Requirements II
CASE 1: Mechanically Ventilated Spaces. Monitor CO2 concentrations within all densely occupied spaces (those with a design occupant density of 25 people or more per 1,000 square feet). CO2 monitors must be between three and six feet above the floor. Provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow with an accuracy of plus or minus 15 percent of the design minimum outdoor air rate, as defined by ASHRAE Standard 62.1-2007 (with errata but without addenda1) for mechanical ventilation systems where at least 20 percent of the design supply airflow serves non-densely occupied spaces.