cultural dimensions of a healthy built environment. As the environmental movement has increasingly touted the importance of reduction and reuse over recycling, so also the green building movement has come to reaffirm A.N. Didrons (1839) famous maxim, It is better to preserve than to repair, better to repair than to restore, better to restore than to reconstruct. Building preservation is, of course, only one component in a strategy to conserve materials, and it does not directly deal with many of the unhealthy impacts of money and markets on building life listed above. Some initiatives to rectify some these imbalances will be discussed in Chapters VI (on consumption) and VII (on regulation). But it is important here to recognize that awareness is gradually growing within the green building movement of the importance of preserving, maintaining, and refining existing buildings as an essential dimension of resource conservation. For the newly emerging field of construction ecology this awareness is part of a more comprehensive understanding of how buildings change, and thus how buildings might be designed to facilitate positive change with minimal resource input. Theoretically, the most important breakthrough has been the concept of shearing layerswhich I will consider before moving on to the recycling and reuse of individual materials.