{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/106478"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/106478","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Role of pavements in urban energetics","abstract":"The Urban Heat Island (UHI) is a sustained increase in temperature in urban areas as compared to adjacent rural areas. This effect is partially due to the replacement of vegetated surfaces with lower-albedo impervious surfaces (primarily made of asphalt and concrete) to make way for urban infrastructure, and partially due to the decreased wind speed in urban areas as a result of increased turbulent dissipation. The UHI effect can be studied at a variety of spatial and temporal scales. A bulk of the literature has focused on the traditional, mesoscale definition, which compares an urban area to an adjacent rural area. However, the heterogeneity of the UHI at smaller scales has received less attention. The present study considers the distribution of energy (and hence temperature) within a city, which can be described as the study of urban energetics. The term ’microscale UHI’ is adopted to highlight this difference and is studied in terms of differences in air temperature at 2 m height averaged over an hour of the day. To determine the contribution of pavements to the development of microscale UHI, two research aims were pursued: (a) the thermal and optical characterization of asphalt and concrete, and the factors that influence them; and (b) the development and validation of an urban climate model to determine the wind speed and air temperature in a sub-area of a city. Asphalt field cores were characterized by a Transient Plane Source (TPS) technique for thermal properties and a spectrophotometer for optical properties. A new bilinear aging albedo model was developed, which can be easily calibrated. Lab concrete specimens of varying proportions but fixed constituents were cast, and the optical and thermal properties were found to be most sensitive to the volume of paste (VP) and the ratio of fly ash to cementitious materials (FA/CM). Finally, to rapidly measure the albedo of pavements over a large road network, a new instrument called the Discrete SPectrAl RefleCtometer (D-SPARC) was developed, which could measure the albedo of pavements during any time of the day or night approximately four times faster than the current standard technique, with a reasonable error of 0.02-0.06. Next, to simulate the urban microclimate, two numerical models were developed and validated: a 1-D pavement thermal model, called the Illinois Thermal Analysis Program Finite Volume (ILLITHERM-FV); and a 3D Computational Fluid Dynamics (CFD) RANS-based urban canyon model. These models were first tested on a hypothetical urban environment (3 by 3 city block) using representative meteorological data from Chicago, IL, with an extrusion-exclusion technique being used to generate a high-quality hexahedral mesh of the city. The urban canyon model was implemented using the open-source solver OpenFOAM and run with the pavement model in uncoupled and coupled modes. Results from the uncoupled showed that while pavements with higher albedo and thermal diffusivity could mitigate UHI by up to 0.7°C, the extent of mitigation varied spatially, depending on the urban form and wind direction. Interior urban canyons, which are away from the boundaries of the city, had a higher UHI than ones closer to the boundary. The uncoupled model underestimated the UHI by 2 to 10% as compared to the coupled model but took approximately three times less time to compute. The uncoupled model was then used to perform a case study on the Power Ranch community in suburban Phoenix, AZ where significant meteorological data was available. Changing the existing aged asphalt pavements to typical concrete pavement had a negligible impact on the UHI, but a reflective pavement decreased the air temperature by 0.2-0.4°C. A combination of cool pavements, roofs, and walls (reflective surfaces) led to a significant decrease of 0.8-1.0°C. However, the heterogeneous land cover in the area limited the spatial extent to which these strategies were effective, indicating that careful modeling of individual urban areas is needed before selecting any cool pavement strategy.","abstract_html":"The Urban Heat Island (UHI) is a sustained increase in temperature in urban areas as compared to adjacent rural areas. This effect is partially due to the replacement of vegetated surfaces with lower-albedo impervious surfaces (primarily made of asphalt and concrete) to make way for urban infrastructure, and partially due to the decreased wind speed in urban areas as a result of increased turbulent dissipation. The UHI effect can be studied at a variety of spatial and temporal scales. A bulk of the literature has focused on the traditional, mesoscale definition, which compares an urban area to an adjacent rural area. However, the heterogeneity of the UHI at smaller scales has received less attention. The present study considers the distribution of energy (and hence temperature) within a city, which can be described as the study of urban energetics. The term ’microscale UHI’ is adopted to highlight this difference and is studied in terms of differences in air temperature at 2 m height averaged over an hour of the day. To determine the contribution of pavements to the development of microscale UHI, two research aims were pursued: (a) the thermal and optical characterization of asphalt and concrete, and the factors that influence them; and (b) the development and validation of an urban climate model to determine the wind speed and air temperature in a sub-area of a city. Asphalt field cores were characterized by a Transient Plane Source (TPS) technique for thermal properties and a spectrophotometer for optical properties. A new bilinear aging albedo model was developed, which can be easily calibrated. Lab concrete specimens of varying proportions but fixed constituents were cast, and the optical and thermal properties were found to be most sensitive to the volume of paste (VP) and the ratio of fly ash to cementitious materials (FA/CM). Finally, to rapidly measure the albedo of pavements over a large road network, a new instrument called the Discrete SPectrAl RefleCtometer (D-SPARC) was developed, which could measure the albedo of pavements during any time of the day or night approximately four times faster than the current standard technique, with a reasonable error of 0.02-0.06. Next, to simulate the urban microclimate, two numerical models were developed and validated: a 1-D pavement thermal model, called the Illinois Thermal Analysis Program Finite Volume (ILLITHERM-FV); and a 3D Computational Fluid Dynamics (CFD) RANS-based urban canyon model. These models were first tested on a hypothetical urban environment (3 by 3 city block) using representative meteorological data from Chicago, IL, with an extrusion-exclusion technique being used to generate a high-quality hexahedral mesh of the city. The urban canyon model was implemented using the open-source solver OpenFOAM and run with the pavement model in uncoupled and coupled modes. Results from the uncoupled showed that while pavements with higher albedo and thermal diffusivity could mitigate UHI by up to 0.7°C, the extent of mitigation varied spatially, depending on the urban form and wind direction. Interior urban canyons, which are away from the boundaries of the city, had a higher UHI than ones closer to the boundary. The uncoupled model underestimated the UHI by 2 to 10% as compared to the coupled model but took approximately three times less time to compute. The uncoupled model was then used to perform a case study on the Power Ranch community in suburban Phoenix, AZ where significant meteorological data was available. Changing the existing aged asphalt pavements to typical concrete pavement had a negligible impact on the UHI, but a reflective pavement decreased the air temperature by 0.2-0.4°C. A combination of cool pavements, roofs, and walls (reflective surfaces) led to a significant decrease of 0.8-1.0°C. However, the heterogeneous land cover in the area limited the spatial extent to which these strategies were effective, indicating that careful modeling of individual urban areas is needed before selecting any cool pavement strategy.","abstract_has_math":false,"creators":["Sen, Sushobhan"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Civil Engineering","degree_department":null,"school":null,"contributors":["Al-Qadi, Imad","Masud, Arif","Roesler, Jeffery","Gregory, Jeremy","Harvey, John"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-03-02T22:38:52Z","date_published":"2020-03-02T22:38:52Z","updated_at":"2026-07-22T22:24:47Z","subjects":["urban heat island","computational fluid dynamics","concrete","asphalt","thermal conductivity","heat capacity","thermal diffusivity","albedo","emissivity","canopy level UHI","air temperature","urban form","land cover heterogeneity","wind direction"],"languages":["en"],"rights":["Copyright 2019 Sushobhan Sen"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/106478","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Al-Qadi, Imad","Masud, Arif","Roesler, Jeffery","Gregory, Jeremy","Harvey, John"]},{"key":"dc:creator","label":"Author","values":["Sen, Sushobhan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-03-02T22:38:52Z","2022-03-03T10:15:13Z","2019-12-04","2019-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["urban heat island","computational fluid dynamics","concrete","asphalt","thermal conductivity","heat capacity","thermal diffusivity","albedo","emissivity","canopy level UHI","air temperature","urban form","land cover heterogeneity","wind direction"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Sushobhan Sen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/106478"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The Urban Heat Island (UHI) is a sustained increase in temperature in urban areas as compared to adjacent rural areas. This effect is partially due to the replacement of vegetated surfaces with lower-albedo impervious surfaces (primarily made of asphalt and concrete) to make way for urban infrastructure, and partially due to the decreased wind speed in urban areas as a result of increased turbulent dissipation. The UHI effect can be studied at a variety of spatial and temporal scales. A bulk of the literature has focused on the traditional, mesoscale definition, which compares an urban area to an adjacent rural area. However, the heterogeneity of the UHI at smaller scales has received less attention. The present study considers the distribution of energy (and hence temperature) within a city, which can be described as the study of urban energetics. The term ’microscale UHI’ is adopted to highlight this difference and is studied in terms of differences in air temperature at 2 m height averaged over an hour of the day. To determine the contribution of pavements to the development of microscale UHI, two research aims were pursued: (a) the thermal and optical characterization of asphalt and concrete, and the factors that influence them; and (b) the development and validation of an urban climate model to determine the wind speed and air temperature in a sub-area of a city. Asphalt field cores were characterized by a Transient Plane Source (TPS) technique for thermal properties and a spectrophotometer for optical properties. A new bilinear aging albedo model was developed, which can be easily calibrated. Lab concrete specimens of varying proportions but fixed constituents were cast, and the optical and thermal properties were found to be most sensitive to the volume of paste (VP) and the ratio of fly ash to cementitious materials (FA/CM). Finally, to rapidly measure the albedo of pavements over a large road network, a new instrument called the Discrete SPectrAl RefleCtometer (D-SPARC) was developed, which could measure the albedo of pavements during any time of the day or night approximately four times faster than the current standard technique, with a reasonable error of 0.02-0.06. Next, to simulate the urban microclimate, two numerical models were developed and validated: a 1-D pavement thermal model, called the Illinois Thermal Analysis Program Finite Volume (ILLITHERM-FV); and a 3D Computational Fluid Dynamics (CFD) RANS-based urban canyon model. These models were first tested on a hypothetical urban environment (3 by 3 city block) using representative meteorological data from Chicago, IL, with an extrusion-exclusion technique being used to generate a high-quality hexahedral mesh of the city. The urban canyon model was implemented using the open-source solver OpenFOAM and run with the pavement model in uncoupled and coupled modes. Results from the uncoupled showed that while pavements with higher albedo and thermal diffusivity could mitigate UHI by up to 0.7°C, the extent of mitigation varied spatially, depending on the urban form and wind direction. Interior urban canyons, which are away from the boundaries of the city, had a higher UHI than ones closer to the boundary. The uncoupled model underestimated the UHI by 2 to 10% as compared to the coupled model but took approximately three times less time to compute. The uncoupled model was then used to perform a case study on the Power Ranch community in suburban Phoenix, AZ where significant meteorological data was available. Changing the existing aged asphalt pavements to typical concrete pavement had a negligible impact on the UHI, but a reflective pavement decreased the air temperature by 0.2-0.4°C. A combination of cool pavements, roofs, and walls (reflective surfaces) led to a significant decrease of 0.8-1.0°C. However, the heterogeneous land cover in the area limited the spatial extent to which these strategies were effective, indicating that careful modeling of individual urban areas is needed before selecting any cool pavement strategy.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01","The student, Sushobhan Sen, accepted the attached license on 2019-12-03 at 14:48.","The student, Sushobhan Sen, submitted this Dissertation for approval on 2019-12-03 at 14:58.","This Dissertation was approved for publication on 2019-12-04 at 11:16.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14671 on 2020-02-28 at 17:37:16","Made available in DSpace on 2020-03-02T22:38:52Z (GMT). No. of bitstreams: 3 SEN-DISSERTATION-2019.pdf: 128527584 bytes, checksum: 95448a19b50a10e9bac064f0acfe31d1 (MD5) LICENSE.txt: 4210 bytes, checksum: 49bf49189ea3a2f4042effa4ba9d069d (MD5) PROQUEST_LICENSE.txt: 4556 bytes, checksum: 0eb9ccc4931be902514c6f7512c0bfca (MD5) Previous issue date: 2019-12-04","Embargo set by: Seth Robbins for item 114022 Lift date: 2022-03-02T22:39:04Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 114022 on 2022-03-03T10:15:13Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Role of pavements in urban energetics"]}]}],"canonical_facts":{"dc:contributor":["Al-Qadi, Imad","Masud, Arif","Roesler, Jeffery","Gregory, Jeremy","Harvey, John"],"dc:creator":["Sen, Sushobhan"],"dc:date":["2020-03-02T22:38:52Z","2022-03-03T10:15:13Z","2019-12-04","2019-12"],"dc:description":["The Urban Heat Island (UHI) is a sustained increase in temperature in urban areas as compared to adjacent rural areas. This effect is partially due to the replacement of vegetated surfaces with lower-albedo impervious surfaces (primarily made of asphalt and concrete) to make way for urban infrastructure, and partially due to the decreased wind speed in urban areas as a result of increased turbulent dissipation. The UHI effect can be studied at a variety of spatial and temporal scales. A bulk of the literature has focused on the traditional, mesoscale definition, which compares an urban area to an adjacent rural area. However, the heterogeneity of the UHI at smaller scales has received less attention. The present study considers the distribution of energy (and hence temperature) within a city, which can be described as the study of urban energetics. The term ’microscale UHI’ is adopted to highlight this difference and is studied in terms of differences in air temperature at 2 m height averaged over an hour of the day. To determine the contribution of pavements to the development of microscale UHI, two research aims were pursued: (a) the thermal and optical characterization of asphalt and concrete, and the factors that influence them; and (b) the development and validation of an urban climate model to determine the wind speed and air temperature in a sub-area of a city. Asphalt field cores were characterized by a Transient Plane Source (TPS) technique for thermal properties and a spectrophotometer for optical properties. A new bilinear aging albedo model was developed, which can be easily calibrated. Lab concrete specimens of varying proportions but fixed constituents were cast, and the optical and thermal properties were found to be most sensitive to the volume of paste (VP) and the ratio of fly ash to cementitious materials (FA/CM). Finally, to rapidly measure the albedo of pavements over a large road network, a new instrument called the Discrete SPectrAl RefleCtometer (D-SPARC) was developed, which could measure the albedo of pavements during any time of the day or night approximately four times faster than the current standard technique, with a reasonable error of 0.02-0.06. Next, to simulate the urban microclimate, two numerical models were developed and validated: a 1-D pavement thermal model, called the Illinois Thermal Analysis Program Finite Volume (ILLITHERM-FV); and a 3D Computational Fluid Dynamics (CFD) RANS-based urban canyon model. These models were first tested on a hypothetical urban environment (3 by 3 city block) using representative meteorological data from Chicago, IL, with an extrusion-exclusion technique being used to generate a high-quality hexahedral mesh of the city. The urban canyon model was implemented using the open-source solver OpenFOAM and run with the pavement model in uncoupled and coupled modes. Results from the uncoupled showed that while pavements with higher albedo and thermal diffusivity could mitigate UHI by up to 0.7°C, the extent of mitigation varied spatially, depending on the urban form and wind direction. Interior urban canyons, which are away from the boundaries of the city, had a higher UHI than ones closer to the boundary. The uncoupled model underestimated the UHI by 2 to 10% as compared to the coupled model but took approximately three times less time to compute. The uncoupled model was then used to perform a case study on the Power Ranch community in suburban Phoenix, AZ where significant meteorological data was available. Changing the existing aged asphalt pavements to typical concrete pavement had a negligible impact on the UHI, but a reflective pavement decreased the air temperature by 0.2-0.4°C. A combination of cool pavements, roofs, and walls (reflective surfaces) led to a significant decrease of 0.8-1.0°C. However, the heterogeneous land cover in the area limited the spatial extent to which these strategies were effective, indicating that careful modeling of individual urban areas is needed before selecting any cool pavement strategy.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01","The student, Sushobhan Sen, accepted the attached license on 2019-12-03 at 14:48.","The student, Sushobhan Sen, submitted this Dissertation for approval on 2019-12-03 at 14:58.","This Dissertation was approved for publication on 2019-12-04 at 11:16.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14671 on 2020-02-28 at 17:37:16","Made available in DSpace on 2020-03-02T22:38:52Z (GMT). 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