R.
S. A. T. 
R.
S. A. T.
for Energy Management and Air Quality |
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Solar radiation heats the dark surfaces of streets and buildings. As urbanization expands, vegetation decreases. Combined, these two factors raise temperatures. The build-up of surface and air temperatures causes an increased demand on energy production for cooling. Increasing generating capacity for cooling energy involves significant increases in peak load production costs. Further, the need to increase generating capacity for cooling energy contributes to urban air pollution. Elevated urban temperatures accelerate the creation of smog through photochemical processes. These conditions result in increased illness and health care costs. |
According to the US Department of Energy one sixth of the electricity consumed in the United States goes to cooling buildings at an annual power cost of forty billion dollars. Mitigation strategies for the reduction of urban temperatures could save five to ten billion dollars in energy costs annually. Reductions in ozone and smog could save another five billion dollars in medical costs and lost work.
In Los Angeles, alone, the need for air conditioning could be lowered by 30%, or 1.74 billion kilowatt-hours, saving more than 170 million dollars per year in energy load reductions. The need for peak capacity could be lowered by 1,500 Megawatts; equivalent to two or three large power plants.
On top of the energy savings another 360 million
dollars could be saved in health care costs as a result of the
smog reduction. This brings the total savings in L.A. to more
than 1/2 Billion dollars annually.
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Within the urban setting some places are, of course, hotter than others. These sites should be identified and targeted for cooling in order of priority. Site identification can be precisely established using satellite imagery with color enhancement, showing various heat levels ranging from hot reds to cooler blues. Priority of sites is determined by cross-referencing in a GIS pertinent information such as land-cover type, surface temperature, albedo (reflectivity), energy demand data, ownership, zoning, relationship to surrounding surfaces, slope, aspect, and solar exposure. Urban land-cover information and surface albedo are generated from high resolution imagery. The one to five meter image data is used to separate urban land-cover into classes for emissivity, structure and vegetative index. A principal components analysis is performed on multispectral data to provide albedo levels. Surface temperatures are derived from LANDSAT's thermal band using a formula that combines the brightness-temperature measured at the satellite, the surface material's emissivity and the atmospheric conditions. The multiple remote sensing data sets are added to the local information within the GIS where the prioritization occurs. Once identified and prioritized, correcting overheated sites can be accomplished at considerably less cost than the consequent expenses in energy production and health care resulting from unrestrained thermal conditions. Using satellite thermal data for temperature analysis, along with high resolution visible and near to mid-infrared imagery for detailed land cover classification, Systems for World Surveillance provides services to identify optimal land-cover change for moderating urban temperatures. New surface coatings on roof tops and parking lots, shade tree plantings and increased vegetation, along with future urban designs incorporating greenways and forested areas will mitigate urban temperature extremes. Cities will become more comfortable to live in and their environments more sustainable while utility companies expand their customer base and increase their profits. |
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