What is Life Cycle Assessment?
Definition and objectives
The International Organization for Standardization (ISO) defines life cycle assessment (LCA) as the following:
"Compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle" (ISO 14040: 1997).
Among the tools that life cycle management (LCM) offers, LCA, or environmental balance, is one of the most comprehensive and high-performance methods. Life cycle assessment is the only method that assesses the environmental impacts of a product or activity (a system of products) over its entire life cycle. It is therefore a holistic approach that takes into account:
The main goal of the method is to lessen the environmental impacts of products and services by guiding the decision-making process. For companies, designers, and governments, life cycle assessment represents a decision-making aid tool for implementing sustainable development.
Regulated by the ISO 14040 series standards, LCA consists in four distinct phases:
The following figure illustrates the life cycle assessment framework as described by ISO. As shown in the figure, life cycle assessment is an iterative process. The choices made during the course of the study can be modified following new information.
LCA framework according to ISO
Due to time and cost constraints, variants of the LCA method have been formulated according to the guideline principles established by the Society of Environmental Toxicology and Chemistry (SETAC). For example, the boundaries of a system can be limited to certain life cycle stages or to certain impact categories or limited to the main contributors, identified according to expert opinion and experience.
The analysis can also be performed in a strictly qualitative fashion or using « secondary » data only (generic data from the literature or from databases). Such simplifications can affect the accuracy and applicability of life cycle assessment results, but can nevertheless allow for the identification of potential impacts and, to a certain extent, their assessment.
Life cycle assessment has become an important tool for the environmental impact assessment of products and materials and businesses are increasingly relying on it for their decision-making. The information obtained from an life cycle assessment can also influence environmental policies and regulations.
In practice, LCAs are mainly used for (Labouze et al., 1996):
Environmental systems comparison
Life cycle assessment is used for comparing on an environmental basis:
Manufacturing (as a improvement lever for the manufacturing phase)
Life cycle assessment can be employed with the aim of finding the most ecological way to improve product manufacturing. Consequently, it can be useful as a decision-making tool for new product development, as a guide for the optimization of energy and raw material consumption as well as for the identification of solutions in emission reduction and possible substitution of harmful substances.
Life cycle assessment can also be used for commercial development:
A significant number of life cycle assessment studies, European for the most part, have already been conducted on several different subjects. The following list is not exhaustive:
Strengths and limitations
Life cycle assessment (LCA) is a tool which offers many advantages:
LCA has however certain limitations:
Introduction to Life Cycle Assessment (LCA)
For more information about LCA
 ISO 14040:1997, Environmental Management: Life Cycle Assessment– Principles and framework, International Organisation for Standardization.
 ISO 14040:1997, Goal and Scope; ISO14041 (1998), Life Cycle Inventory Analysis; ISO14042 (2000), Life Cycle Impact Assessment; ISO14043 (2000), Life Cycle Interpretation; ISO14048 (2002), Environmental Management: Life Cycle Assessment – Data documentation format, International Organization for Standardization.