In this dissertation, regarding the costs and benefits of recycling building materials, the main question was: what are appropriate measures or indices to judge recycle benefits? To answer this question, techniques of emergy analysis were used to evaluate inputs to the production processes of six major building materials and several other secondary materials as well as the inputs to recycle systems for these products in three different recycle trajectories. Emergy is the amount of energy required to make something expressed in units of the same form of energy. The emergy in building materials and recycle systems was expressed as solar energy.; The emergy per mass for building materials vaned from a low of 0.88 E9 sej/g for wood to a high of 1.27 E10 sej/g for aluminum. Generally, emergy per mass is a good indicator of recycle-ability, where materials with high emergy per mass are more recyclable. Recycling added between 1% (concrete) and 568% (wood) to the emergy inputs per gram of building materials. The analysis of materials suggested that recycle of wood may not be advantageous on a large scale, but metals, plastic, and glass have very positive benefits.; Two types of solid waste disposal systems were evaluated: municipal solid wastes (MSW), and construction and demolition (C&D) wastes. Expressed as emergy, the costs of collecting and landfilling (for 50 years) MSW were 264.4 E6 sej/g while sorting recycled materials was evaluated as 8.2 E6 sej/g. The costs of demolition, collection and landfilling C&D wastes were 83.4 E6 sej/g and sorting costs were 6.7 E6 sej/g.; Several different recycle trajectories were identified and analyzed: (1) material recycle, (2) byproduct use, and (3) adaptive reuse. Four recycle indices measuring the benefits of various recycle systems suggested that materials that have large refining costs have greatest potential for high recycle benefits. Aluminum had the highest benefit of about 49.9 where expression as emergy required for emergy cost of recycle. Highest benefits appear to accrue from material recycle systems (ranging from 0.05 to 49.9), followed by adaptive reuse systems (3.3 to 32) and then by byproduct reuse systems (2.4 to 9.2).
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