Characterizing the fabric of the urban environment: A case studyof Metropolitan Chicago, Illinois and Executive Summary [report]

Hashem Akbari, Leanna Shea Rose
2001 unpublished
Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital
more » ... erial photographs for metropolitan Chicago covered a total of about 36 km2 (14 mi2). At 0.3m resolution, there were approximately 3.9 x 108 pixels of data. Four major land-use types were examined: commercial, industrial, residential, and transportation/communication. On average, for the areas studied, at ground level vegetation covers about 29 percent of the area (ranging 4 80 percent); roofs cover about 25 percent (ranging 8 41 percent), and paved surfaces about 33 percent (ranging 12 59 percent). For the most part, trees shade streets, parking lots, grass, and side-walks. In commercial areas, paved surfaces cover 50 60 percent of the area. In residential areas, on average, paved surfaces cover about 27 percent of the area. Land-use/landcover (LULC) data from the United States Geological Survey was used to extrapolate these results from neighborhood scales to metropolitan Chicago. In an area of roughly 2500 km2, defining most of metropolitan Chicago, over 53 percent is residential. The total roof area is about 680 km2, and the total paved surfaces (roads, parking areas, sidewalks) are about 880 km2. The total vegetated area is about 680 km2. Abstract Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semiautomatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for metropolitan Chicago covered a total of about 36 km 2 (14 mi 2 ). At 0.3m resolution, there were approximately 3.9 x 10 8 pixels of data. Four major land-use types were examined: commercial, industrial, residential, and transportation/communication. On average, for the areas studied, at ground level vegetation covers about 29% of the area (ranging 4-80%); roofs cover about 25% (ranging 8-41%), and paved surfaces about 33% (ranging 12-59%). For the most part, trees shade streets, parking lots, grass, and sidewalks. In commercial areas, paved surfaces cover 50-60% of the area. In residential areas, on average, paved surfaces cover about 27% of the area. Land-use/land-cover (LULC) data from the United States Geological Survey was used to extrapolate these results from neighborhood scales to metropolitan Chicago. In an area of roughly 2500 km 2 , defining most of metropolitan Chicago, over 53% is residential. The total roof area is about 680 km 2 , and the total paved surfaces (roads, parking areas, sidewalks) are about 880 km 2 . The total vegetated area is about 680 km 2 . 7 Executive Summary The Heat Island Reduction Initiative (HIRI) is a joint program sponsored by the U.S. Environmental Protection Agency (EPA) and the Department of Energy (DOE) to encourage the use of strategies designed to reduce demand for cooling-energy use and prevent smog formation. As part of the initiative, the Urban Heat Island Pilot Project (UHIPP) was launched to quantify the potential impacts of heat island reduction strategies in terms of energy savings, economic benefits, and airquality improvements. EPA selected five metropolitan areas of Sacramento, CA, Salt Lake City, UT, Chicago, IL, Houston, TX, and Baton Rouge, LA for the UHIPP study. Since the inception of the project, LBNL has conducted detailed studies to investigate the impact of mitigation technologies on heating and cooling energy use in these pilot cities. In addition, LBNL has collected urban surface characteristic data and conducted meteorology and urban smog simulations for the four pilot cities. One of the components of UHIPP research activities is to analyze the fabric of the pilot cities by accurately characterizing various surface components. This is important since the fabric of the city is directly relevant to the design and implementation of heat-island reduction strategies. Of particular importance is the characterization of the area fraction of various surface types as well as vegetative cover. Accurate characterization of the urban fabric would allow the design of implementation programs with a better assessment of the cost and benefits of program components. In addition, the results of such detailed analysis will be used in simulating the impact of heat-island reduction strategies on local meteorology and air quality.
doi:10.2172/900694 fatcat:sxsflohbgjagdimutg4dxc773u