LB-17-C066 — Ventilation and Corresponding CO2 Levels in High School Classrooms

This paper reports findings about ventilation taken from a larger study of 30 high school classrooms in central Texas. Classrooms in portable buildingsand permanent structures were sampled twice for four consecutive school days in the 2015-2016 school year. Carbon dioxide (CO2) concentrations weremeasured in the supply airstream and the general room space. Average and peak CO2 concentrations were used to estimate the risk of cold and flutransmission in schools during months of elevated sickness. It was found that average CO2 concentrations during the occupied period in 81% of classroomssampled in Fall 2015 and 72% of classrooms sampled in Spring 2016 exceeded the ASHRAE 62.1 recommendation for fresh air. When peak CO2concentrations during the same time periods were considered, 92% and 95% of classrooms in Fall 2015 and Spring 2016 exceeded this recommendation,respectively. Nighttime air exchange rates and occupied fresh air exchange rates were calculated for portable and permanent classrooms, and findings indicatethat portable classrooms are dominated by occupant behavior, leaky building envelopes, and weather patterns.