To estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on meteorology and air quality of a city, it is essential to accurately characterize various urban surfaces. Of particular importance is the characterization of the area fraction of various surface-types, as well as the vegetative fraction. In this report, a method is discussed for developing data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color photography. We devised a semi-automatic Monte-Carlo method to sample the data and visually identifi the surface-type for each pixel. The color aerial photographs for Sacramento covered a total of about 65 square km (25 square mile). At 0.30-m resolution, there were approximately 7X108 pixels of data. Five major land-use types were examined: 1) downtctwn and city center, 2) industrial, 3) offices, 4) commercial, and 5) residential. In downtown Sacramento, the top view (above the canopy) shows that vegetation covers 30% of the area, whereas roofs cover 23% and paved surface (roads, parking areas, and sidewalks) 41%. Under-the-canopy fabric consists of 52% paved surfaces, 26% roofs, and 12% grass. In the industrial areas, vegetation covers 8-14% of the area, whereas roofs cover 19-23%, and paved surfaces cover 29-44%. The surface-type percentages in the office area were 21% trees, 16% roofs, and 49% paved surfaces. In commercial areas, vegetation covers 5-20%, roofs 19-20%, paved surfaces 4-4-68% (about 25-54% are parking areas). Residential areas exhibit a wide range of percentages of surface-types. On average, vegetation covers about 36% of the area (ranging 32-49%), roofs cover about 20% (ranging 12-25%), and paved surfaces about 28% (ranging 21-34%). Trees mostly shade streets, parking lots, grass, and sidewalks. Under the canopy the percentage of paved surfaces is significantly higher. In most non-residential areas, paved surfaces cover 50-70% of the area. In residential areas, on average, paved surfaces cover about 35% 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 Sacramento. In an area of roughly 800km2, defining most of metropolitan Sacramento, about half is residential. The total roof area is about 150km2 and the total paved surfaces (roads, parking areas, side walks) is about 310km2. The total vegetated area is about 230km2.

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Energy use and environmental parameters were monitored in three AT&T regeneration buildings during the summer of 2000. These buildings are constructed with concrete and are about 14.9 m 2 in size (160 ft 2 ; 10x16 ft). The buildings were initially monitored for about 1 1/2 months to establish a base condition. Then, the roofs of the buildings were painted with a white coating and the monitoring was continued. The original roof reflectances were about 26%; after the application of roof coatings the reflectivities increased to about 72%. ; at a cost of $0.1/kWh, savings are about $12.5 per year. Obviously, it costs significantly more than this amount to coat the roofs with reflective coating, particularly because of the remote locations of these buildings. However, since the prefabricated roofs are already painted green at the factory, painting them with white (reflective) color would bring no additional cost. Hence the payback time for having reflective roofs is nil, and the reflective roofs save an accumulated 3750 kWh over 30 years of the life of the roof.

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