Sustainable Energy

What’s the difference?

In these times of climate change concern, individuals and organizations alike are eager for measurable criteria to compare the impact of products and services on global warming. The notions of ‘Life Cycle Assessment’, ‘Carbon Footprint’, and ‘Ecological Footprint’ often appear in the media, but their exact meaning and the differences between them are rarely explained or widely understood.

Calculating all the big environmental impact categories

Life Cycle Assessment (LCA) is the broadest indicator and an internationally standardized method (ISO 14040 and ISO 14044). It not only evaluates the impact on climate change, but also other impact categories such as acidification potential, eutrophication potential, ozone depletion potential, and ground level ozone creation. For each of these impact categories, the product or system is evaluated over its complete life span, from the extraction of raw material and manufacturing, to the use of the product by final consumers and end-of-life processes like recycling, energy recovery, and ultimate waste disposal.

The ISO standards provide robust and practice-proven requirements for performing transparent LCA calculations. Moreover, one can make use of extensive databases containing life cycle profiles of many goods and services, as well as many of the underlying materials, energy resources, transport systems, etc. Nevertheless, LCA calculations remain very complex and should therefore be applied only by professionals and preferably to a specific unit or application, such as a washing machine or a car tire.

Calculating the impact on climate change

A Carbon Footprint, also called Carbon Profile, is an LCA with the analysis limited to emissions that have an effect on climate change (carbon dioxide, methane, etc.). This limitation makes it easier to apply the calculation to integrated systems, such as an entire house or automobile.

Comparing with the amount of land needed

The Ecological Footprint of an activity tries to measure its consumption of natural resources and the amount of biologically productive land and sea needed to regenerate those resources and to absorb and render harmless the waste that is produced. While this measure is being increasingly used, it is not a scientific standard and is widely criticized. The translation of every impact into land and sea areas is neither self-evident nor is it easily established. Consequently, various methodologies are in use that sometimes give conflicting results. The calculations also largely depend on the prevailing technologies, meaning that their results are evolving with the state of technology. Nevertheless, being fully aware of its limitations, Ecological Footprint calculations can sometimes be used to establish a first rough approximation of the ecological impact of a product or a system.


  • Minute lecture ‘The Big 6 environmental impact categories’
  • Article ‘Carbon footprint – what is it and how to measure it’ on the JRC Web Site of the European Commission
  • Article ‘Ecological footprint’ on Wikipedia
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