Only one room non-densely occupied

Hi, following situation: We have a ventilation system which serves only densely occupied spaces except one small office room for one person which is occupied perhaps 1-2 hours a day (so I would call it regularly occupied). Do we really need to install a direct outdoor airflow measurement device due to the one single office room? Or would it be also ok to install a CO2-monitor there (as we will do in all the densely occupied spaces)? Any idea? Just found the answer myself: "where 20% or more of the design supply airflow serves nondensely occupied spaces"...