Seasonal variations of indoor air quality and thermal conditions and their correlations in 220 classrooms in the Midwestern United States

Shihan Deng, Josephine Lau

Research output: Contribution to journalArticle

Abstract

In this 2-year, seasonally-repeated study, the research team surveyed the baseline conditions of indoor air quality (IAQ)and thermal conditions (TC)of 220 classrooms in the Midwestern region (Nebraska and Iowa)of the United States of America. Seasonal variations of each IAQ and TC variable and correlations between variables were also examined. CO 2 concentrations were acquired from each of the classrooms while simultaneously monitoring outdoor CO 2 concentration, particle counts, formaldehyde concentration, air temperature, globe temperature, and relative humidity. Ventilation rate and absolute humidity level were also estimated. The results showed the mean CO 2 concentration of 220 classrooms during the occupied hours throughout the measured seasons was 1171 ppm. The average ventilation rate was 5.6 L/s-person, below the suggested value by ASHRAE Std 62.1. Other IAQ and TC variables were found to be well-maintained when compared to the NIOSH or EPA standards. Large seasonal variations were found in humidity level, ventilation rate, particle counts, and formaldehyde concentration. It is therefore suggested that the monitoring of classroom IAQ and TC should be done periodically across the whole school year to comprehensively describe the conditions. There were significant correlations between IAQ and TC variables, which suggest relationships between these variables. This study revealed the baseline conditions and examined the seasonal variations of the classroom IAQ and TC of the region for the first time. Further benefits, such as improvement of classroom IAQ and TC, may result from this study.

Original languageEnglish (US)
Pages (from-to)79-88
Number of pages10
JournalBuilding and Environment
Volume157
DOIs
StatePublished - Jun 15 2019

Fingerprint

seasonal variation
indoor air
Air quality
air quality
air
classroom
Ventilation
ventilation
baseline conditions
Atmospheric humidity
formaldehyde
Formaldehyde
humidity
monitoring
Monitoring
Hot Temperature
relative humidity
air temperature
Temperature
human being

Keywords

  • Classroom
  • Formaldehyde
  • Midwestern United States
  • Seasonal variation
  • Ventilation rate

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Building and Construction

Cite this

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title = "Seasonal variations of indoor air quality and thermal conditions and their correlations in 220 classrooms in the Midwestern United States",
abstract = "In this 2-year, seasonally-repeated study, the research team surveyed the baseline conditions of indoor air quality (IAQ)and thermal conditions (TC)of 220 classrooms in the Midwestern region (Nebraska and Iowa)of the United States of America. Seasonal variations of each IAQ and TC variable and correlations between variables were also examined. CO 2 concentrations were acquired from each of the classrooms while simultaneously monitoring outdoor CO 2 concentration, particle counts, formaldehyde concentration, air temperature, globe temperature, and relative humidity. Ventilation rate and absolute humidity level were also estimated. The results showed the mean CO 2 concentration of 220 classrooms during the occupied hours throughout the measured seasons was 1171 ppm. The average ventilation rate was 5.6 L/s-person, below the suggested value by ASHRAE Std 62.1. Other IAQ and TC variables were found to be well-maintained when compared to the NIOSH or EPA standards. Large seasonal variations were found in humidity level, ventilation rate, particle counts, and formaldehyde concentration. It is therefore suggested that the monitoring of classroom IAQ and TC should be done periodically across the whole school year to comprehensively describe the conditions. There were significant correlations between IAQ and TC variables, which suggest relationships between these variables. This study revealed the baseline conditions and examined the seasonal variations of the classroom IAQ and TC of the region for the first time. Further benefits, such as improvement of classroom IAQ and TC, may result from this study.",
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AU - Lau, Josephine

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N2 - In this 2-year, seasonally-repeated study, the research team surveyed the baseline conditions of indoor air quality (IAQ)and thermal conditions (TC)of 220 classrooms in the Midwestern region (Nebraska and Iowa)of the United States of America. Seasonal variations of each IAQ and TC variable and correlations between variables were also examined. CO 2 concentrations were acquired from each of the classrooms while simultaneously monitoring outdoor CO 2 concentration, particle counts, formaldehyde concentration, air temperature, globe temperature, and relative humidity. Ventilation rate and absolute humidity level were also estimated. The results showed the mean CO 2 concentration of 220 classrooms during the occupied hours throughout the measured seasons was 1171 ppm. The average ventilation rate was 5.6 L/s-person, below the suggested value by ASHRAE Std 62.1. Other IAQ and TC variables were found to be well-maintained when compared to the NIOSH or EPA standards. Large seasonal variations were found in humidity level, ventilation rate, particle counts, and formaldehyde concentration. It is therefore suggested that the monitoring of classroom IAQ and TC should be done periodically across the whole school year to comprehensively describe the conditions. There were significant correlations between IAQ and TC variables, which suggest relationships between these variables. This study revealed the baseline conditions and examined the seasonal variations of the classroom IAQ and TC of the region for the first time. Further benefits, such as improvement of classroom IAQ and TC, may result from this study.

AB - In this 2-year, seasonally-repeated study, the research team surveyed the baseline conditions of indoor air quality (IAQ)and thermal conditions (TC)of 220 classrooms in the Midwestern region (Nebraska and Iowa)of the United States of America. Seasonal variations of each IAQ and TC variable and correlations between variables were also examined. CO 2 concentrations were acquired from each of the classrooms while simultaneously monitoring outdoor CO 2 concentration, particle counts, formaldehyde concentration, air temperature, globe temperature, and relative humidity. Ventilation rate and absolute humidity level were also estimated. The results showed the mean CO 2 concentration of 220 classrooms during the occupied hours throughout the measured seasons was 1171 ppm. The average ventilation rate was 5.6 L/s-person, below the suggested value by ASHRAE Std 62.1. Other IAQ and TC variables were found to be well-maintained when compared to the NIOSH or EPA standards. Large seasonal variations were found in humidity level, ventilation rate, particle counts, and formaldehyde concentration. It is therefore suggested that the monitoring of classroom IAQ and TC should be done periodically across the whole school year to comprehensively describe the conditions. There were significant correlations between IAQ and TC variables, which suggest relationships between these variables. This study revealed the baseline conditions and examined the seasonal variations of the classroom IAQ and TC of the region for the first time. Further benefits, such as improvement of classroom IAQ and TC, may result from this study.

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