M10 AM Building Life-Cycle Capacity in the Greening of Buildings and Construction Consideration
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 341-342

(ABO-1117-185700) The value of recycling to society and its internalization into LCA methodology.

Birat, JP², Yonezawa, K³, Prum, N¹, Guerin, V², Aboussouan, L⁴, ² Arcelor-Research, Metz, France³ Nippon Steel Corporation, Tokyo, Japan¹ Arcelor, Luxembourg, Luxembourg⁴ IISI, Bruxelles, Belgium

ABSTRACT- Recycling is an important activity of developed economies, which creates a dynamic resource of secondary raw materials. Because recycled materials (e.g. steel scrap) are usually chemically close to the material itself, they require less energy and have a lesser impact on the environment than the same materials produced from virgin sources. Recycling, however, is not fully integrated in LCA. There is much freedom left to the LCA practitioner to choose how to take recycling into account, which is somewhat paradoxical as LCA is often used to define policy and therefore ought to be based on a unbiased description of recycling as a practice. This paper proposes a methodology for taking recycling into account within LCA tools with the view of meeting this reality criterion. The proposal is centered on the multiple-recycling model, which best describes the practical way that materials are actually recycled in the economy. The model centers on a set of iron units, which originate from virgin raw material, are then used in the economy and are finally recycled over and over again. Some material is "lost" at each step for recycling, but not for the Life Cycle Inventory, as it goes through its end-of-life whenever it leaves the recycling loop. This is what constitutes the functional unit on which the LCA is carried out. From a practical standpoint, the results obtained for this complex functional unit are attributed to steel on the basis of a specific value (e.g. t of CO₂ per t of steel), which amounts to averaging the impact over the various steps of the recycling process on a weighted average basis, depending on the amount of material recycled at each step.

Key words: sustainability, recycling, methodology, LCA