Ventilation Rates and School Performance

Children in a classroom.

Four studies in schools have investigated the linkage of ventilation rates to objectively measured, as opposed to self-reported, school work performance. A Norwegian study [12] performed in 35 classrooms located in eight schools used reaction times in a standard test to measure student concentration and vigilance. Reactions were 5.4% faster with a ventilation rate of 8.1 air changes per hour (ach) corresponding to 26 cfm per person compared to 2.6 ach (8 cfm per person). A U.S. study [13] in 5th grade classrooms from 100 schools, used student performance in standard academic tests as the measure of performance. In 87 classrooms, ventilation rates were less than the 15 cfm per student minimum ventilation requirement in the ventilation standard applicable at the time of the study [14]. In these classrooms, performance in both math and reading tests increased with ventilation rate. The percentage of students passing the standardized math test increased by 2.9% (95% confidence interval was 0.9% to 4.8%) for each 2.1 cfm per student increase in ventilation rate. The percentage of students passing the standardized reading test increased by 2.7% (95% confidence interval was 0.5% to 4.9%) for each 2.1 cfm per person increase in ventilation rate. The analysis controlled for the socioeconomic status of the students and the number of students transferring into and out of the schools. These findings were highly statistically significant, i.e., unlikely to be chance findings. When data from all 100 classrooms were considered, test scores in both math and reading scores increased as ventilation rates increased to approximately 15 cfm per student but then test scores diminished, on average, at higher ventilation rates. However, there was a great deal of variability in test scores from the small number of schools with the highest ventilation rates, thus, the trends in test scores as ventilation rates increased above 15 cfm was highly uncertain. In a Danish study performed within four classrooms [15-17], Wargocki and Wyon used performance tasks representing various aspects of schoolwork, from reading to mathematics that were embedded into the normal school work. The speed and accuracy of task performance was assessed. This study reported an 8% increase in speed of school work tasks with a doubling of ventilation rate. There was no statistically significant influence of ventilation rate on the number of errors made by students. Figure 3 provides more detailed results from this study.

Figure 3. Student performance versus ventilation rate based on study in Denmark [17]. Performance was based on the speed (left figure) and accuracy (right figure) of completing various school work tasks. The various data points represent results from multiple experiments and multiple types of work tasks. [Figure 3 reproduced with permission.]

In Japan, college student performance in classroom settings and in a laboratory setting on standardized tests was evaluated at different ventilation rates [18, 19]. In three tests implemented in the field study, one on theory and two involving memorization, performance improved 5.4%, 8.7 %, and 5.8%, respectively, with increases in ventilation rate from 0.4 to 3.5 ach (approximately 1.6 to 15 cfm per person). The laboratory study included only tests of memorization performance, and had results similar to those from the field study. However, in these studies, the ventilation rates per person at the lower air exchange rates were very low even for classrooms, e.g., less than 2 cfm per person. In addition, these studies intentionally did not disentangle the effects of ventilation and temperature. Temperatures were higher by approximately 4 °F in the low-ventilation conditions, as they would be in a building cooled by the outdoor air supply. Higher temperatures, in the temperature ranges encountered in this study, averaging 81.5 °F in the low ventilation condition, have been shown to reduce work performance [20]. Thus, these two studies do not provide information about how ventilation rates affect student performance when temperature is maintained constant, but the studies do indicate the combined effect of ventilation and temperature on school work.

As discussed in a later section, higher classroom ventilation rates have also been linked to a reduction in student absence, which, in turn, may improve student learning.

In summary, while the relevant research is not extensive, the available scientific literature indicates the potential for 5% to 10% increases in aspects of student performance and moderately higher pass rates in standardized math and reading tests with increased classroom ventilation rates. Ventilation rates in roughly half of U.S. public elementary school classrooms appear to be less than specified in codes [21-23]; thus, the opportunities for increasing student performance by increasing ventilation rates may be substantial.

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