In this study, thermal performance evaluation of a selected region in Alton, Illinois is performed for two scenarios; one with all roofs covered with plants (green roofs), and the other one with conventional shingle roofs. Data for both roof structures comes from a prior experimental study that was conducted at Southern Illinois University Edwardsville. The purpose of this study is to use the obtained data and pertinent theory to determine thermal performance of buildings in a given region with the purpose of focusing on urban sustainability in residential areas. Roof systems that are considered are at three slope angles: 1°, 20°, and 40°. Thermal data from this experimental analysis is used to estimate the difference in total cooling load in buildings for the selected region. Image processing technique was used to determine the total roof area in the pilot region. To better understand the convective heat transfer over the rooftops due to wind flow, roof-wind interactions were also studied numerically using ANSYS software. Results showed that a residential green roof system can yield significant energy savings due to enhanced thermal insulation. This would lead to a noticeable reduction in carbon footprints for urban areas, contributing to a more sustainable environment.