Biological or Technical Metabolism
A distinction must be made between the biological and technical cycle. The technical cycle comprises all materials and products that consist of raw materials extracted from the earth’s crust, e. g. petroleum-based plastics or metals. These materials or products can – if they have been correctly designed, constructed or manufactured – be re-used after a cycle has ended, or sorted by type and recycled. They thus become a valuable resource for new products. The biological cycle comprises all materials or products produced by photosynthesis and represents a much larger metabolism. While the plastic polyethylene, for example, must always be reused as such in the same cycle, an untreated wooden beam can decompose in the biological cycle and provide nutrients for a mushroom insulation.