Hi, I am using OS ver 2.6. Currently I am trying to add CO2 concnetration in my zones. I would like to measure CO2 concentration level (ppm). So I went to 'simulation settings' - 'Zone air contaminant balance' - 'Carbon dioxide concentration' - 'on' However I can not add 'Outdoor carbon dioxide schedule name' Please let me know how to add co2 concentration in my model. Best Maki