As the building design and construction industry adopts a more holistic and comprehensive approach to assessing materials and resources for environmental impact, interest in life-cycle assessments (LCA) has risen and the market has become saturated with transparency documentation such as environmental product declarations (EPDs).

However, even a cursory review of an LCA study may yield a dizzying array of seemingly similar acronyms. Perhaps you have observed LCA, LCI, LCIA and LCC and wondered what the difference is between them. The following is a pared down summary of what each of these related acronyms refer to. 



Life-cycle assessment (LCA) is a procedure for quantifying the total environmental impact of a product or service across its entire lifetime. This multi-step process includes goal and scope definition, inventory analysis, impact assessment, and interpretation. LCAs are iterative by nature as the plausibility, quality, and completeness of pertinent information changes over time.



Life-cycle inventory (LCI) is the data-collection component of an LCA. Basically, an LCI endeavors to take an account of everything involved in the product or service. LCI considers the "system" at play by tracking all the inputs and outputs involved in making the product or service. The detailed accounting may include raw resources or materials, energy by type, water by source, and the various emissions to air, water, and/or land by substance. An LCI may be extremely complex, involving any number of individual unit processes contributing to relevant supply chains (e.g., the extraction of raw materials, various production processes, transportation, etc.) along with any/all constituent substances (for which there could be hundreds).



A life-cycle impact assessment (LCIA) could be thought of as a "what does it mean" step in the process. 

Through an LCIA, the data from the LCI is analyzed for environmental impact. The results are typically reported based on one of several standardized methods for categorizing and characterizing the life-cycle impact of the material/resource flows to and from the environment. 

There are several three widely recognized methods for conducting an LCIA, but two of the most common methods utilized for building products today are CML and TRACI.

The CML methodology, developed by the Institute of Environmental Sciences at the University of Leiden in the Netherlands, is the most widely used and often considered the most complete of the LCIA methodologies. It uses primarily European data to derive its environmental impact factors. It groups the LCI results into midpoint categories, according to themes. These themes are common mechanisms (e.g., climate change) or groupings (e.g., ecotoxicity).

The TRACI, or “Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts," methodology is an impact assessment methodology developed by the U.S. Environmental Protection Agency. Consistent with other LCIA methodologies, TRACI is primarily a midpoint approach. It differs from the CML methodology in that the data comes primarily from North American sources. However, the TRACI methodology is not as comprehensive or complete as the CML method.

Always observe the LCIA method being implemented. Based on the method, LCIA results may vary and this can complicate the comparability of different LCA studies. There are other variables that can affect the comparability too, including the system boundary (i.e., how far and deep does the analysis go), the function unit (i.e., the exact volume/mass/purpose of the item being assessed), and other specifics regarding the method. As a result, oftentimes two seemingly similar LCA studies may not actually be comparable in an "apples-to-apples" sense. 



Life-cycle costing (LCC) is another life-cycle approach through which the direct monetary costs involved with a product or service are examined rather than the environmental impact.