Environmental Engineering Reference
In-Depth Information
20.3.4.8 Ecological Footprint
The conceptual idea of an ecological footprint is that it is the area of productive
land and water ecosystems required to produce the resources consumed and assimi-
late the wastes produced (Chambers et al. 2007 ). The Department for Environment
Food and Rural Affairs ( 2007c ) states that it provides a measure of the extent to
which human activities exceed two specific environmental limits: the availabil-
ity of bioproductive land and the availability of forest areas to sequester carbon
dioxide emissions. It is derived from data from resource flow analysis, about a
range of activities such as transport, energy use, materials and product consump-
tion, waste production and water use. The impacts of these activities are converted
into a common currency, global hectares (gha). Using this common unit, a broad
range of impacts can be aggregated to derive ecological footprints for products,
processes, organisations, etc. The method does have limitations. It does not incor-
porate all aspects of ecological resources and services, and it excludes the use of
non-renewable resources. Related concepts are water footprints (Waterwise 2007 24 )
and waste footprints (Waste and Resources Action Programme 2007 ).
Like eco-efficiency, ecological footprint analysis focuses on environmental sus-
tainability issues, and perhaps not all aspects of environmental sustainability; for
example it does not consider the aesthetic value of landscapes, conservation and
Biodiversity issues or the built environment. Hence it is not really adequate as
a surrogate for sustainability appraisal, although it can inform certain aspects of
sustainability appraisal.
20.3.4.9 Energy Intensity/Efficiency
Energy intensity is a simple metric that can be used to compare processes such as
waste management processes, for example, kWh to treat a tonne of waste. Energy
intensity may also be an indicator of wider environmental effects, such as green-
house gas emissions and emissions of acidic gases. Energy efficiency has been
proposed as a means of comparing the overall environmental impact of remedia-
tion technologies by the European EURODEMO project (EURODEMO 2007a , b ).
Similar metrics are water intensity and carbon intensity (Nichols and Looney 2007 ).
These metrics can inform individual aspects of the environmental element of sus-
tainability appraisal, but do not offer a complete substitute. The use of renewable
energy complicates both energy intensity and carbon footprint assessments, and
individual tools need to be carefully scrutinised to determine whether benefits from
renewables are properly accounted for.
20.3.4.10 Risk Assessment
Risk Assessment is a way of evaluating the likelihood and magnitude of harm or
detriment caused by exposure of receptors to potential hazards, for example from
24 See also www.waterfootprint.org
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