Life cycle assessment, or LCA, is the investigation and evaluation of the
environmental impacts of a product, process or service. LCA evaluates all stages
of a productís life and considers each stage interdependently. Figure 1 provides
a schematic of a typical product manufacturing process. Inputs include raw
materials and energy. Life cycle stages include raw material acquisition,
manufacturing, product use, and finally, recycling or waste management. The
outputs, many of which impact the environment negatively, include atmospheric
emissions, waterborne wastes, solid wastes, co products and other releases.
Figure 1: Life cycle stages, inputs and outputs for life cycle assessment
(adapted from the U.S. Environmental Protection Agency (EPA)).
LCA is the most comprehensive approach to determining the environmental life
cycle impacts of a product and can be used as a tool to make decisions that
could result in lower environmental impacts. Per the International Organization
for Standards (ISO) 14040 and 14044,
LCA is conducted in four distinct phases:
Goal Definition and Scoping
- Define and describe the product, process or activity being analyzed.
- Identify and quantify energy, water and materials use and environmental
releases. Environmental releases may be solid waste, air emissions and waste
Impact Assessment- Assess the
potential human and ecological effects of energy, water and material usage, and
the environmental releases identified in the inventory analysis.
Interpretation- Evaluate the
results and select the preferred product or process.
The first phase,
Goal Definition and Scoping, is relatively simple since
one can generally identify and define the product or process being analyzed. The
second phase, Inventory Analysis, often called life cycle inventory
(LCI), is more difficult since one must have the capability to measure and
account for all inputs and outputs from a particular product or process. In many
cases, it is relatively easy to measure the inputs to a product or process but
it becomes much more difficult and expensive to measure environmental releases
or outputs. The third phase, Impact Assessment, is the most complex phase of an LCA.
In this phase, one attempts to equate the environmental releases identified in
the Inventory Analysis phase to their potential human and ecological
effects. The U.S. Environmental Protection Agency (EPA) developed the
Tool for the Reduction and Assessment of Chemical and
Other Environmental Impacts (TRACI) that allows for the examination of
the potential for impacts associated with the raw material usage and chemical
releases resulting from the processes involved in producing a product.
Figure 2 provides a schematic representation of potential environmental impacts
and one possible interpretation of their relative importance for the purposes of
identifying the most critical impacts. The relative importance of each impact
might change depending on the product or process being analyzed or on other
factors such as location and/or political influences. For example, many
governments have declared climate change or global warming potential as todayís
most important environmental impact.
Figure 2: Environmental impacts and relative importance of impacts (adapted from
United States Green Building Council (USGBC)).
the basis by which an Environmental Product Declaration (EPD)
are developed. EPDs are third party
verified (certified) reports published by product manufacturers that provide
quality assured and comparable information regarding environmental performance
of their product. The EPD basically reports the LCA results in a uniform