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Copyright by Elliott Tyler Gall 2013 The Dissertation Committee for Elliott Tyler Gall Certifies that this is the approved version of the following dissertation: Ozone transport to and removal in porous materials with applications for low-energy indoor air purification Committee: Richard L. Corsi, Co-Supervisor Jeffrey A. Siegel, Co-Supervisor Kerry Cook Atila Novoselac Ying Xu Ozone transport to and removal in porous materials with applications for low-energy indoor air purification by Elliott Tyler Gall, B.S. ENV. E., M.S.E. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin May 2013 Dedication To Andrea, for her encouragement, support, and humor. Acknowledgements The research of this dissertation was conducted under the guidance of my two advisors, Drs. Jeffrey Siegel and Richard Corsi. I would like to thank them both for bringing me into the indoor air quality group at the University of Texas, and for their guidance, instruction, and feedback as mentors, teachers, and researchers. I would also like to acknowledge Drs. Atila Novoselac and Neil Crain for their discussions, suggestions, and instruction throughout my time at the University of Texas. Their impact on my research is immeasurable. The past and current members of the indoor air IGERT community and CEER research groups broadened my professional and personal horizons, and I want to particularly recognize Brent Stephens, James Lo, Ellison Carter, Matt Earnest, Elizabeth Walsh, Sonny Rosenthal, Erin Darling, Alix Broadfoot, and Tania de Souza. The UT EWRE program has made Austin, TX my home. Thanks in particular to Fernando Salas and Laura Read for the innumerable memories. James Seppi and Taylor Cook, James and Tara McDonald, Wil Sarchet, Tina Stanard, Paul Bireta, and David Rounce provided critical external support for the duration of this research. I would also like to thank my major funding sources, whose support made this research possible: the U.S. EPA STAR fellowship program, the NSF IGERT fellowship program, the Cockrell School of Engineering Thrust 2000 fellowship, and the ASHRAE Grant-in-Aid Award. Finally, I would like to acknowledge my family: my parents Rob and Lynn, my brothers Spencer and Greg (and Ted), Larry Pecan and Gia Marin, and my new family, the Ryans – thank you for all you do. v Ozone transport to and removal in porous materials with applications for low-energy indoor air purification Elliott Tyler Gall, Ph.D. The University of Texas at Austin, 2013 Supervisors: Richard L. Corsi and Jeffrey A. Siegel In the U.S. and other developed countries, humans spend the vast majority of their time within the built environment. As a result, a substantial portion of our collective exposure to airborne pollutants, even those of outdoor origin, occurs in indoor environments. In addition, building construction materials and operational practices are changing as we endeavor to reduce the energy burden of the built environment. These changes result in barriers and opportunities in mitigating exposure to indoor pollutants and the accompanying implications for human health. This dissertation advances knowledge regarding low-energy control of indoor ozone. Ozone is often considered a pollutant of outdoor concern. However, ozone in indoor environments presents important challenges regarding exposure, intake, and chemistry in the built environment. The investigations in this dissertation extend the state understanding of indoor transport and transformation of ozone, and the potential for using material- surface interactions in buildings to suppress concentrations of indoor ozone. The first objective relates to the determination of magnitudes of ozone removal and product emissions at room or building scales. This objective provides new data on reactive uptake and product generation in large-scale environments, develops Monte Carlo models vi describing indoor ozone removal by materials in homes, and compares active and passive methods of indoor ozone removal. The second objective addresses the need to develop improved air cleaning materials through experiments and modeling that address material- ozone reactions in porous materials. This objective advances the state of modeling heterogeneous reactive uptake of ozone by characterizing material physical properties and transport phenomena, determining their impact on ozone removal, and using these data to develop a more mechanistic model of material-ozone reactions. Ultimately, these investigations advance the engineering concepts that support the development of passive indoor pollutant controls, an important tool for reducing concentrations of indoor pollutants while supporting low-energy building initiatives. The combination of experimental characterization of ozone deposition velocities and product emission rates, whole-building Monte Carlo modeling, and mechanistic material/pollutant models provide important new data and approaches that expand the state of knowledge of the fate and transport of reactive pollutants in indoor environments. vii Table of Contents List of Tables in Summary of Methods and Research ........................................... xi List of Figures in Summary of Methods and Research......................................... xii Chapter 1: Introduction ............................................................................................1 1.1 Problem statement ............................................................................1 1.2 Objectives and scope of research .....................................................4 Chapter 2: Literature Review ...................................................................................8 2.1 Ozone sources, fate, and transport in indoor environments .............8 2.2 Indoor ozone chemistry ..................................................................13 2.2.1 Heterogeneous reactions at surfaces ..................................13 2.2.2 Secondary emissions following material/ozone reactions .18 2.2.3 Control of indoor ozone .....................................................19 2.2.4 Fundamental models of ozone transport and reaction .......21 Chapter 3. Summary of Methods and Research.....................................................27 3.1 Characterization of magnitudes of ozone removal and reaction product formation .....................................................................................27 3.1.1 Evaluation of several green building materials, comparison with small chamber results.................................................27 3.1.2 Determination of ozone removal effectiveness across homes with variable building stock parameters ............................38 3.1.3 Comparison of active and passive methods of indoor ozone control ................................................................................42 3.2. Development of fundamental representations of materials and more mechanistic models of reactive uptake of ozone. .......................49 3.2.1 Determination of fundamental physical material properties and their impact on reactive uptake of ozone to materials .......49 3.2.2 Development of more mechanistic models of reactive uptake of ozone to materials ..............................................................60 viii Chapter 4. Conclusions ..........................................................................................71 Appendix A ............................................................................................................76 Paper 1. Evaluation of several green building materials for ozone removal, primary and secondary emissions ...............................................................................77 Abstract .........................................................................................................77 Introduction ...................................................................................................78 Methodology .................................................................................................80 Results and Discussion .................................................................................90 Conclusions .................................................................................................102 Acknowledgements .....................................................................................103 Supplemental Information ..........................................................................104 Appendix B ..........................................................................................................110 Paper 2. Barriers and opportunities for passive removal of indoor ozone ...........111 Abstract .......................................................................................................111 Introduction .................................................................................................111 Mass Balance and Parameters .....................................................................113 Results and Discussion ...............................................................................115 Conclusions .................................................................................................122 Acknowledgements .....................................................................................123 Appendix C ..........................................................................................................124