TRACKING THE LIFE CYCLE OF CONSTRUCTION STEEL: THE DEVELOPMENT OF A RESOURCE LOOP

Abstract

Cradle-to-grave model is established on the assumption of a model of one-way, linear flow of materials in the industrial system. Eco-efficiency, as the design strategy of the cradle-to-grave model, aims to reduce the reliance of industry on resources while decreasing the negative consequences to the environment; but designers do not consider the usefulness of a material after it ends its life cycle. Eco-effectiveness and cradle-to-cradle design present a new concept as an alternative design strategy by modeling material-flow based on biological metabolism processes. This concept assumes that a material will have to be rejuvenated at the end of its functional life, and reused for another use. Both of those models: cradle-to-cradle and cradle-to-grave, integrate energy and materials in different processes, such as extract, manufacture, transport, install, deconstruct, demolish and dispose of materials. This thesis developed a "resource loop" which represents both the cradle-to-cradle and cradle-to-grave model to accounting materials and energy. Construction steel is chosen as a case study to show the developing processes, and identify "feeds" and "leaks" within the resource loop. The thesis found: 1) The transportation process generates a significant amount of leaks; 2) Materials and energy accounting methods are not comprehensive enough; 3) The resource loop needs to be improved to implement the cradle-to-cradle model in construction industry. In the end of this thesis, some suggestions will be given for future research in implementing the cradle-to-cradle design.