So, if office buildings today require 65 percent less steel than 30 years ago, and aluminum cans weigh 30 percent less than 20 years ago, it is as much because of improved profits as it is because of environmental concerns. In fact, these improvements mask a bigger problem. Only 15 percent survived the next 30 years. Reduction of materials, then, not only means lower materials and energy requirements for a product but also extending the useful life of the product. The latter is much harder to achieve than the former.
Some new materials raise very difficult issue.
Steel is fairly easy to recycle and in the United States it is very widely and profitably recycled. Plastic and composites on the other hand, may be very good environmentally in terms of strength, durability, and low energy requirements in manufacturing, but they are almost impossible to recycle. The use of composite materials in cars, for example, which was increasing because of such benefits of corrosion resistance and hence longer useful life, is now likely to be reduced unless ways to reuse or recycleable composites can be found. Recycling and reuse are made easier if the products can be dissembled at the end of their useful life. BMW has not only raised the recycled content of cars to 80 percent, they have a model under development that can be fully disassembled either on return to BMW or at a specialty plant.