Ambient monitoring and air quality modeling of air toxics concentrations at the neighborhood-scale level is a key element for human exposure and health risk assessments. Since 2005, The University of Texas at Austin (UT) has operated a dense ambient monitoring network that includes both hourly automated gas chromatographs as well as threshold triggered canister samples and meteorological data in the Corpus Christi area. Although Corpus Christi is in attainment with the National Ambient Air Quality Standards for both ozone and fine particulate matter, its significant petroleum refining complex has resulted in concerns about exposure to air toxics. The seven site network, incorporating both the industrial and residential areas in Corpus Christi, provided a unique opportunity to further the development and understanding of air quality modeling for toxic air pollutants at the neighborhood-scale level. Two air dispersion models, AERMOD and CALPUFF, were used to predict air concentrations of benzene for one of the UT operated monitoring sites (Oak Park monitoring site: C634) and the predictions were compared to the observed benzene concentration data at the Oak Park monitoring site to evaluate model performance. AERMOD and CALPUFF were also used to predict benzene concentrations in populated areas and at sensitive receptor locations such as schools and hospitals. Both AERMOD and CALPUFF were able to reproduce the early morning high benzene concentration and the northern wind effect except under strong NNE wind conditions, where the observed data indicated elevated high benzene concentration which AERMOD and CALPUFF failed to predict. These under-predictions could be due to the NNE strong wind condition at that time of these occurrences or could be attributed to different types of emissions other than the point sources emissions from the 2005 TCEQ Photochemical Modeling inventory, such as mobile sources or accidental emission events. These preliminary analyses could be expanded by modeling longer periods, by including other emission sources and by inter-comparisons with observed data from other CCNAT monitoring sites. In addition, fundamentally different modeling approaches (eulerian, rather than lagrangian) could be considered. / text

Previous research in the spatial assimilation of racial and ethnic groups has not assessed trends over time due to methodological difficulties and data limitations. I use an innovative method to assess the intercensal changes in neighborhood spatial attainment for African Americans, Hispanics, and non-Hispanic whites in Houston, Texas, between 1970 and 2000. I extend the current literature by showing that an accepted and commonly used method for assessing longitudinal change in spatial attainment is flawed and yields incorrect results. I highlight an alternative approach which makes use of data readily available in Census Summary Files to estimate individual-level spatial attainment regressions. I also show that the choice of neighborhood size affects estimates of spatial attainment effects. Although the influence of spatial scale has been demonstrated in the segregation literature, its consequences for spatial attainment research have not. I investigate and report findings from four geographic scales useful to and commonly used by spatial attainment researchers: the block group, the Census tract, the Zip Code Tabulated Area, and the Public Use Micro Data Area. I compare the benefits and drawbacks of estimating spatial attainment at each level of geography.

Ce travail est une contribution à l’évaluation environnementale des projets d’aménagements en phase amont de conception. Il porte plus spécifiquement sur l’intégration des questions de morphologie urbaine à l’analyse de cycle de vie (ACV) appliquée à l’environnement bâti à l’échelle du quartier. La performance énergétique des bâtiments est en partie conditionnée par les choix de conception en termes d’aménagement, et notamment par la forme urbaine (géométrie et types de surfaces) et ses interactions avec le climat. L’objectif de cette thèse est de proposer aux équipes de conception d’opérations d’aménagement un moyen de prendre en compte l’influence de la forme urbaine sur les potentiels énergétiques du quartier avec perspective cycle de vie.Une étude préalable a permis d’expliciter l’influence de la forme urbaine sur les potentiels énergétiques à l’échelle du quartier. Une approche de modélisation de l’énergie grise et de l’empreinte carbone des bâtiments est proposée, sur la base de laquelle une analyse de sensibilité à la forme urbaine et une analyse de contribution sont réalisées. Les résultats démontrent notamment l’influence primordiale de la forme des bâtiments ainsi qu’un lien très fort entre énergie grise et compacité du bâti. Une approche d’évaluation du potentiel de chauffage passif et du potentiel de confort d’été passif à l’échelle du quartier est également développée. Elle repose sur la réduction d’un quartier en quartier équivalent (réseau régulier de bâtiments parallélépipédiques), et sur l’application de métamodèles d’un moteur de simulation thermique. La méthode est testée est discutée sur un corpus de 45 cas d’étude. Ces développements méthodologiques ont vocation à être intégrés dans un outil existant d’ACV à l’échelle du quartier (NEST). / This work is a contribution to the environmental assessment of urban development projects in the upstream design phase. It focuses on integrating urban morphology issues with life cycle analysis (LCA) applied to the built environment at the neighborhood scale. The energy performance of buildings is partly determined by design choices relating to the urban form and its interactions with climate. The objective of this thesis is to provide to the design teams a way to take into account the influence of the urban form on the energy potentials of a neighborhood with a life cycle perspective.A preliminary study was conducted on two neighborhoods to detail the influence of the urban form on their energy potentials. An approach to modeling the embodied energy and embodied carbon of buildings is proposed. A sensitivity analysis and a contribution analysis of this model are performed on two generic building shapes. The results demonstrate the key influence of the shape of the buildings and a very strong link between the embodied energy and the building’s compactness. An approach to assessing the passive heating potential and passive summer comfort potential at the neighborhood scale is also developed. It is based on the transformation of a neighborhood in an equivalent urban form (regular array of block buildings), and on the application of metamodels of a thermal simulation engine. The method is tested and discussed on a corpus of 45 case studies. These methodological developments are intended to be integrated into an existing tool for neighborhood LCA (NEST).

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