What Is LCA?

Life cycle assessment is a technique for compiling and evaluating the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle (ISO, 1997). Essentially, LCA is a procedure whereby the environmental burdens associated with a product system are measured and evaluated by quantifying energy, raw material usage and environmental releases over its expected life-cycle. While life cycle assessment has been around since the 1970s, it has only been since the early 1990s that international standards have been developed in an effort to harmonise the technique. There are two international standards specifically related to the application of LCA:

ISO 14040:2006 Environmental Management – Life Cycle Assessment – Principles and Framework,

ISO 14044:2006 Environmental Management – Life Cycle Assessment – Requirements and Guidelines

 

While completing an LCA involves numerous phases, the real underpinnings of any LCA is the life cycle inventory (LCI) data on which it is based (see Athena databases below). Inventory analysis is the physical accounting or tracking of elementary flows from nature (energy and raw materials) and flows back to nature (emissions to air, water and land).

The ISO standards mentioned above are defined in vague language and can be interpreted in various ways, which makes compliance with the standard difficult to gauge. In fact, there is a rather wide set of alternatives for completing an LCA and complying with the documentation requirements of the standards. During the development of our LCI databases our methodology has evolved and we have carefully assessed these methods relative to the standards and made specific efforts to comply with the terminology, concepts and underlying spirit defined by the standards. Moreover, we have strayed away from adopting some of the more controversial interpretation methods prevalent in LCA (e.g. weighting across impact categories to arrive at a single score for comparative assertions). Instead we have placed the onus on the user of our software to weigh the inventory data and category characterisation measures the Pavement LCA provides when making the ultimate decision about which design alternative best fits the goals of the project being considered.

 

The Difference Between LCA and LCI

LCA is a method for assessing the environmental performance of a service, process or product, including a highway, over its entire life cycle. Basic steps include goal and scope definition, inventory analysis, impact assessment, and interpretation. The life cycle inventory analysis (or LCI) involves detailed tracking of all the flows in and out of the system of interest, including raw resources or materials, energy by type, water, and emissions to air, water and land by specific substance. This kind of analysis can be extremely complex and may involve dozens of individual unit processes in a supply chain (e.g., the extraction of raw resources, various primary and secondary production processes, transportation, etc.) as well as hundreds of tracked substances.