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164 • Green Project Management

ing into the Gantt chart for your project without first understanding the
objectives and having a charter.
The EPA defines this phase as follows: the impact assessment “is the
evaluation of potential human health and environmental impacts of the
environmental resources and releases identified during the LCI.” Impact
assessment should address ecological and human health effects; it should
also address resource depletion. Life cycle impact assessment (LCIA) dif-
fers from a traditional or “classical” risk assessment. The focus given to
risk assessment is a logical one considering it is the bread and butter of the
EPA and is a well-established approach to evaluating pollutant and site-
specific risk to human health and the environment.
While risk assessment modeling is at the ground level, impact model-
ing for LCIA is at a higher level of aggregation. For example, emissions
of 24,200 pounds of CO and 6.26 pounds of methane would be modeled
2
as follows:

CO GWP (global warming potential) impact factor value = 1
2

Methane GWP impact factor value = 21

(i.e., methane is 21 times more potent than CO as a global warmer)
2
CO GWP = 24,200 lb × 0.454 kg/lb × 1 = 10,900 kg CO -eq
2
2
Methane GWP = 6.26 lb × 0.454 kg/lb × 23 = 65.4 kg CO -eq
2
If CO and methane are the only contributors to GWP, then
2
Total GWP = 10,965 CO -eq
2

This type of calculation is applied for each impact category. Each life cycle
stage as well as the entire life cycle is modeled.
The steps of an LCI, per the EPA, are as follows:

1. Selection and Definition of Impact Categories: identifying relevant
environmental impact categories (e.g., global warming, acidification,
terrestrial toxicity) (see Table 9.3)
2. Classification: assigning LCI results to the impact categories (e.g.,
classifying carbon dioxide emissions to global warming)