LCA is a method for 'extended' impact assessment covering not just one location but a full production chain. It consists of inventory and evaluation of all environmental impacts over the entire life cycle of a product or service (micro level) or a larger slice of the economy (meso/macro level) such as 'transport fuels' or 'electricity generation'. An LCA starts with collecting all relevant data on resource extraction, processing, manufacturing, use and end-of-life treatment, including recycling, listing inputs (energy, materials,..) and outputs (emissions to air, water, waste,..) for each step. The next step is impact assessment, translating those inputs and outputs to a small number of issues that are known to be environmentally relevant such as climate change, smog formation and loss of biodiversity.

LCA can be used for assessment of a single function or for comparison of alternatives. If data is collected to be fully specific (primary data) and reporting ISO compliant, this is called full LCA . It requires considerable effort, but yields very precise results that pinpoint exactly where your product stands out from others or alternatives. If data is largely collected from generic sources (secondary data), this is called a scan LCA . It is quicker and cheaper and reveals environmental `hot spots' in the life cycle that your product stewardship or environmental management efforts may focus on. A scan LCA can be implemented in the form of a simple stand-alone tool (e.g. spreadsheet) that allows you to assess a range of products within the same framework. Environmental product declarations (EPD) require underlying LCA information. Water foot printing can be part of an assessment of several impacts are evaluated as a separate issue. One way of expressing LCA results is the ecological foot print , which is an indicator expressing one's footprint in terms of land area. However, there are many more ways of expressing LCA results and the choice of appropriate indicators is always part of the project.