The professional society for life cycle assessment

What is LCA?








Life Cycle Assessment (LCA) is the science of measuring the environmental impact of products and services over their entire life cycle from cradle to grave. A Life Cycle Assessment model is actually at least three different models.


  1. technosphere input-output models that describes the human activities in extracting, modifying, discarding and using energy and materials
  2. An emissions and resource model that estimates resource degradation and pollution emissions linked to the technosphere model, for example the emissions of air pollutants from burning a certain amount of fossil fuel in a boiler
  3. An environmental impact model that uses the resource and emission model outputs to estimate the impacts on the environment and the economy. The classic example is that of global climate change which is modeled in accordance with the work of the Intergovernmental Panel on Climate Change, yielding units of CO2 equivalents. 

All of these outputs of these models are expressed relevant to the functional unit of the product in question, for example covering a square meter of floor for 30 years, or delivering 1 kWh of energy to the point of use. The use of a functional unit is what allows LCAs to provide the environmental results to the user in terms that are relevant to the user.

A carbon footprint is a kind of LCA that only reports Climate Change impacts. Normally LCA covers all relevant impact categories, and it is therefore known as the holistic yardstick of environmental performance. Life Cycle impact assessment results are indicators of impacts, not measurements of actual impacts on the environment. For example, LCA does not measure the loss of particular ecosystems. Rather the LCA provides indicators of aggregate losses all ecosystems across the life cycle.

Life Cycle Assessment

Beginner's Resources

LCA for Mere Mortals

is a primer for those with no experience in LCA

LCA's EPDs and PCRs

A set of webinars was given in October 2009, in partnership with EPA Region 10. They are available for viewing as either the PDF or as the video version

Introduction to Life Cycle Assessment Scoping and Inventory

PDF file


Life Cycle Impact Assessment and Interpretation

PDF File