to the E+ I/O reference the implementation is something like this:

ZoneAirContaminantBalance, Yes, !- Carbon Dioxide Concentration
Outdoor CO2 Schedule, !- Outdoor Carbon Dioxide Schedule Name
Yes, !- Generic Contaminant Concentration
Generic Contaminant Schedule; !- Outdoor Generic Contaminant Schedule

It seems that can be an easy way to get a quite useful information on building performance (CO2 concentration in your zones).

However, and since I have never used the additional strings in HB, I would welcome your advice on the additional string below. Would something like this be enough? I apologize I cannot test it atm on this computer.

ZoneAirContaminantBalance, Yes, !- Carbon Dioxide Concentration
Default outdoor CO2 levels 400 ppm, !- Outdoor Carbon Dioxide Schedule Name
No; !- Generic Contaminant Concentration

Default outdoor CO2 levels 400 ppm, !- Name
Any Number, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 24:00, !- Field 3
400 ; !- Field 4

Output:Variable, *, !- Key Value
Zone Air Carbon Dioxide Concentration, !- Variable Name
timestep; !- Reporting Frequency

Also, is anyone aware of the accuracy of this object? I am guessing it should include air extraction and/or MV?


I have not used this object but, if you are interested in trying to get the CO2 concentration in the room, I would just use the “airFlowVolume” output of the Read EP Result component along with the occupancy schedule to estimate the hourly CO2 concentration. That output of airFlowVolume is a sum of all outdoor air entering the building.


Dear Theodore and Chris,

Thanks for your efforts.

Have you added any component in Ladybug Tools that can measure the indoor CO2 level?


Hello @TheodorosGalanos
Have you used this IDF to the additional strings of EP in HB?
I also need to measure zone CO2 concentration, but still not reached the results.


Hi Hardi,

I just wonder to know can you model indoor CO2 concentration with ladybug-honeybee? any hint for reading results?

CO2 objects aren’t natively supported in Honeybee and you would have to use an OpenStudio Measure or additional IDF strings to add the CO2 objects to your Honeybee model.

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Thanks a lot Chris for the reply.