ABSTRACT
The boundary conditions establish how far back in the materials chain the analysis will go. In most cases the analysis starts with the aquisistion of raw materials and ends with the first manufacturing stage that refines the raw material. There are two kinds of raw materials: primary and secondary. The primary form is raw material that has not been recycled/reused. Secondary raw materials are those that are recycled/reusable materials. Secondary mate rials are given serious consideration beacuse of the following:
• Reduction in use of primary raw materials • Process involved with preparation for use • Emissions and environmental impacts of the processes
After the materials have been refined they are inventory. However, in some life cycle inventories, the inventory is considered raw material because the boundary conditions were set accordingly.
