As described earlier, a Cradle to Cradle design philosophy is a living systems inspired approach to the design of products and systems. This means it models nature’s processes that allow safe non-toxic chemicals to continually flow in cycles. In this way, any waste from one process becomes food for another process, sometimes literally. For example, the wood produced by trees in nature has many functions in the system, both when alive and after. It provides a solid 3-dimensional structure for animals to live in, birds and squirrels use its twigs to build nests and, as it decays, it is digested by decomposers such as fungi and woodlice and used in respiration for energy. The waste produced by these organisms provides the nutrients for fresh tree growth. It is this cascading and cycling of materials that we need to mimic with our own material use.
This pathway could involve series of new iterations of the constituent materials each providing a fresh use and additional commercial benefit. This type of material cascade can be demonstrated through the timber industry.
Timber is a fabulous construction material. Pound for pound, wood is stronger than steel. Unlike steel, it is also resilient. This combination of strength and resiliency gives wood the ability to absorb the shock of heavy loads. The conversion cost of wood – the cost of manufacturing products from the raw material – is much less than for any other material. In the construction of dwellings, architects consider that wood has more than 10 times the insulating capability of steel or aluminium and is five times more effective as an insulator than concrete or cinder block. Solid wood represents the highest value product in the cascade. Depending on the type of wood used, it can be sold at a premium as high quality furniture. It is valuable because it is strong and can be stained and polished to a high finish. ===Plywood=== Plywood is made from lower grade timber which is cut into thin sheets of wood veneer. Plywood layers (veneers) are glued together with adjacent plies having their grain at right angles to each other for greater strength. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured. Plywood is used instead of plain wood because of its resistance to cracking, shrinkage, and twisting/warping, and its general high degree of strength.
Chipboard (or insulation board) represents the final structural use of wood. It is made by gluing together small fragments of softwood particles with an adhesive under heat and pressure, creating a rigid board with a relatively smooth surface. It is available in a number of densities, normal, medium and high.
Wood pellets are a type of wood fuel, sometimes made from compacted sawdust or other wastes from sawmilling and other wood products manufacture. Pellets are manufactured in several types and grades as fuels for electric power plants, homes, and other applications in between. Pellets are extremely dense and can be produced with a low moisture content (below 10 percent) that allows them to be burned with a very high combustion efficiency.
In order for this cascading of materials to truly mimic nature the process needs to fulfil several other criteria, these include:
Ensure there are defined pathways for the materials as they cascaded. This is important so that loops can be established. This would include returning the ash from burnt wood chips to forests which have been harvested.
Ensure that the use time is defined so that the best performance and value is gained at each stage of the cascade.
Ensure that all chemicals and ingredients used at each stage conform to appropriate guidelines, these include:
- No problematic chemicals in product
- Material Reutilisation score >65 percent
- Plan for product recovery and closing the loop
- Use renewable energy for 50 percent of manufacturing (final assembly)
- Complete an audit to characterise and quantify water use
- Complete an audit of corporate social responsibility practices