The material flows found on earth can be divided into two categories:
Biomass and industrial mass. From our perspective, the two constitute flows of biological and technological nutrients. Intelligent production means that all materials are able to flow within a metabolism, be that a biological or technological one. In a biological metabolism, lots of materials are broken down by micro-organisms to form new nutrients. Biodegradable products are used as compost which is then used to form a nutrient basis for new natural resources.
All products that are circulating as part of this metabolism are termed consumption products. Certain packaging materials, clothing and parts that wear and tear such as car tyres and brake discs were designed for such a cycle.
A technological metabolism consists of artificially-created and actively-managed material flows. The idea is that industrial mass is allowed to circulate in closed systems whilst maintaining a constant quality level. The fact that the system is a closed one is a prerequisite for the possible use of toxic substances. These substances have proven to be essential in the manufacture of certain products such as insulated windows. The ease of disassembly and the careful choice of materials for a product is a fundamental aspect of the design.
Products and materials in this cycle are called products for service. The name is derived from the concept of a service product. Washing machines, for example, are no longer bought rather their service is used at a charge. As such, this leasing principle means that the material remains in the ownership of the manufacturer and is returned to them after a certain defined period of usage. One advantage of this system is that the manufacturer can use materials of a higher standard and quality.