For materials, Bradley Guy (2002) emphasizes a threefold design strategy: design for reuse, design for remanufacturing, and design for recyclingwith reuse requiring the least processing and recycling the most. The priority would be to minimize the need for reprocessing, and very generally, the aim would be to incorporate three basic principles (Berge, 2000, p. 11-15): 1. Separate layers, according to the understanding of shearing layers. 2. Possibilities for disassembly within each layer: sections that tend to wear quicker can be more reinforced or more easily replaced. 3. Use of standardized monomaterial components: including primary monomaterials like untreated wood and secondary monomaterials like concrete, glass or cellulose fibre. Components made of different materials laminated together arent so appropriate since their various elements tend to decay at different rates, they are difficult or impossible to separate, and they make for inferior quality if recycled while blended. Nevertheless, there are many dynamics to consider in proper design. Materials and components can be clustered in a number of ways. And much of the disassembly can and should take place away from the building site. The larger clusters should be dismantled on the building site, but many assemblies and specific materials can be separated offsite in places like factories and resource recovery parks. Guy and Shell (2002) highlight other questions relevant to how a building should be designed to be assembled and disassembled: What parts of the building support other parts? What parts of the building are self-supporting ? Where do specialized service inputs and outputs (telecommunications, electricity, water, gas, wastewater, supply and exhaust air) occur and how are these flow mechanisms constructed ? What parts of the building are subject to the most stresses from climate? What parts of the building are most subject to wear from human use and change from aesthetic preference? What parts of the building are most subject to alteration based upon functional, economic, life-expectancy, or technological requirements? What parts of the building are comprised of components and sub-components based upon a complex set of functional requirements and what parts serve only one function and hence are comprised of relatively homogenous materials?