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The objective of this study was to investigate associations between indoor air quality (IAQ) in K-12 classrooms and student academic performance. During the academic years 2015–2017, various IAQ factors in 220 classrooms in the US were measured seasonally, excluding summer. Measurements were taken during occupied and unoccupied times in several classrooms within each school. Occupied measurements included indoor carbon dioxide (CO2) and formaldehyde concentrations, and fine and coarse particle counts. Unoccupied measurements consisted of ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and total volatile organic compounds (TVOCs) concentrations. Ventilation rates of classrooms were estimated using measured CO2 concentrations. In addition to IAQ data, classroom aggregated student achievement scores and demographic information were collected from participating school districts. Demographic data included percentage rates of free and reduced lunch recipients (PFRL), high-performance students (PGIF), and special education students (PSPED). A multivariate linear regression analysis was used to investigate the associations between IAQ factors and student scores using demographic data as controls. The results revealed associations between student scores and ventilation system type, ventilation rates, fine particle counts, and O3 and CO concentrations. This research provides valuable information to school districts and design engineers, enabling them to design school environments for improved student performance.
Adel Kabirikopaei; Josephine Lau; Jayden Nord; Jim Bovaird. Identifying the K-12 classrooms' indoor air quality factors that affect student academic performance. Science of The Total Environment 2021, 786, 147498 .
AMA StyleAdel Kabirikopaei, Josephine Lau, Jayden Nord, Jim Bovaird. Identifying the K-12 classrooms' indoor air quality factors that affect student academic performance. Science of The Total Environment. 2021; 786 ():147498.
Chicago/Turabian StyleAdel Kabirikopaei; Josephine Lau; Jayden Nord; Jim Bovaird. 2021. "Identifying the K-12 classrooms' indoor air quality factors that affect student academic performance." Science of The Total Environment 786, no. : 147498.
(1) The association of the indoor environmental conditions in classrooms with illness-related absenteeism (IRA) was not well investigated. In addition, studying the association between heating and non-heating seasons were very limited; (2) To fill this knowledge gap, a research team collected various indoor air quality (IAQ) and thermal comfort conditions (TC) of 85 elementary classrooms in two school districts from the Midwestern United States throughout an academic year; in total, 255 classroom visits were performed. A negative binomial regression model was implied to associate the classroom’s IAQ and TC with IRA, separating for heating and non-heating seasons; (3) During non-heating season, a 3% increase of IRA was estimated with 1,000,000-counts/L increase of particles that had a diameter less than 2.5 μm (PN2.5); during the heating season, a 3% increase of IRA were expected with 100 ppm increase of room averaged CO2 concentration; and (4) These results suggested that the IAQ and TC factors could associated with IRA differently between heating and non-heating seasons.
Shihan Deng; Bin Zou; Josephine Lau. The Adverse Associations of Classrooms’ Indoor Air Quality and Thermal Comfort Conditions on Students’ Illness Related Absenteeism between Heating and Non-Heating Seasons—A Pilot Study. International Journal of Environmental Research and Public Health 2021, 18, 1500 .
AMA StyleShihan Deng, Bin Zou, Josephine Lau. The Adverse Associations of Classrooms’ Indoor Air Quality and Thermal Comfort Conditions on Students’ Illness Related Absenteeism between Heating and Non-Heating Seasons—A Pilot Study. International Journal of Environmental Research and Public Health. 2021; 18 (4):1500.
Chicago/Turabian StyleShihan Deng; Bin Zou; Josephine Lau. 2021. "The Adverse Associations of Classrooms’ Indoor Air Quality and Thermal Comfort Conditions on Students’ Illness Related Absenteeism between Heating and Non-Heating Seasons—A Pilot Study." International Journal of Environmental Research and Public Health 18, no. 4: 1500.
Indoor air quality (IAQ) data of 220 classrooms in the Midwestern region of the US were measured during 2015–2017. During three seasons (fall, winter, and spring), indoor and outdoor CO2 concentrations of each classroom were measured under both occupied and unoccupied conditions. To calculate ventilation rates from the collected CO2 data, three main methods derived from the mass-balance equation were used: (1) steady-state; (2) decay rate; and (3) build-up. Since the uncertainty of the individual measurement parameter affects the accuracy or reliability of the calculated, an uncertainty analysis was performed for all three methods. The uncertainty of the estimated ventilation rates in relation to the volume of the classroom, indoor and outdoor CO2 levels, and estimated student CO2 emission rates were determined. The study shows that the steady-state method has the least uncertainty in ventilation rate calculations, while the decay and build-up methods had the lowest and highest values for ventilation rates, respectively. The results also show the estimated ventilation has a larger variance in single-zone systems than in multiple-zone systems. In field measurements, CO2 readings contribute to the largest portion of uncertainty for all three methods. Therefore, with CO2 as the tracer gas, improving the accuracy of CO2 measurement should receive the highest priority for study.
Adel Kabirikopaei; Josephine Lau. Uncertainty analysis of various CO2-Based tracer-gas methods for estimating seasonal ventilation rates in classrooms with different mechanical systems. Building and Environment 2020, 179, 107003 .
AMA StyleAdel Kabirikopaei, Josephine Lau. Uncertainty analysis of various CO2-Based tracer-gas methods for estimating seasonal ventilation rates in classrooms with different mechanical systems. Building and Environment. 2020; 179 ():107003.
Chicago/Turabian StyleAdel Kabirikopaei; Josephine Lau. 2020. "Uncertainty analysis of various CO2-Based tracer-gas methods for estimating seasonal ventilation rates in classrooms with different mechanical systems." Building and Environment 179, no. : 107003.
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. CO2 concentrations were acquired from each of the classrooms while simultaneously monitoring outdoor CO2 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 CO2 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.
Shihan Deng; Josephine Lau. Seasonal variations of indoor air quality and thermal conditions and their correlations in 220 classrooms in the Midwestern United States. Building and Environment 2019, 157, 79 -88.
AMA StyleShihan Deng, Josephine Lau. Seasonal variations of indoor air quality and thermal conditions and their correlations in 220 classrooms in the Midwestern United States. Building and Environment. 2019; 157 ():79-88.
Chicago/Turabian StyleShihan Deng; Josephine Lau. 2019. "Seasonal variations of indoor air quality and thermal conditions and their correlations in 220 classrooms in the Midwestern United States." Building and Environment 157, no. : 79-88.
Recently, the requirement to continuously collect bioaerosol samples using shorter response times has called for the use of real-time detection. The decreased cost of this technology makes it available for a wider application than military use, and makes it accessible to pharmaceutical and academic research. In this case study, real-time bioaerosol monitors (RBMs) were applied in elementary school classrooms—a densely occupied environment—along with upper-room ultraviolet germicidal irradiation (UVGI) devices. The classrooms were separated into a UVGI group and a non-UVGI control group. Fluorescent bioaerosol counts (FBCs) were monitored on 20 visiting days over a four-month period. The classroom with upper-room UVGI showed significantly lower concentrations of fine size (<3 μm) and total FBCs than the control classroom during 13 of the 20 visiting days. The results of the study indicate that the upper-room UVGI could be effective in reducing FBCs in the school environment, and RBMs may be applicable in reflecting the transient conditions of the classrooms due to the dynamic activity levels of the students and teachers.
Chunxiao Su; Josephine Lau; Fang Yu. A Case Study of Upper-Room UVGI in Densely-Occupied Elementary Classrooms by Real-Time Fluorescent Bioaerosol Measurements. International Journal of Environmental Research and Public Health 2017, 14, 51 .
AMA StyleChunxiao Su, Josephine Lau, Fang Yu. A Case Study of Upper-Room UVGI in Densely-Occupied Elementary Classrooms by Real-Time Fluorescent Bioaerosol Measurements. International Journal of Environmental Research and Public Health. 2017; 14 (1):51.
Chicago/Turabian StyleChunxiao Su; Josephine Lau; Fang Yu. 2017. "A Case Study of Upper-Room UVGI in Densely-Occupied Elementary Classrooms by Real-Time Fluorescent Bioaerosol Measurements." International Journal of Environmental Research and Public Health 14, no. 1: 51.
Josephine Lau; Lily M. Wang; Clarence Waters; James Bovaird. A need for evidence-based and multidisciplinary research to study the effects of the interaction of school environmental conditions on student achievement. Indoor and Built Environment 2016, 25, 869 -871.
AMA StyleJosephine Lau, Lily M. Wang, Clarence Waters, James Bovaird. A need for evidence-based and multidisciplinary research to study the effects of the interaction of school environmental conditions on student achievement. Indoor and Built Environment. 2016; 25 (6):869-871.
Chicago/Turabian StyleJosephine Lau; Lily M. Wang; Clarence Waters; James Bovaird. 2016. "A need for evidence-based and multidisciplinary research to study the effects of the interaction of school environmental conditions on student achievement." Indoor and Built Environment 25, no. 6: 869-871.
In the part 1 article, CO2-based Dynamic Reset (DR) was proposed and evaluated as an energy saving demand controlled ventilation (DCV) strategy by reducing the outdoor airflow (OA) rate when the occupancy is under design occupancy. Further energy saving potential still exists when the zone primary airflow rate is modulated or re-set instead of only reseting the outdoor airflow. Two new control strategies are presented and called as CO2-based DR with zone primary airflow setpoint reset (DR+ZDR) in this part 2 article. The system level of these control strategies is the same as CO2-based DR in part 1 article. The additional control features are added at the zone level. The zone primary airflow rate minimum setpoint will first be reset to increase system ventilation efficiency, which will lead to a reduced system OA rate. With this proposed DR+ZDR, the design minimum zone primary airflow rate can be designed lower than the regular setpoint used in variable air volume terminal box minumum setpoints. This new setting reduces the energy consumption for the system supply fan as well as energy consumption for terminal reheating. Both energy simulation and airflow simulation were conducted in different locations of a building. In this paper, the results show that the proposed strategies of CO2-based DR+ZDR consume less energy when compared to CO2-based DR presented in part 1 paper and the baseline case “without DCV”. The average annual system OA rates for two options of proposed DCV are 44.1% and 45%, respectively, less than the OA rate for “without DCV”. Therefore, the proposed DCV control strategies are suggested to be considered for CO2-based demand controlled ventilation for multiple zone single duct VAV systems with terminal reheat.
Xingbin Lin; Josephine Lau. Demand controlled ventilation for multiple zone HVAC systems—Part 2: CO 2 -based dynamic reset with zone primary airflow minimum setpoint reset (RP 1547). Science and Technology for the Built Environment 2015, 21, 1100 -1108.
AMA StyleXingbin Lin, Josephine Lau. Demand controlled ventilation for multiple zone HVAC systems—Part 2: CO 2 -based dynamic reset with zone primary airflow minimum setpoint reset (RP 1547). Science and Technology for the Built Environment. 2015; 21 (8):1100-1108.
Chicago/Turabian StyleXingbin Lin; Josephine Lau. 2015. "Demand controlled ventilation for multiple zone HVAC systems—Part 2: CO 2 -based dynamic reset with zone primary airflow minimum setpoint reset (RP 1547)." Science and Technology for the Built Environment 21, no. 8: 1100-1108.
Chunxiao Su; Josephine Lau; Shawn Gibbs. Evaluation of ultraviolet germicidal irradiation in reducing the airborne cultural bacteria concentrations in an elementary school in the Midwestern United States. Journal of environmental health 2015, 77, 1 .
AMA StyleChunxiao Su, Josephine Lau, Shawn Gibbs. Evaluation of ultraviolet germicidal irradiation in reducing the airborne cultural bacteria concentrations in an elementary school in the Midwestern United States. Journal of environmental health. 2015; 77 (9):1.
Chicago/Turabian StyleChunxiao Su; Josephine Lau; Shawn Gibbs. 2015. "Evaluation of ultraviolet germicidal irradiation in reducing the airborne cultural bacteria concentrations in an elementary school in the Midwestern United States." Journal of environmental health 77, no. 9: 1.
Upper room ultraviolet germicidal irradiance (UVGI) has been shown to reduce the concentration of bioaerosols in controlled chambers. However, there is a lack of experimental results on the reduction of bioaerosol concentrations by UVGI devices in actual uncontrolled buildings. This study was carried out in an American elementary school in the Midwest. Two sampling procedures were carried out in six selected classrooms with similar dimensions that were separated into two groups: (1) UVGI exposure group and (2) non-UVGI control group. Two-stage Tisch culturable impactors were utilized to collect airborne culturable bacteria and fungi. Monthly samples were collected during unoccupied period in sampling Procedure A and during close-to-occupied periods in sampling Procedure B. Student absenteeism data were collected. Nonparametric statistical methods were applied. Neither analysis of microorganisms nor student absenteeism showed a significant difference between the UVGI exposure and non-UVGI control groups in Procedure A. Analysis of the airborne culturable fine and total bacteria levels (1–8 µm) was significantly lower in the exposure classroom than those of the control classroom using Procedure B ( P values < 0.05). The result indicates that collecting airborne bacteria close to occupied time could be more effective in evaluating the performance of upper room UVGI. In this case study, upper room UVGI can reduce culturable bioaerosols in a crowed environment like classrooms.
Chunxiao Su; Josephine Lau; Shawn Gibbs. Student absenteeism and the comparisons of two sampling procedures for culturable bioaerosol measurement in classrooms with and without upper room ultraviolet germicidal irradiation devices. Indoor and Built Environment 2014, 25, 551 -562.
AMA StyleChunxiao Su, Josephine Lau, Shawn Gibbs. Student absenteeism and the comparisons of two sampling procedures for culturable bioaerosol measurement in classrooms with and without upper room ultraviolet germicidal irradiation devices. Indoor and Built Environment. 2014; 25 (3):551-562.
Chicago/Turabian StyleChunxiao Su; Josephine Lau; Shawn Gibbs. 2014. "Student absenteeism and the comparisons of two sampling procedures for culturable bioaerosol measurement in classrooms with and without upper room ultraviolet germicidal irradiation devices." Indoor and Built Environment 25, no. 3: 551-562.
Demand controlled ventilation (DCV) is used to reduce the system outdoor airflow (OA) when the occupancy of the system is under design occupancy. However, the new versions of ASHRAE Standard 62.1-2010 make DCV more difficult to implement for multiple zone HVAC systems. This article proposes a CO2-based and occupancy-sensor-based dynamic reset of OA rate for multiple zone HVAC systems (“CO2-based DR”). This control strategy uses bioeffluent load estimation with a steady-state assumption to calculate and dynamically reset the system OA rate minimum set-point by solving the multiple-zone system equations for current conditions. Building energy and airflow simulations were implemented to assess the energy performance and indoor air quality of this control strategy. The simulation results showed that the average annual system OA rate for CO2-based DR is 14.6% less than the OA rate for without DCV, in which case the system OA is always maintained as constant. The annual monetary saving as a percentage of the baseline case (without DCV) is between 0.3% and 11.0% for 16 climate zones in the United States.
Xingbin Lin; Josephine Lau. Demand controlled ventilation for multiple zone HVAC systems: CO 2 -based dynamic reset (RP 1547). HVAC&R Research 2014, 20, 875 -888.
AMA StyleXingbin Lin, Josephine Lau. Demand controlled ventilation for multiple zone HVAC systems: CO 2 -based dynamic reset (RP 1547). HVAC&R Research. 2014; 20 (8):875-888.
Chicago/Turabian StyleXingbin Lin; Josephine Lau. 2014. "Demand controlled ventilation for multiple zone HVAC systems: CO 2 -based dynamic reset (RP 1547)." HVAC&R Research 20, no. 8: 875-888.
Josephine Lau. CO2-Based Demand Controlled Ventilation for Variable Air Volume Systems Serving Multiple Zones. Indoor and Built Environment 2013, 22, 721 -723.
AMA StyleJosephine Lau. CO2-Based Demand Controlled Ventilation for Variable Air Volume Systems Serving Multiple Zones. Indoor and Built Environment. 2013; 22 (5):721-723.
Chicago/Turabian StyleJosephine Lau. 2013. "CO2-Based Demand Controlled Ventilation for Variable Air Volume Systems Serving Multiple Zones." Indoor and Built Environment 22, no. 5: 721-723.