Title

Determining Airflows and Volatile Organic Compound Source Strengths for an Occupied School

Date

8-11-2021 11:25 AM

Abstract

Volatile organic compounds (VOCs) are a group of air pollutants that can adversely impact human health, engage in chemistry indoors, and meaningfully degrade indoor and outdoor urban air quality. While extensive research with regard to VOC emission rates from indoor sources has been conducted, it was not until recently that this work began to focus on characterizing emissions from humans and human activity in depth. As buildings are constructed to be increasingly airtight, and the materials utilized are chosen to reduce VOC emissions, it follows that human contributions are poised to become increasingly important indoor sources of VOCs. Utilizing data extracted from a three-month campaign conducted at Harriet Tubman Middle School in Portland, Oregon—an institution built near a busy roadway—this study modeled airflows through the school and quantified source strengths for VOCs over the course of one week in May 2019. We developed an approach to estimate occupant density, outdoor air ventilation rates, and supply air flow rates through the school by analyzing the decay, steady-state, and accumulation periods of CO2 measured in return air. In total, emission rates for 249 compounds were calculated. Emission rates for seven compounds that are traditionally associated with human metabolism and activity became the study’s primary focus, as did source strengths for BTEX compounds (benzene, toluene, xylenes, and ethylbenzene), which are typically associated with traffic-related air pollution (TRAP). Calculated per-person emission rates for VOCs that are associated with human activity or metabolism, e.g., monoterpenes and isoprene, were consistent with estimates in the literature and indicate humans and their activities are an important indoor source of reactive VOCs. This study provides new data concerning VOC source strengths of indoor and outdoor origin to a building, which can enable the modeling of air pollution exposures in schools.

Biographies

Brett Stinson, Mechanical Engineering

Brett Stinson is majoring in mechanical engineering with a focus on fluid and thermal science. He is a research assistant in Dr. Elliott Gall’s Healthy Buildings Research Laboratory at Portland State University (PSU). He is currently a McNair, S-STEM, Green Building, and Ford Family Foundation scholar, vice president of PSU’s ASHRAE chapter, and SALP-recognized Student Leadership Fellow. He recently completed his Honors College thesis titled, Modeling Airflows and VOC Source Strengths for an Occupied School and has submitted work to the 2021 PSU Student Research Symposium, 2022 ASHRAE Winter Conference, and Indoor Chemistry 2021 conference. His research interests include indoor air quality, sustainable building design, and energy modeling. Brett is on track to complete his master’s degree in fluid and thermal science at Portland State University in Spring 2023, and then plans to pursue a Ph.D. Through his research in building science, he hopes to make the world a healthier, safer place for future generations.

Dr. Elliott Gall, Faculty Mentor, Department of Mechanical and Materials Engineering

Dr. Elliott Gall is an assistant professor at Portland State University (PSU) in the department of Mechanical and Materials Engineering. He received his B.S.E. in Environmental Engineering from the University of Florida and his Ph.D. in Civil Engineering from the University of Texas at Austin. At PSU, Dr. Gall leads the Healthy Buildings Research Laboratory, which aims to conduct fundamental and applied research exploring the many factors that impact our exposure to air pollution inside buildings, and an NSF-funded scholarship program on building science. He was acknowledged with the 2018 Yaglou Award from the International Society for Indoor Air Quality and Climate for his work on indoor ozone chemistry. Dr. Gall is active in professional societies, including ASHRAE and the International Society for Indoor Air Quality and Climate. His research at Portland State has been featured in national and local media, including The Atlantic, National Geographic, and The Seattle Times. He occasionally tweets about research and other topics @etgall.

Disciplines

Mechanical Engineering

Persistent Identifier

https://archives.pdx.edu/ds/psu/36191

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Aug 11th, 11:25 AM

Determining Airflows and Volatile Organic Compound Source Strengths for an Occupied School

Volatile organic compounds (VOCs) are a group of air pollutants that can adversely impact human health, engage in chemistry indoors, and meaningfully degrade indoor and outdoor urban air quality. While extensive research with regard to VOC emission rates from indoor sources has been conducted, it was not until recently that this work began to focus on characterizing emissions from humans and human activity in depth. As buildings are constructed to be increasingly airtight, and the materials utilized are chosen to reduce VOC emissions, it follows that human contributions are poised to become increasingly important indoor sources of VOCs. Utilizing data extracted from a three-month campaign conducted at Harriet Tubman Middle School in Portland, Oregon—an institution built near a busy roadway—this study modeled airflows through the school and quantified source strengths for VOCs over the course of one week in May 2019. We developed an approach to estimate occupant density, outdoor air ventilation rates, and supply air flow rates through the school by analyzing the decay, steady-state, and accumulation periods of CO2 measured in return air. In total, emission rates for 249 compounds were calculated. Emission rates for seven compounds that are traditionally associated with human metabolism and activity became the study’s primary focus, as did source strengths for BTEX compounds (benzene, toluene, xylenes, and ethylbenzene), which are typically associated with traffic-related air pollution (TRAP). Calculated per-person emission rates for VOCs that are associated with human activity or metabolism, e.g., monoterpenes and isoprene, were consistent with estimates in the literature and indicate humans and their activities are an important indoor source of reactive VOCs. This study provides new data concerning VOC source strengths of indoor and outdoor origin to a building, which can enable the modeling of air pollution exposures in schools.