developers and investors a fair idea of the environmental impact of a specific chunk of investment in a particular sector. The model captures all the various manufacturing, transportation, mining and related requirements to produce a product or service. There are about 500 sectors in the EIOLCA model, with data sources on economic impacts, electricity use, fuel & ore use, fertilizer use, pollutant emissions, greenhouse gas emissions, toxic releases, external costs, water use, safety data and employment data (Hendrickson, Horvath, Joshi, & Lave, 1998). Baseline Green, initially developed in 1996 with some funding from the U.S. EPA, specifically targets the construction industry, and is also based on public data sets. Its developers argue that while there can be over 500 upstream impacts from a single building, roughly two dozen impacts account for over 75 percent of total environmental impact. They emphasize that developers should target those particular impacts, and that Baseline Green helps do this (Norris, Fisk III, & McLennan, 2000). The program allows designers or builders to check for impacts at various stages in the design-build process. It groups the hundreds of building components within the familiar Uniformat II construction material specification categories. It runs the program for those inputs, and the results are used to identify which building system categories make the highest contributions to total upstream burden of the project, and which specific inputs within each category rank highest in terms of the environmental improvement leverage they provide.