Results and discussion
Ventilation systems in the classrooms consisted of
single-zone room units (i.e. residential style upflow
furnace-type systems, unit ventilators, roof top units
serving one room only, and fan coil units), which were
ideal for the method of approximating ventilation rates
using CO2 concentrations. The mean of the ventilation
rates calculated from the classrooms was 3.88 l/sperson
(range 0.90–11.74), i.e. approximately half of
the ASHRAE Standard 62 recommended minimum.
These data indicate that the amount of outdoor air
being mechanically provided to the rooms was in the
vast majority of cases less than the minimum standard.
It is worthwhile to note that although all classrooms
were occupied during the 4–5 h test period, in many
instances there was some degree of transitory occupancy
(i.e. lunch breaks, playground breaks, etc.).
Because of these occurrences (in addition to cases
where ventilation rates were extremely low, i.e.