ZEMCH 2019 International Conference Proceedings April.2020 | Page 168
3. Results and Discussion
3.1. Environmental Parameters
Table 2 lists the maximum, minimum, mean, and standard deviation for each data item collected
at the time when the TSV surveys were taken. The range of indoor air temperature was 19.72~27.72℃,
and the range of mean radiant temperature was 20.17~28.04 ℃ . On the bias between indoor air
temperature and average radiant temperature, the mean was ‐0.4, and the standard deviation was 0.16,
indicating there was little difference between the two. The range of indoor relative humidity was
24.81~61.30%, satisfying comfort humidity range of 30~60% set by EPA for 90% of the time. The range
of carbon dioxide concentration was 532~4,328 ppm, averaging at 2,042 ppm. For 85% of the time, it
surpassed the adequate indoor carbon dioxide level of 1,000 ppm.
Table 2. Indoor Environmental Parameters
Parameters
Maximum
Minimum
Average
St.deviation
Mean radiant
28.04
20.17
24.29
1.61
temperature (℃)
Indoor air
27.72
19.72
23.89
1.65
temperature (℃)
Indoor relative
61.30
24.80
41.45
9.24
humidity (%)
CO₂
4328
532
2042
1034
(ppm)
Figure 2 displays the average occupancy schedule for the non‐exam period and the exam period.
For both periods, the number of occupants increased until 8 PM and started to decrease afterward, but
the difference in occupant density was significant. While the maximum occupant density during non‐
exam periods was no higher than 25%, that during exam periods reached up to 65%. As can be seen in
Figure 3, this brought about a difference in the fluctuation of carbon dioxide concentration. The figure
shows that the carbon dioxide concentration and the occupancy schedule also follow a similar form,
and the carbon dioxide concentration during the exam period is higher than the density during the
non‐exam period. In the non‐exam period, the average carbon dioxide concentration did not surpass
1,500ppm, but it showed an average of 2,258 ppm during exam periods, reaching over 4,000ppm
between 8 PM and 10 PM. This is higher than the recommended level of 1,000ppm by a large margin,
and it may cause students to feel suffocated and lower their concentration.
Figure 2. Hourly Average Occupancy
Figure 3. Hourly Average CO₂ Concentration
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ZEMCH 2019 International Conference l Seoul, Korea