A. Estimates of GHG Reduction Potentials

Well planned compact growth consumes 45 percent less land and costs

25 percent less for roads, 20 percent less for utilities, and 5 percent less for

schools, than does sprawling growth.

121

One study found a direct relationship between the

number of dwellings per acre and the level of GHGs released. At a fairly common suburban density of four

homes per acre, CO

2

emissions per household were estimated to be 25 percent higher than in an urban

neighborhood with 20 homes per acre.

122

Figure 12 shows the hypothesized impact of residential density on

travel related CO

2

emissions.

123

Locational efficiency research by Holtzclaw and coauthors, based on detailed spatial data for the

San Francisco Bay Area, Los Angeles, and Chicago, found energy efficiency to be highly correlated with

per acre residential density,

Figure 12

with public transit service

How 

Residential Density  

Affects Travel Related

density within walking

CO

2

Emissions

distance of the house, with

35

household income, and

with household size.

124

They

30

+

concluded that differences in

25

density and access to public

transit are significant predic 

20

tors of per household vehicle

15

miles of travel. Burer and

 emissions per household (lbs/year)

2

coauthors show that higher

CO

10

0

20

40

60

80

100

residential and employment

Households/Residential Acre

densities, mixed land use, 

+

Source: Computed using the San Francisco League of Conservation Voters calculator,

http://www.sflcv.org/density/index.html.

and job housing balance are

associated with shorter trips

and lower automobile ownership and use.

125

The most recent set of U.S. based locational efficiency

studies project considerable potential for GHG reductions, with savings on the order of 10 percent of the

2001 level of GHGs produced in the United States suggested as possible within as few as 10 years.

126

40

+

Towards a Climate Friendly  

Built Environment