To get a comfortable indoor enviroment there are a couple of guidelines to follow.
In schools and community centers CO2-levels above 1000 ppm is concidered as an inconvenience.
Carbon dioxide should be measured in areas where people spend time most of their time. The measuring points should be at a hight of 1.1 meters (seated activities) or 1.7 meters (standing activities). The meter should also be placed at least two meters away from people directed at the meter and one meter away from people looking in other directions. This to avoid direct human exhale.
Logging in schools and other buildings
In classrooms during lesson the CO2-levels should be measured at several points in this area. Doors and windows must be closed.
In a classroom it is common to register the carbon dioxide for one day with a sample rate of 15 minutes. In an office landscape, where the movements are slower, it may be appropriate to measure for a week.