It is the realm of recycling that exposes the organizational irrationality of the industrial economy like no other. It juxtaposes possibilities for a closed-loop Lake Economy against the existing linear River Economy. But that is only if we can look beyond superficial forms of recycling patched into the accumulationist machine and see the full implications of closed-loop organization based in service. For building materials, this involves a fundamental appreciation of what a building is and how it relates to change. A building is many things and serves many needs, but from a materials perspective, a building is basically a holding device for materials. As noted earlier, compared to most other products, buildings last a long time. We can, therefore, look at the holding patterns created by buildings in two key ways: their durability (how long these patterns and the materials within them last) and their adaptabilityhow easily and ecologically these patterns release old materials and incorporate new ones. These two characteristics roughly correspond to what some analysts (Bringezu, 2002) see as dematerialization (using fewer materials) and rematerialization (using them in more or less closed cycling loops). The problem with existing forms of building within industrial capitalism is that they express precisely the wrong combination of permanence and change. On one hand, not only are buildings and materials are not as durable as they should be; but they are also