Indoor CO2 ppm level measurement in Ladybug Tools

Dear @mostapha and @chris

I was wondering if you have added any component to measure indoor CO2 level? As it is provide by some tools (e.g. EDSL TAS software).

This is really an essential need to be added in Ladybug Tools and there have many members asked this before and were looking for a similar case.

Do you have any plan to provide a component for this purpose.

Best regards

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@HardiBarznji ,

We have not made a component to add CO2 sources and sinks to the model but you can add it manually by using the additional strings input to the energy simulation to add some of these objects to the zone:

Here’s and example file showing how to use additional strings (in this case to add an evaporative cooling tower to the model):,0

Thank you so much @chris for the reply.

Actually, I am not familiar with writing IDF’s to the additional strings, I looked at your example and energy plus input/output reference ( ZoneContaminantSourceAndSink:CarbonDioxide ) but I am not sure which IDF example should I use and how to construct the final definition as you have done for the evaporative cooling tower.
If you help me to create something that can measure indoor CO2 level (ppm) in the case of window-based naturally ventilated space, I will be grateful.
I need to test a small room (4 m x 5 m) with a single-sided (or cross ventilation) window and see the effect of window opening ratio’s on the indoor CO2 level (to dilute CO2 generated by occupants + outside CO2).
In EDSL TAS software you can define the outdoor CO2 level (e.g. 400 ppm) and then in the generation rate you can put a number based on the number of occupants and floor area to calculate liter/hr/m2 CO2 generation (see attached figures). I need to write an IDF like this.

Thanks again



Hi again @chris

I have added an IDF example of @TheodorosGalanos (here) to the additional strings but I am not sure if its the correct method or not to what I am looking for?
And how can I read the indoor CO2 ppm level?

Also, for natural ventilation, if I want the windows to be always open (any percentage), do I need to control it with min/max temperatures? Or Can I leave everything else blank but just input the fraction of window operable?
Can you please guide and correct me to do so? Thanks

I have attached my file


Indoor CO2 (690.7 KB)