Environmental Engineering Reference
In-Depth Information
The EF, as previously explained, translates consumption of various types
into a common metric—the total area of productive land and water ecosys-
tems required to produce the resources that the population consumes and to
assimilate the wastes that the population produces, wherever on Earth that
land and water may be located [85]. In calculating the footprint of nations or
regions, the different bioproductivities of various land types are taken into
account; this is achieved by incorporating equivalency factors, such that the
calculated EF is expressed as standardised acres of world-average productiv-
ity. EFs quantify humans' overall impact on nature in relation to carrying
capacity [86]. In 2000, the average global footprint was 6.25 acres per capita,
but there were only 4.8 acres available per person based on the biologically
productive area divided by the world population. Hence, we were in a deficit
of 1.45 acres per person [86], depleting Earth's natural capital rather than
living off nature's interest [87]. According to the Global Footprint Network
for 2007, these numbers are 6.7 acres per person as EF per capita worldwide,
while the biocapacity for Earth is only 4.4 acres per capita. Thus, the deficit
has increased to 2.3 acres [88].
The concept of an EF is now firmly ensconced in the environmental
literature and, despite its limitations [89-95], there is considerable sup-
port among researchers and environmentalists for the footprint as a clear,
unambiguous indicator of human impact on nature that is easily applied
[85,93,94,96].
One of the important linkages, that is not often drawn, is between EF,
urban density and transport energy. Some commentators have criticised the
use of per capita car use and per capita land use as confounding the statistics
because population is in both denominators [97,98]. However, if the popula-
tion factor is removed, then it is possible to look at whether land area (the
direct footprint of a city) relates to transport [84].
One inherent weakness of using the EF is that it, like other inventory
tools, is intended to measure impact. The EF is not designed look at cause
and effect. However, where qualitative data provide insight into decision-
making processes and choices, the EF becomes a useful tool for understand-
ing the pathways to different outcomes. Also, the raw data assembled for its
calculation could be used for specific questions of importance in planning
practice.
In addition, the EF could be used by policy makers as part of the approval
process for proposed developments. Rather than restricting development
according to standard urban design codes, developments could be clas-
sified by a maximum EF. It would be up to developers and designers to
plan communities that fall within the assigned EF. Rather than crippling
innovation and creativity in urban design through legislation, a maximum
assigned EF would foster new ideas and designs to tackle the sustainability
challenge [87].
A study on the EF in EcoVillage at Ithaca, New York (United States), found
that consumption, not built form, contributes most to the overall footprint;
