V. Community and Urban Systems

The spatial arrangement of buildings in communities and urban

systems can play an important role in GHG reduction.

Higher density, more spatially

compact and mixed use developments offer the potential for significant reductions in GHG emissions

through three complementary effects:

  Reduced per unit area consumption of district energy for cooling, heating, and power generation; 

  Reduced municipal infrastructure requirements, including the reduced need for construction of

streets and electric, communication, water, and sewage lines, and other services; and

  Reduced VMT, including shorter freight and person trips, as well as the substitution of these

trips with public transit, walking, and cycling.

The achievement of significant reductions, however, will require a major change in the way U.S.

urban systems have been evolving over the past half century. The well documented post World War II

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flight to the suburbs by both households and businesses has created the phenomenon now known as

urban sprawl.

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Enabled and encouraged by the popularity of the private automobile, inexpensive gaso 

line, and an extensive high speed highway network expansion program, a key characteristic of sprawl has

been the emergence of large tracts of essentially single use land developments. This includes land given

over to detached single family homes, as well as large areas devoted to commercial strip developments

and multi store shopping centers. The resulting separation of trip origins and destinations has translated

to a significant increase in not only daily commuting distances, but also in the frequency as well as the

length of many vehicle based shopping and other personal service trips.

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Between 1969 and 2001, the

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average annual VMT per household increased from 12,400 to 21,500 (while average household size fell

from 3.2 to 2.6 persons, and the average number of vehicles per household grew from 1.2 to 1.9).

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Towards a Climate Friendly  

Built Environment

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