EIO-LCA (Economic Input Output Life Cycle Assessment) is a input/output life cycle analysis tool produced by the Green Design Institute at Carnegie Mellon University. Certain EIO-LCA models (including a 2002 model of the US economy) are available free of charge via the Internet.
While EIO-LCA is a life cycle analysis tool, it operates very differently than "traditional", process LCAs (described above). While process LCAs are typically denominated in terms of mass, following the flows of materials through a supply chain and associated industrial processes, input-output LCAs are denominated in terms of dollars, following the flow of money through the economy. For example, when a consumer spends $20,000 on a car, some of that money flows the first-tier suppliers, makers of engines, tires, radios, etc. In turn, some of that money flows to second tier suppliers (the engine maker purchases steel, spark plugs, etc.). Some of that money flows to third tier suppliers (the steel maker purchases iron ore), and so on. Economic input-output data (typically drawn from the US Economic Census) mathematically portrays all of the inter-industry relationships that result from consumption. EIO-LCA combines this economic information with estimates of the emissions associated with production (emissions per dollar) in each of the different sectors of the economy,
EIO-LCA (and input/output LCA methods in general) offers two major advantages over process LCA: it is free, and it is fast. In addition, by including all emissions throughout the entire supply chain, it avoids the problem in process LCA of "cut-off errors", the exclusion of emissions from processes that are believed to contribute little to the total.
EIO-LCA only evaluates life-cycle emissions upstream, associated with manufacturing, resource extraction and supply chains. It does not evaluate the full life cycle emissions (including use and end-of-lfe) for any given product or material. As such, its applicability for informing recycling programs is limited. In contrast, EIO-LCA can offer some rough estimates of the GHG impacts associated with producing a variety of commodities, and by extension, the GHG benefits of not producing those commodities (resulting from waste prevention, reuse, or other "sustainable consumption" efforts). However, it is important to understand some of the limitations inherent in all input/output LCAs (including EIO-LCA). Major limitations include the following:
- Some sectors are exceptionally broad and reflect average conditions within that sector (commodity). For example, all fresh vegetables are classified in a single commodity sector, "vegetable and melon farming". EIO-LCA doesn't differentiate between potatoes and lettuce, or between organic and non-organic production. Similarly, EIO-LCA doesn't distinguish between paper products made with higher vs. lower levels of recycled content.
- Because input/output LCAs are denominated in dollars (or other currency), a doubling of consumption (expenses) in any single commodity category is assumed to translate into an equal doubling of impacts. This is clearly not the case for many commodities. For example, a $30,000 hybrid car will not necessarily have twice the GHG impacts (in manufacturing) compared to a $15,000 conventional car. Similarly, if a consumer is choosing an expensive but highly durable product over a less expensive but lower quality product, it would be important to compare products on the basis of life cycle costs (dollars spent not just to buy one durable vs. one low quality product, but rather dollars spent over a longer period of time, reflecting the greater number of purchases of the lower priced but lower quality product).
- EIO-LCA makes the simplifying assumption that all production and all supply chains are limited to the United States. As such, it likely undercounts (on average) GHG emissions.
Before using the EIO-LCA tool it is important to read the short documentation that explains how it is used. For example, EIO-LCA conducts all calculations on the basis of producer prices, not consumer prices. (Producer prices are what the producer of a commodity is paid. For example, while a consumer might pay $1 for a cookie, the producer might only be paid $0.55; the remainder ($0.45) going to post-production transportation, wholesale, and retail margins.) For additional information on EIO-LCA, visit the EIO-LCA website.